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WHO-ROHC SPONSORED
TRAINING PROGRAMME
ON
OCCUPATIONAL HEALTH
IN AGRICULTURAL SECTOR
8th TO 12th FEBRUARY 1999
VENUE
REGIONAL OCCUPATIONAL HEALTH CENTRE (SOUTHERN)
INDIAN COUNCIL OF MEDICAL RESEARCH
LIBRARY AND INFORMATION CENTRE
BANGALORE MEDICAL COLLEGE CAMPUS
BANGALORE
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REGIONAL OCCUPATIONAL HEALTH CENTRE (SOUTHERN)
INDIAN COUNCIL OF MEDICAL RESEARCH
WHO-ROHC SPONSORED TRAINING PROGRAMME ON
OCCUPATIONAL HEALTH IN AGRICULTURAL SECTOR
8™ TO 12™ FEBRUARY 1999
PROGRAMME
DAY -1 :
8™ FEBRUARY 1999 (MONDAY)
9.00 Hrs.
10.00 Hrs.
11.00 Hrs.
REGISTRATION
INAUGURATION
TEA
TIME
11.30 Hrs.
________________ LECTURE_________________
Occupational Health Problems of Agricultural Workers
in India-An Overview___________________________
Clinical Approach to Occupational Asthma_________
LUNCH______________________________________
Occupational Health Aspects In Sericulture_________
Field Trip To Sericulture Farm,
Talaghattapura, Bangalore
12.15 Hrs.
13.00 Hrs.
14.00 Hrs.
14.45 -17.30
Hrs.
DAY -2 :
TIME
9.30 Hrs.
10.15 Hrs.
11.00 Hrs.
11.30 Hrs.
12.15 Hrs.
13.00 Hrs.
14.00-17.00
Hrs
13.00 Hrs.
14.00 Hrs.
14.45 Hrs.
15.30 Hrs.
16.00 Hrs.
DR. A. OMPRAKASH
DR. S.B. DANDIN
9™ FEBRUARY 1999 (TUESDAY)
_______ FACULTY
r____________ LECTURE_______________
DR. H.N. SAIYED
Silicosis and Silico-Tuberculosis In Rural Industry^/
DR. D.P. NAG
Toxic Lung Injury___________________________
TEA_____________________________________
DR (MRS.) P. JAGOTA
Tuberculosis Among Agricultural Workers________
DR. P. K. NAG
Ergonomic Practices In Agricultural Processes
LUNCH___________________________________
Field Trip To M/s. Mysore Agro Feeds &
M/s. Gayathri Flour Mills, Bangalore
DAY -3 :
TIME
9.30 Hrs.
10.15 Hrs.
11.00 Hrs.
11.30 Hrs.
12.15 Hrs.
_______ FACULTY
DR. H. N. SAIYED
10th FEBRUARY 1999 (WEDNESDAY)
__________________ LECTURE__________________
Pesticide Residues In Food Chain And Their Impact
Pesticide Related Health Problems v______________
TEA
______________________________
Pesticides And Human Health___________________
Cancer Scenario in rural India With A Brief Review of
Cancers In Farm And Agricultural Workers _______
LUNCH______________________________________
Challenges Of Agricultural Medicine For PHC Doctors
Change In Trends In Alcoholism__________________
TEA________________________________________
Care Of Surgical Wound In Industrial Set-up
_______ FACULTY________
DR, M.D. AWASTHI
DR.(MRS.)S. KULSRESTHA
DR . D.P. NAG______
DR. A. NANDAKUMAR
DR. RAVINARAYAN
DR. G.S. PALAKSHA
DR. FRED SIMON OOMON
P.T.O
:: 2 ::
DAY-4 :
11th FEBRUARY 1999 (THURSDAY)
I
TIME
! 9.30 Hrs.
10.15 Hrs.
LECTURE
Veterinary Zoonosis____________________________
Occupational Health Problems Among Poultry Workers
11.00 Hrs.
- 11.30 Hrs.
12.15 Hrs.
13.00 Hrs.
TEA______________________________________
Occupational Health Hazards Among Dairy Workers_____ ________________
DR. M.N. KAILASH
Health Hazards Among Small Laboratory Animal Workers DR. B.R. SRINATH
LUNCH________ __________________________________________________
Field Trip To Bangalore Dairy
14.00-17.00
FACULTY
DR. R. RAGHAVAN
DR.R.N.SRINIVASA
GOWDA
i Hrs
DAY-5 :
TIME
; 9.30 Hrs.
! 10.15 Hrs.
| 11.00 Hrs.
11.30 Hrs.
12.15 Hrs.
13.00 Hrs.
14.00-16.00
Hrs
12th FEBRUARY 1999 (FRIDAY)
___________________ LECTURE___________________
Causation of Work Environment And Chemically Induced
Cardiac Diseases________________________________
Overview of Occupational Health And Safety___________
TEA___________________________________________
Industrial Hygiene Survey In Coir, Agarbathi And Tea
Industry
_____________________________________
Health Hazards Of Workers Engaged In Coir, Agrabathi
And Tea Industry J_______________________________
LUNCH_________________________________________
Evaluation Of The Programme And Recommendations
FACULTY
DR. U.B. KHANOLKAR
DR. RADHAKRISHNA
DR. V.KRISHNA
MURTHY__________
DR. H.R. RAJMOHAN
REGIONAL OCCUPATIONAL HEALTH CENTRE (SOUTHERN)
INDIAN COUNCIL OF MEDICAL RESEARCH
WHO-ROHC SPONSORED TRAINING PROGRAMME ON
OCCUPATIONAL HEALTH IN AGRICULTURAL SECTOR
8th TO 12th FEBRUARY 1999
LIST OF PARTICIPANTS
ANDHRA PRADESH
KERALA
1.
DR. N. LAXMAN RAO
Adakal SHC
Mahaboobnagar Dist.
Andhra Pradesh
9.
DR. AYSHA BEGUM
Asst. Surgeon
PHC Puthenthoppu
Thiruvananthapuram, Kerala
2.
DR. S. VIJAYAKUMAR
Uppair PHC
Mahaboobnagar
Andhra Pradesh
10.
DR. K.P. CLEETUS
Civil Surgeon
C.H. Centre, Vellanad
Thiruvananthapruam , Kerala
3.
DR. K.R. NAGARAJA RAO
B. Kothakota
Chittoor Dist.
Andhra Pradesh
11.
DR. M. ABDUL RASHEED
Civil Surgeon
C.H. Centre, Kanyakulangara
Thiruvananthapuram, Kerala
4.
DR. D.V. SUBBA RAYUDU
Garnamitla
Chittoor dist.
Andhra Pradesh
KARNATAKA
5.
6.
12.
DR. SHIVANANJUNDAIAH
PHC, Krishnarajapuram
Bangalore (U) Dist.
Karnataka
13.
DR. ESHWARAPRASAD
PHC, Jigani, Anekal Taluk
Bangalore (U) Dist.
Karnataka
14.
DR. J. SHANKAR
PHC, Singasandra
Bangalore (U) Dist.
Karnataka
DR. PRADEEP PADWAL
Health Officer
PHC, Bichelim
Goa
15.
DR. H. SHIVAKUMAR
PHC, Kengeri
Bangalore (U) Dist.
Karnataka
DR. V.B. DEVARI
Health Officer
PHC, Curtorim
Goa
16.
DR. K.S. VEDARAJ
PHC, Bidadi
Bangalore (U) Dist.
Karnataka
DR. T. SATYANARAYANA
PHC, Karapa
East Godavari dist.
Andhra Pradesh
DR. K. SESHAGIRI RAO
PHC, Venapalli
East Godavari Dist.
Andhra Pradesh
GOA
8.
17.
DR. DEVATAPPA SALOTAGI
PHC, Jevargi
Gulbarga Dist.
Karnataka
TAMIL NADU
18.
DR. T. PARTHASARATHY
Medical Officer, PHC
Silamarathupatty, Periyakulam,
Theni Dist., Tamil Nadu
19.
DR. V. KALAVATHY
Medical Officer, PHC
Periyakulam, Theni Dist.,
Tamil Nadu
20.
DR. SENTHIL
Medical Officer, PHC
Chekkanoorani, Madurai
Tamil Nadu
21.
DR. ELANGOVAN
PHC Kabisthalam
Thanjavur
Tamil Nadu
22.
DR. SAKTHIVEL
Medical Officer
PHC, Paralachi, Virudhunagar
Tamil Nadu
23.
DR. RAM MOHAN
PHC, Puduvalasai
Ramanathapuram Dist.
Tamil Nadu
PONDICHERRY
24.
DR. S. MOHAN KUMAR
Medial Officer, PHC
Ambakaratur, Karaikal
Pondicherry
REGIONAL OCCUPATIONAL HEALTH CENTRE (SOUTHERN)
INDIAN COUNCIL OF MEDICAL RESEARCH
WHO-ROHC SPONSORED TRAINING PROGRAMME ON
OCCUPATIONAL HEALTH PROBLEMS IN AGRICULTURAL SECTOR
8th TO 12™ FEBRUARY 1999
LIST OF RESOURCE PERSONS
1.
I
DR. H.N. SAIYED
Director
National Institute of Occupational
Health
Meghani Nagar
Ahmedabad - 380 016.
7.
2.
DR. A. OMPRAKASH
5/A, Kumarakrupa Road
High Grounds
Bangalore - 560 001.
8.
DR.(MRS.) SANDHYA KULSRESTHA
Medical Toxicologist
Directorate of Plant Protection
Quarantine & Storage
N.H. IV, Faridabad-121 001.
3.
DR. S.B.DANDIN
Director,
Karnataka State Sericulture Research
and Development Institute,
Thalaghattapura,
Bangalore -560 062.
9.
DR.A.NANDAKUMAR
Project Officer
National Cancer Registry Programme
Kidwai Memorial Institute of Oncology
Bangalore - 560 029.
4.
DR.D.P.NAG
Officer-In-charge
Regional Occupational Health Centre
Library Information Centre Block
Bangalore Medical College Campus
Bangalore - 560 002.
10.
DR. RAVINARAYAN
Community Health Centre, No.367,
Srinivasa Nilaya, Jakkasandra,
r Main Road, First Block,
Koramangala, Bangalore - 560 034.
5.
DR. (MRS.) P.JAGOTA
Director
National Tuberculosis Institute
No. 8, ‘Avalon’, Bellary Road
Bangalore - 560 001.
11.
DR.G.S. PALAKSHA
Chief Medical Superintendent
Psychiatrist,
H.A.L. Hospital
DR.P.K.NAG
Deputy Director
National Institute of Occupational
Health, Meghani Nagar
Ahmedabad - 380 016.
12.
6.
DR. M.D. AWASTHI
Principal Scientist
Division of Soil Sciences
Indian Institute of Horticultural
Research, Hesarghatta
Bangalore - 569 089.
Bangalore - 560 017.
DR. FRED SIMON OOMON
Dy. Chief of Medical Services
H.A.L. Hospital
Bangalore - 560 017.
13.
DR. R. RAGHAVAN
Professor & Head
Dept, of Veterinary Microbiology
Veterinary College, University of
Agricultural Sciences, Hebbal,
Bangalore - 560 024.
14.
DR. R.N.SRINIVASA GOWDA
Director
Institute of Animal Health &
Veterinary Biologicals
Hebbal
Bangalore - 560 024.
15.
DR. M.N. KAILASH
Professor & Head
Dept, of Dairy Production
Veterinary College
University of Agricultural Sciences
Bangalore - 560 012.
16.
DR.B.R.SRINATH
Principal Research Scientist
Central Animal Facility
Indian Institute of Science
Bangalore - 560 012.
17.
DR. U.B. KHANOLKAR
Cardiologist
Wockhardt Hospital and
Heart Institute
14, Cunningham road
Bangalore - 560 016.
18.
DR. RADHAKR1SHNA
Chief Medical Officer
I.T.I. General Hospital
Dooravani Nagar
Bangalore-560 016.
19.
DR.V.KRISHNA MURTHY
Senior Research Officer
Regional Occupational Health Centre
Library and Information Centre
Bangalore Medical College Campus
Bangalore - 560 012.
20.
DR. H.R.RAJMOHAN
Assist Director
Regional Occupational Health Centre
Library and Information Centre
Bangalore Medical College Campus
Bangalore - 560 012.
LIST OF LECTURES
1.
Occupational Health Problems Of Agricultural Workers
In India - An Overview : DR. H.N. SAIYED
2.
Clinical Approach To Occupational Asthma : DR. A. OMPRAKASH
3.
Occupational Health Aspects In Sericulture : DR. S.B. DANDIN
4.
Silicosis And Silico-Tuberculosis In Rural Industry: DR. H.N. SAIYED
5.
Toxic Lung Injury : DR. D.P. NAG
6.
Tuberculosis Among Agricultural Workers : DR. (MRS.) P. JAGOTA
7.
Ergonomic Practices In Agricultural Processes : DR. P.K. NAG
8.
Pesticide Residues In Food Chain And Their Impact: DR. M.D. AWASTHI
9.
Pesticide Related Health Problems : DR. (MRS.) S. KULSRESTHA
10.
Pesticides And Human Health : DR. D.P. NAG
11.
Cancer Scenario In Rural India With A Brief Review Of Cancers In
Farm And Agricultural Workers : DR.A. NANDAKUMAR
12.
Challenges Of Agricultural Medicine For PHC Doctors : DR. RAVINARAYAN
13.
Change In Trends In Alcoholism : DR. G.S. PALAKSHA
14.
Care Of Surgical Wound In Industrial Set Up : DR. FRED SIMON OOMON
15.
Veterinary Zoonosis : DR. R. RAGHAVAN
16.
Occupational Health Problems Among Poultry Workers :
DR. R.N. SRINIVASA GOWDA
17.
Occupational Health Hazards Among Dairy Workers : DR. M.N. KAILASH
18.
Health Hazards Among Small Laboratory Animal Workers: DR. B.R. SRINATH
19.
Causation Of Work Environment And Chemically Induced
Cardiac Diseases : DR. U.B. KHANOLKAR
20.
Overview Of Occupational Health And Safety : DR. RADHAKRISHNA
21.
Industrial Hygiene Survey In Coir, Agarbathi And
Tea Industry : DR. V. KRISHNA MURTHY
22.
Health Hazards Of Workers Engaged In Coir,
Agartoathi And Tea Industry : DR. H.R. RAJMOHAN
ROHG-WHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999: L.N.-1
Occupational Health Problems of Agricultural Workers in India
- An Overview
DR. H. N.SAIYED
Director, National Institute of Occupational Health, Meghani Nagar, Ahmedabad380 016, Gujarat.
Contribution of Agriculture to Indian Economy
The Green Revolution has changed the face of Indian agriculture since
Independence. Food grain production, which stood at a mere 50 million tonnes
at Independence, has increased nearly four times by the end of 1996-97 crop
year. Latest estimates for 1996-97 put the total food grain production at an all
time high of 198.17 million tonnes.
Post Independence farming has been marked by crop diversification. New
crops like soyabean and sunflower are being adopted increasingly by farmers. As
a result of intensive dissemination of information on new methods of farming,
farmers are now using more inputs and technology resulting in diversification of
and an increase in cropping intensity. Today many crops are planted and cereals
are grown in rotation with horticulture instead of a single crop annually.
Employment in Agriculture Sector
Agriculture sector remains primary source of employment in India. As per
1991 Census1, the working population of India was 278.9 million (34.17%) out of
total population of 816 million. Out of this 278.9 million workers, 186.2 million
(66.7%) were engaged in various agriculture related operations such as farming,
live stock, forestry, fishing, hunting etc (Table 1). The proportion of individuals
engaged in agricultural operations is much higher in India than that in the
industrialized nations. For example, in U.S.A, only about 2% of the total
population is engaged in agriculture related operations and in most of West
European countries it is less than 10%. Further analysis of 1991 Census data
reveals that amongst farmers (180.9 million or 64.9% of the total working
population), about 131 million were men and about 50 million were women. It
may be noted with concern that 34.7% men and 56.8% women farmers were
working as agricultural labourer (Table-2). According to Census, an “agriculture
labourer'’ is a person who works on another person’s land for wages in money or
kind or share. He (or she) does not have right of lease or contract on land on
which he (or she) works.
Year wise analysis of employment in agriculture sector indicate that the
number of people engaged in agriculture operations (excluding those engaged in
live stock, forestry, fishing, hunting etc) has increased from 125 million in 1971 to
2
Occupational Health Problems of Agricultural Workers in India - An Overview
about 180.9 million in 1991. However, the percentage of total employment in
agriculture sector amongst men has decreased from 67.5% in 1971 to 60.7% in
1991 (Table-3). In women workers this figure has changed very little and has
remained around 80%. In other words, amongst women folk there are not much
change in the pattern of employment.
Table 1 : Distribution of working and non-working population by Industry
division. (Census, 1991)
Men
Women
No.
No.
%
Cultivation_______________ 85.6 39.63 21.5
Agricultural labour________ 45.5 21.06 28.3
Live stock, forestry, fishing 4.3
1.99
1.0
135.4
Agricultural operations_____
62.69 50.8
0.2
Non agricultural operations
1.5
0.69
Total
main
working 216 100.0
62.9
Total population
423.6 100 392.6
Total
%
No.
%
34.18
44.99
1.59
80.76
0.32
107.1
73.8
5.3
186.2
1.7
38.40
26.46
1.90
66.76
0.61
100.00
100
100.001 278.9
100 | 816.2
Table 2 : Distribution of cultivators versus agricultural labourers
Men
Women
Total
85.6 (65.29) 21.5 (43.17) 107.1(59.20)
Cultivators
Agriculture labourerl 45.5 (34.70) 28.3 (56.82) 73.8(40.79)
49.8
Total farmers
131.1
180.9
Table 3 : Sex wise employment in agriculture (farming only) and non
agriculture sector in India (in million)
Year
1971
1981
1991
________ Women
__________ Men
NonAgricultural
NonAgricultural
6.24(19.91)
25.10
100.66(67.49) 48.49 (32.51)
9.28 (20,62)
35.70
112.33
65.22 (36.63)
13.12 (20.85)
49.80
131.09
84,93 (39.31)
Major Occupational Health Problems of Agricultural Workers
The Indian farmers, like those of other third world countries, have many
social and health problems. The housing and sanitation are generally very poor
and predisposes to infectious diseases such as malaria, filaria, diarrheal
diseases, typhoid, worm infestations, hepatitis etc. The poor economic conditions
lead to the problem of malnutrition. This results in a vicious circle of lower output,
decreased income, poor socio-economic status, poor health and so on. Studies
I
3
Occupational Health Probiems of Agricultural Workers in India - An Overview
in India2 have shown that if a person with inadequate diet is given 20 percent
increase in the calories it results in 50 percent increased work capacity and
output.
Over the past three decades there have been remarkable changes in the
agriculture practices. Mechanization of various agriculture operations has been
introduced. There is increasing use of chemicals such as chemical fertilizers and
pesticides. These modified agriculture practices have introduced newer
occupational health problems. The major occupational health problems of
farmers are pesticide exposure, accidents and ergonomic problems, exposure to
various biological agents, extreme climatic conditions etc. Creation of industrial
estates near the agriculture land has lead to problems due to industrial effluents
to neighbourhood farmers.
In following paragraphs some of the occupational health problems of
Indian farmers along with studies carried out by National Institute of Occupational
Health (NIOH) have been discussed.
Pesticide Exposure Related Problems
Following tragic famine of Bengal in 1941-42, the Government of India
appointed a commission called, Indian Famine Enquiry Commission to
investigate the causes of famine and suggest suitable action. The Commission
concluded, “If full benefits of irrigation, manuring and improved varieties are to be
assured, effective action must be taken to deal with the diseases, pests, worms
and weeds, crop protection is an important factor in increasing production.”3
DDT and BHC were introduced in India, in 1948-49 for public health and
agricultural use. Since then, some new pesticides are introduced every year and
today there are 143 pesticides registered for use in the country under section
9(3) of the Insecticide Act, 1968. The consumption of technical grade pesticides
today in India is about 81,000 MT of which about 80% is used in agriculture and
remaining 20% is used for public health purpose and the use would increase to
1,18,000 MT per annum by 2,000 A.D.4 The turn over of pesticide business in
India in 1993-94,1994-95 and 1995-96 was 18,750, 22,500 and 27,000 million
rupees respectively.
Injudicious and indiscriminate use of chemical pesticides has resulted in
•
Health hazards to human beings from direct or indirect exposure to
pesticides.
•
Development of resistance in pests to pesticides leading to a vicious cycle of
use of greater dose leading emergence of new resistant species and pest
resurgence due to destruction of natural enemies.
4
Occupational Health Problems of Agricultural Workers in India - An Overview
•
Pesticide residues in food, water, soil and fodder.
•
Poisoning of wildlife and livestock.
•
Environmental pollution.
•
Ecological imbalance.
Health Hazards to Human beings from Direct or Indirect Exposure to
Pesticides.
The basic metabolic processes at cellular or sub-cellular level is similar in
all living organisms and therefore adverse effects of the chemical pesticides are
always expected in non-target organisms including human-beings. Persons most
likely to be affected are those with direct contact i.e. people who are involved in
manufacture, formulation and use or application of pesticides. Use of pesticides
at any stage of food production can lead to exposure of general population. The
problem would naturally be more serious with pesticides like organochlorine
compounds, which are persistent in nature and capable of undergoing bio
magnification. NIOH has carried out studies related to acute health effects
resulting from exposure to pesticides following its spray. Some of these studies
have been described below.
•
Effects of ultra low volume (ULV) aerial spray of phosphomidon (OP
insecticide) on human volunteers : A field study5
Toxicological effects of ultra low volume aerial spray of phosphamidon, a
highly toxic organophosphorus insecticide, were evaluated in volunteers. A
single ULV aerial application of phosphamidon in doses of 550 g/ha produced
irritation of eyes and conjunctiva in majority of exposed persons at the time of
insecticide application. Plasma cholinesterase activity was 75% of the pre
exposure value on the third day following exposure. No significant reduction
in RBC cholinesterase activity was observed. On the basis of observation it
was recommended that the aerial spray should not be repeated in the same
area within few weeks period to avoid cumulative effects among exposed
subjects.
•
Cardiac toxicity following short-term exposure to methomyl in spraymen
and rabbits0
Methomyl, a carbamate insecticide, is used as an insecticide since 1966 in
USA, particularly for the control of lepidopterous insects in crops including
fruits, vines, hops, vegetables, grains, soya beans, cotton, sweet com and
ornamentals. Its indoor uses include the control of flies in animal houses and
dairies. It was introduced in India for the control of bollworm in cotton in
5
Occupabcxiai Health Problems of Agricultural Workers in Incia - An Overview
Andhra Pradesh. Soon after its introduction, there were news about alleged
deaths and toxicity amongst the applicators. To investigate the toxicity of
methomyl, a short-term study was carried out by National Institute of
Occupational Health at the request of the Ministry of Agriculture, Government
of India. The study consisted of two components, (a). Human study and (b).
Experimental study in rabbits.
•
Human study
The study group comprised of 22 healthy male agriculture workers, aged
between 18 and 42 years, who had not sprayed any kind of pesticides at
least one month before the beginning of the study. The guidelines laid
down by the ethical committee of the institute for medical studies involving
human exposure was strictly followed. These subjects sprayed methomyl
in a large cotton farm for 5 days using prescribed concentration. The
spraying schedule was carried out under medical supervision. The
spraymen were neither allowed to smoke or to eat during 4 hours of
spray. They used protective gloves, overall, goggles and mask.
All the study subjects underwent thorough medical examination including
electrocardiography (ECG), estimation of cholinesterase (ChE), serum
glutamic oxalo-acetic transaminase (SGOT) and lactate dehydrogenase
(LDH) before exposure, at the end of the 5 days exposure and one-week
after cessation of exposure. Significant changes were observed in ECG
and levels of ChE and LDH. Major ECG abnormality was changes in the T
wave observed in 10 (45.4%) subjects. These changes included
diminution in height of T wave, T wave inversion and significant left ward
deviation of its frontal plane axis. These changes correlated with post
exposure rise in LDH levels indicating possible cardio-toxic effect of
methomyl.
•
Study in rabbits
As the above-mentioned ECG findings were reported for the first time,
it was necessary to verify these findings through experimental studies.
A pilot experimental study was performed in four rabbits. Methomyl
was given at dose of 4 mg Kg -1 body weight on first day and 5 mg Kg ”
1 body weight on second day. Three out of four rabbits showed the
same ECG changes as observed in spraymen. The depth of T wave
inversion increased on the next day following higher dosages. These
findings confirmed the cardiac toxicity of methomyl observed in
spraymen.
6
Occupational Health Problems of Agricultural Workers in India - An Overview
Our recent study in workers engaged in formulation of methomyl,
showed a significant rise in the levels of lactate dehydrogenase
(LDH), alpha hydroxybutarate dehydrogenase (HBDH), and glutamate
pyruvate transaminase (GPT) enzymes after a week’s exposure. Rise
in these enzymes indicates possible cardio-toxic effects of methomyl
in these workers.
Comprehensive data on long term effects such as teratogenic, mutagenic
and carcinogenic potentialities of these chemicals are usually not available. Even
short-term unusual effects may be discovered long time after its introduction.
Many of these pesticides enter into the food chain and may even undergo bio
magnification thus affecting the consumers, which includes the more vulnerable
group such as children, pregnant women and old and sick persons.
Recently there has been greater concern over the endocrine disrupting
effects of many persistent pesticides belonging mainly to organochlorine group of
insecticides has been expressed. More and more direct evidence is accumulating
indicating endocrine effects of pesticides on aquatic animal and plant life, birds
and reptiles. There are indications of possibility of such effects on human beings.
Ergonomic Problems of Farmers
Large numbers of Indian farmers continue to use traditional tools such as
hoes, sickles, manual weeders etc. These tools are designed by the local
artisans. There is great scope for improving design of these basic tools to make
them more efficient and safe. NIOH scientists have carried out some research
projects related to this aspect some of them have been summarized below.
Ergonomics in the hoeing operation7
Hoe is a basic tool in agriculture, civil construction and forestry. A study was
undertaken by the NIOH scientists, in seven male farmers using two types of
hoes (A & B), to evaluate physiological and biomechanical strains in using
different sizes of hoes and to optimize hoeing tasks in different models. The
heart rates (161 - 176 beats/min.) and VO2 demands (71 - 89% VO2max)
indicated extremely heavy work loads. Hoe A (blade handle angle = 65°) was
less strenuous in low lift (LL), while hoe B (blade handle angle = 87° ) was
better in high lift (HL) work. During hoeing sequence, the torque and
compressive forces at the L5 - S1 increased with trunk inclination upto 65°;
beyond 55° inclination, the torque at the L5 - 81 exceeded the upper limit 155
nM allowed for a day’s work. The work output was optimized equating at 50%
VO2 rnax. i.e. stroke rate 53 and 21 strokes/min., weight of soil dug = 123 and
54 kg/min. and area of soil dug =1.34 and 0.33 Sq. M/min. in LL and HL work
respectively. In general farmers are suggested to adopt the LL mode of
hoeing; with a ten-minute work to seven-min. rest ratio.
7
Occupational Health Probtems of Agricultural Workers in India - An Overview
•
Ergonomics in sickle operation*
In India, although mechanization of harvesting operation has been introduced
in some parts of the country, the use of sickle still continue. It has been
realized that ergonomics has immense potential in achieving better
performance in farm task. There is lack of qualitative and quantitative
information on the application of ergonomics to the evaluation of relative
performance of different sickles on some common crops. A study was
designed to compare different models of sickles traditionally used and to
specify the design characteristics of a sickle, which have influence on human
comfort, efficiency and safety. Sickle operation in harvesting was analysed
with reference to design features of nine different types of sickles, and field
and laboratory based investigations on biomechanical stresses and
physiological valuation on six farmers. The study results indicated that the
blade geometry contributes significantly to human performances and there is
ample scope for further design optimization. The suggested modifications
were (1) sickle weight - 200 g; (2) total length of sickle - 33 cm; (3) handle
length - 11 cm.; (4) handle diameter - 3 cm.; (5) radius of blade curvature 15cm .; (6) blade concavity - 5 cm; (7) in case of serrated sickle, tooth pitch 0.20 cm and tooth angle 60°; (8) ratio of cutting surface to cord length -1.20.
Occupatjonal Health Problems of Agricultural Workers in Incfca - An Overview
•
Physiological reactions of women workers engaged in Indian agricultural
work*
Physiological measurements in women agricultural labourers have four
practical applications :
•
To provide a basis for nutritional counseling of the individual worker for
the purpose of metabolic balance and growth maintenance during normal
life, pregnancy and lactation.
•
To judge the suitability of tasks for the individual worker and to match the
worker to the job and vice versa.
•
Where appropriate to encourage some form of restful rather than active
recreation in order to reduce taxing of the body and
•
To develop guidelines for tasks involved agricultural work over the total
work shift in different environmental conditions for providing better
working conditions so as to minimize the possible fatigue of workers.
The physiological reactions of eight women workers in agricultural
tasks and leisure time activities were determined with a view to standardize
occupational workload. A majority of the tasks performed by the workers were
8
Occupational Health Problems of Agricultural Workers in Inda - An Overview
within 33% of VO2
but some of the jobs classified as moderate and heavy
required 39% to 55% of VO2
None of the agricultural task could be
considered extremely heavy. The whole day energy expenditure of these
workers was estimated to be 1061 MJ or 450 KJ less than their total energy
intake. About 52% of this energy were required for the day’s work and
remainder was expended for the maintenance of postures and other
activities. On the basis of the study it was suggested that the workers may be
allowed to work up to the limit of 40% VO.*2 max f°r longer duration, if an
increase in productivity was desired.
•
Effectiveness of some simple agricultural weeders with reference to
physiological responses
Seven different types of weeders, namely (1) double sweep-type (2)
projection finger- type (3) single raw multiple sweep-type (4) blade and rack
type (5) wheel and hoe-type (6) single sweep wheel-type and (7) triple sweep
wheel-type were studied with reference to physiological responses and are
weeded per unit time by using each method, and manual weeding. Five
young skilled agricultural workers were used for the study. Average work
pulse rate varied from 105 to 120 beats/min. in weeding operations using
blade and rack-type, projection finger-type and double sweep-type weeders.
The lowest cardiac response was observed with wheel and hoe-type weeder.
Blood pressure responses were also higher with other three weeders
mentioned above. Pulmonary demand was around 27 L/min. with all the
weeders; but the highest oxygen uptake (56% of the maximal oxygen uptake)
occurred in case of a projection finger-type weeder. The maximum area was
weeded (1.42 sq./min.) by the wheel and hoe- type weeder. Comparing
physiological demand, preference of workers and work performance, the
wheel and hoe-type of weeder was found to be best suited for Indian
conditions.
Studies on Occupational Health Problems in Agricultural Tobacco Workers
India is the third largest tobacco growing country in the world producing
about 8% of the total world tobacco production. There are about 7 lakh workers
engaged in growing of tobacco and about 5 lakh workers engaged in curing of it.
Andhra Pradesh and Gujarat are two major tobacco-growing states in the country
responsible for about 80% of the tobacco grown in the country. Weizencker and
Deal11 described the first report on the symptom complex known as “green
tobacco sickness”. The “green tobacco sickness” consists of headache, nausea,
vomiting, giddiness, weakness and fatigue and fluctuation in blood pressure and
heart rate. The condition is self limiting and lasts for few hours. It believed to be
caused by absorption of nicotine through skin. The presence of “green tobacco
sickness” in the Indian tobacco cultivators was described by NIOH scientists1 in
9
Occupational Health Probtems of Agricuttural Workers in Irxia - An Overview
non-Virginia tobacco growers of Gujarat. Subsequently the same condition was
described in the Virginia tobacco growers of Andhra Pradesh13. It was
demonstrated in both the studies that there was significant absorption of nicotine
as evidenced from high levels of nicotine and its major metabolite, cotinine in the
urine.
To prevent absorption of nicotine and subsequent occurrence of “green
tobacco symptoms, NIOH scientists made trial with cotton and rubber gloves in
100 tobacco cultivators who reported to suffer from “green tobacco sickness”. It
was found that the use of rubber gloves offered protection and the alleviation of
symptoms was reported by about 93% of the subjects. There was also significant
reduction in excretion of nicotine and cotinine in urine14. However, the gloves
could not be made popular because they were found to be expensive and could
not be re-used after washing. At present NIOH scientists are making trial with
disposable polyethylene rubber gloves which are very cheap, affordable and
effective.
Summary and Conclusions
Agriculture industry continues to be the principal source of employment in
India. Changes in agricultural practices have helped in achieving food production
targets and have virtually eliminated the risk of famine, which was not uncommon
during pre-independence year. However, the Indian farmers in addition to their
traditional health problems such as malnutrition, infectious diseases etc. are
exposed to a number of hazards such as exposure to chemicals, toxic plant
products and ergonomic problems resulting from change in the agricultural
practices. Injudicious use of pesticides has resulted in occupational and
environmental health problems and ecological imbalance. The acute effects of
the chemical pesticides are very well known, however, their chronic health
effects, such as carcinogenic effects, teratogenic effects, mutagenic effects etc.,
resulting from repeated low dose exposure have not understood fully. There is
greater use of persistent pesticides such as DDT, BHC, endosulfan etc.
Injudicious and indiscriminate use of chemical pesticides has resulted in health
hazards to man, development of resistance in pests to pesticides leading to a
vicious cycle of use of greater dose resulting in emergence of new resistant
species and pest resurgence due to destruction of natural enemies, pesticide
residues in food, water, soil and fodder, poisoning of wild-life and live stock and
ecological imbalance. Large number of Indian farmers continues to use
traditional tools such as hoes, sickles, manual weeders etc. These tools are
designed by the local artisans. There is great scope for improving design of these
basic tools to make them more efficient and safe. The farmers need to be
educated about the hazards involved in using the newer technique and the
methods of the prevention.
10
Occupational Health Problems of Agricultural Workers in India - An Overview
References
1.
Indian Labour statistics -1994, Labour Bureau, Ministry of Labour, Simla, 1996.
2. Christinsen E.H. Man at work - Studies on the applications of physiology to
working conditions a sub-tropical country. International Labor Organization,
Geneva, 1964.
3.
Rajak R.L., Diwakar M.C. and Mishra M.P. Pesticide Information July-Sept 1997;
pp. 23-32.
4.
Bami H.L. Pesticide Use in India-Ten Questions.1996, Pesticide Information, Oct
-Dec 1996, pp 19-27.
5. Kashyap S.K and Gupta S.K. Effects of ultra low volume aerial spray of
phosphomidon (OP insecticide) on human volunteers: A field study. Ind. J. Med.
Res. 1976; 64:579-583.
6. Saiyed H.N., Sadhu H.G., Bhatnagar V.K., Dewan A.., Venkaiah K. and Kashyap
S.K. Cardiac toxicity following short-term exposure to methomyl in spraymen and
rabbits. Human Exp. Toxicol., 1992; 11: 93-97.
7. Nag P.K. and Pradhan C.K. Ergonomics in the hoeing operation. Int. J. Indust.
Ergonom. 1992; 10: 341 -350.
8. Nag P.K., Goswami A., Ashtekar S.P., and Pradhan C.K. Ergonomics in sickle
operation. Appl. Ergonom. 1988; 19:233 - 239.
9. Nag P.K. and Chatterjee S.K. Physiological reactions of female workers engaged
in Indian agricultural work. Human Factors 1981; 23:607 - 614.
10. Nag P.K. and Datt P. Effectiveness of some simple agricultural weeders with
reference to physiological responses. Human Ergol., 1979; 8:13-21.
11. Weizencker R. and Deal W.B. Tobacco cropper’s sickness. J. Florida Med. Assoc.
1970; 57: 13-14.
12. Ghosh S.K., Parikh J.R., Gokani V.N., Rao N.M., Kashyap S.K., and Chatterjee
S.K. Study on occupational health problems in agricultural tobacco workers. J.
Soc. Occup. Med. 1980; 29:113-117.
13. Ghosh S.K., Saiyed H.N., Gokani V.N., and Thakker M.U. Occupational health
problems amongst workers handling Virginia tobacco. Int. Arch. Occup. Env.
Health 1986;58:47-52.
14. Ghosh S.K., Gokani V.N., Parikh J.R. Doctor P.B. Kashyap S.K., and Chatterjee
S.K. Protection against “Green Symptoms” from tobacco in Indian harvesters: A
preliminary intervention study. Arch. Env. Health 1987 : 42:121-124.
ROHC-WHO Trg. Prog. On Occ. HeaJth in Agricultural Sector, Feb. 8-12,1999: LN.-2
Clinical Approach To Occupational Asthma
Dr. OMPRAKASH
St. Martha's Hospital, Bangalore
Occupational asthma is being reported, elucidated and increasingly
appreciated in recent years. Progressive industrialisation in the global context is
exposing workers to a variety of potentially allergenic substances at work.
Consequently, it is not surprising that an ever increasing number of cases of
occupational asthma is being reported. The accurate diagnosis of occupational
asthma is crucial from many points of view. As early as in 18th century,
Ramazzini recognized that workers sifting grains developed cough and wheezing;
is rightly called the father of occupational medicine as he encouraged his students
to add work history to the other points elicited.
Occupational Asthma (OA) can
be defined as variable air flow limitation and air way hyper-sensitiveness due to
causes attributable to the work place. OA can be caused by both allergic and
non-allergic causes. The prevalence of OA is very variable as reported from
different parts of the world. This variation is due to many factors including the
nature of the allergen, diagnostic criteria etc. In fact, within a given industry
varying prevalence rates are often noted. Another confounding factor would the
so-called "healthy worker effect” wherein the worker with OA leaves the
occupation due to increasing illness. Consequently one has to describe
prevalence rates in relation to a given industry at a given point of time. Over the
past 50 years, more than 200 agents have been shown to be capable of causing
occupation-related asthma. In the initial years it was felt that high molecular
weight glycoproteins were the main causes; in recent years it has been
demonstrated adequately that low molecular weight substances also can cause
this syndrome by acting as haptens. Depending on the allergen involved
prevalence rates of OA have varied from as low as 2% too as high as 30% in
various studies. For instance, Western Red cedar workers have a prevalence of
5% while acid anhydrides can cause OA in about 20% of workers.
Mechanisms
Several mechanisms are implicated in the causation of OA. These
The latter
include both immunology and non-immunology mechanisms,
mechanisms include the following:
a)
Stimulation of irritant receptors by toxic or irritant substances (e.g. plicatic
b)
Activation of serum complement by classical or alternate pathway (e.g.
Western red cedar)
Direct pharmacological effect (e.g. TDI)
c)
acid)
2
Clinical Approach To Occupational Asthma
Most of the immune mediated OA is due to IgE mechanisms. The role of
proteins, glycoproteins and polysaccharides in the causation of OA in various
situations has been abundantly demonstrated. In recent years it is known that
several agents which are low molecular weight substances can act as haptens
and induce allergenicity by combining with serum proteins. In some cases the
possible role of lgG4 is being investigated in recent years.
Evaluation of OA from the clinical view point
The evaluation of a subject possibly suffering from OA begins when the
clinical suspicion is raised by primary care physician that a given case of asthma
may indeed be due to an occupational exposure. In such a case, a series of
systematic steps have to be taken to establish the causal relationships between
the occupational offending agent and the subject's asthma.
History
A comprehensive and careful history has to be elicited whether there is a
sufficient possibility that a given case is one of OA. Workers are often unaware of
the substances that they are exposed to and therefore the clinician has to
visit the workplace and observe the work environment in a critical fashion with a
discerning eye. The factory managers and factory Medical Officer can
provide invaluable information as to the possible agents that can cause OA.
These agents have to be documented. In our country, there is lack of industrial
hygienists that can provide a lot of help in this regard. Consequently, the clinician
has to do a substantial amount of study of the literature to know whether a given
substance has been already documented as a cause of OA. In cases where no
such information is available, the task becomes more formidable and challenging.
A careful history and workplace survey will often will be very helpful in
narrowing down the possibility of causal agents. In case the OA is suspected in a
non factory environment (such as an industry which is community based both in
the governmental and private sectors), an epidemiological study is needed in the
suspected worker population as well as a control population; such a study will
afford important information to the clinical research worker that indeed there is a
higher prevalence of asthma in the occupation related population.
After documenting these data, the clinician proceeds with the further
and important history elicitation to whether the asthma is likely to be due to the
agent at the work environment. In this context it is important to realize that the
period needed to sensitize the individual to a given occupational allergen may
vary enormously. This latent period can be few months (e.g. platinum salts),
3
Clinical Approach to Occupational Asthma
about 2 years (e.g. DTI), 4-5 years (e.g. colophon) and over ten years (e.g., silk
allergens) factory workers rendering clinical analysis more complex.
While eliciting history, it is also necessary to enquire about possible
exposure to allergens at places other than the work situations (secondary
occupation or at home) as well as due to some hobby being pursued by the
subject. Location of a known strong sensitizes in close proximity has also to be
looked into; it is known that people living very close to factory where DTI is used
may get sensitized and develop disease in due course of time due to "secondary
exposure". In the clinical context, it has to be understood that the clinical patterns
of asthma are variable. These include the immediate asthmatic response, the
delayed response, the dual asthmatic response as well as recurrent (oftennoctumal) asthma after a single exposure to the offending substance. This makes
the clinical diagnosis of OA more difficult as there is no definite temporal
sequence, which is usually associated with the occurrence of allergic responses.
Lung Function Tests
Estimation of PEFR and FVC and FEV1.0 are commonly used in the
context of OA. Apart from base line measurements one has to perform serial
measurements of these parameters while the subject is at work. PEFR records
both at work and at home frequently may provide valuable information. More
important would be the "off and on " measure of PEFR while the subjects stays
away from work for a few days and returns to work; a sudden dip in PEFR which
remains low during the days of occupational exposure argue strongly in favor of
OA.
Lung function tests are also used during bronchial provocation (both non
specific and specific) and are the gold standard in the diagnosis of OA. One has
to be aware of false negative results due to concomitant optimal therapy of
asthma.
Skin Tests and Serology
If an immunologic basis is suspected, suitable antigens have to be
prepared from the suspected allergenic substances and used for prick tests. This
requires collaboration with a basic scientist and his laboratory. After prick tests
conducted among the subjects with suspected OA as well as controls in the same
work environment, one can proceed to study the specific IgE levels against the
suspected antigens. Demonstration of elevated levels of specific IgE antibodies in
a subject, however, does not always correlate with clinical illness. These factors
have to be correlated and viewed in the clinical context.
4
Clinical Approach To Occupational Asthma
Bronchial Provocation Tests (BPT)
In order to be certain that one is dealing with OA, both non-specific BPT
(with histamine and methacholine) and with a very dilute form of suspected
allergen (specific) has to be performed. This is not always feasible in our
context and conditions. It must also be bome in mind that while most cases of OA
occur in subjects with past bronchial hyper-reactivity and history of atopy, there
are instances where previously non-atopic subjects have also developed OA after
a longer latent period.
Epidemiologic Evaluation
Apart from the evaluation of the individual workers with OA, it is
essential to perform epidemiologic surveys to ascertain the prevalence of OA in a
given industry. The most important aspect of such evaluation is the generation
and use of comprehensive questionnaire. This will be of crucial importance. The
second aspect is that of serial PEFR and other functional measures performed
along the section of the workers (both symptomatic and asymptotic).
These
measures have to be both at work and while away from the workplace
environment for specified periods of time. Such observations have to be made in
an objective manner, with clinical symptom scores as well as PEFR
measurements.
Management
The principles of management in cases of OA are clear but their execution
is most difficult. To the extent possible, cessation of exposure to the offending
substance in proven cases is the best measure. Here, it is important to realize
that the sooner such cessation occurs after the development of symptoms, the
better are the chances clinical remission in asthma. Studies have shown that after
a long period of repeated exposures, the bronchial hyper responsiveness remains
for years after cessation of exposure. The worker may either leave and seek an
entirely new occupation or may be given a job in the same industry away from the
exposure to the allergenic insult. Obviously, these steps have social economic
and medico-legal implications and problem solving needs close cooperation of the
worker, the factory Medical Officer, the personnel manager as well as the clinician
involved in the assessment of these cases.
As it is known that atopic subjects are more likely to get sensitized to
known and potent substances capable of causing OA, screening of these subjects
and counseling them before they seek a job is very important.
Such pre
employment screening as a preventive step is essential.
5
Clinical Approach to Occupational Asthma
History, skin prick test with a battery of common prevalent allergens and
PFTs will allow detection of substantially atopic subjects. But such facilities are
not widely available at this time in our country.
Medical management of OA is similar to management of any asthmatic.
Use of inhaled bronchodilators, inhaled chromolyn and inhaled steroids as well as
judicious use of short courses of systemic steroids help in reduction of morbidity.
But subjects on such long-term treatment need to be watched periodically for
deterioration in lung functions as well as evidence of progression of poorly
reversible airflow limitation.
Though it has long been recognized that occupational asthma is a disorder
with medico-legal implications in terms of compensation, this aspect has not
received sufficient attention in our country. In some of the Western countries
some of the documented OA cases are compensable by appropriate legislation.
ROHC-WHO Trg. Prog. On Occ. Health in Agricultural Sector. Feb. 8-12,1999
Occupational Health Aspects In Sericulture
DR. S.B.DANDIN
Director, Karnataka State Sericulture
Thalaghattapura, Bangalore -560 062.
Research
and Development Institute,
Sericulture industry in India is an agriculture based cottage activity being
practiced since last 200 years by millions of rural families. Because of its high
employment potential; good returns; low initial investments and simple techniques
involved, more than 5 million people living in 50,000 villages are deriving their
livelihood in different activities of sericulture. India, the second largest silk producer
in the world accounting for 12% of raw silk production (13,000 M.T.) is also a
major silk consumer. Silk has become the part of Indian culture and the silk
occupies a prestigious and unique place in every household of the country. More
than 90% of the raw silk produced in the country is consumed domestically and
majority of it is used in production of sarees. In the country major silk producing
states are Karnataka, West Bengal, Andhra Pradesh, Tamil Nadu and Jammu and
Kashmir. The details of sericulture industry are given in Table -1. Of these,
Karnataka is the leading producer and accounts for more than 60% of the country's
production and Bangalore is called as the Silk City of the country.
Silk yam and fabric production is a synthesized activity comprising of 4
major activities namely i) Mulberry (Food plant) cultivation to produce leaf which is
the sole feed for silk worm (Bambyx Mori) ii) Silk worm rearing to produce cocoons
iii) Silk reeling to produce raw silk yam and iv) Silk weaving and finishing (Figure 1). Of the four activities first two are paracticed by rural agrarian families and the
latter two are mostly confined to specific localized centers and practiced by
landless and large by non-farming families.
Since sericulture is a cottage activity involving traditional methods, it too
has some occupational health problems similar to many other occupations. In
addition to several advantages of the industry, the important health problems
being faced by population involved in different activities of the industry are
discussed briefly along with their probable solutions.
Breathing Disorders
It has been known for a long time that persons engaged in the process of
silk work egg production (Grainage activities) are at risk to develop bronchial
asthma believed to be allergic in nature ( Harindranath et al,
2
Occupational Health Aspects In Sericulture
1985). Asthma is triggered by fine scales in the air released by the
fluttering of the silk moth. Male silk worm moths contribute more for release
of scales from their bodies as they flutter more frequently during mating.
People working in pairing, depairing etc. are prone to the inhalation of
scales and develop allergy. This can be prevented by wearing masks
consisiting of three layers of muslin cloth. The presence of exhaust fans
in the pairing/oviposition rooms would reduce the concentration of scales in
the given environment. Another area of hazardous activity is inhalation of
acid fumes during acid treatment of bivoltine eggs and dyeing of silk fabrics
using acid-baths in dyeing units. This also causes respiratory disorders
for persons working in egg treatment and dyeing units. Therefore, care
should be taken to avoid inhalation of acid fumes by providing exhaust fans
for grainages and dyeing units and also proper ventilation should be
provided to facilitate quick dispersal of acid fumes from the room.
In sericulture, formalin and bleaching powder are extensively used as
general disinfectants to destroy germs in rearing houses and appliances.
Use of formalin without certain precautionary measures causes burning of
eyes, mucous secretions and peeling out of skin. Bleaching powder solution
at higher concentration (>5%) causes similar hazards as hazards of
formalin. Therefore, use of face masks, hand gloves and gum shoes are
suggested during disinfecting the rearing room and appliances.
The
application of dust formulation like sanjeevini, suraksha or RKO powder and
Uzi powder cause respiratory disorders and burning of eyes. Hence,
protective cover for nose and mouth while working is advised.
During silk reeling, asthma is caused by the smoke emitted from cocoon
cooking basins with fire wood and the stench from steam and vapour arising
from fluids released from the pupal body. A few reports regarding the
incidence of occupational asthma in sericulture are available from China
and Japan.
In India, a clinical survey in 1985 involving 2 silk filatures
reveled that 36% of the total workers were suffering from bronchial
asthma. It also showed that for 16.9% of the workers it was only due to the
air-bome antigens originating from silk worm cocoons and pupae and hence
their suffering is of occupational origin.
1.
Skin diseases
The workers who are engaged in silk reeling units are more prone to fungal
and other skin infections like dermatophytosis (ring worm infection) due to
constant immersion of hands and during in hot and turbid water. This water is
often placed with certain chemicals to improve the colour or quality of silk. The
3
Occupational Health Aspects In Sericulture
floor of most of the silk rearing units are wet due to constant water usage
without proper drainage. In such circumstances feet get infected due to
continuous contact with damp floors due to improper and unhygienic drainage
system in reeling units.
Unless the whole process of reeling is mechanized, not much can be done to
avoid immersing the hands in hot water during reeling and cooking. An
antifungal skin ointment to be rubbed on hands and feet for preventing skin
diseases and using small forceps to lift or cast out cocoons during reeling
could be encouraged which may however, affect reelability/productivity.
As per the advice of silk reeling experts, wearing of gloves all day long is
not safer as this would prevent the hands from aeration and would itself
lead to fungal disease. Hence, good ventilation, proper drainage to ensure
minimum dampness, use of slippers, regular use of ointments and proper/
quick disposal of waste cocoons would prevent these health problems to a
greater extent.
The separation of palade layer / waste cocoons from pupae is an infamous
procedure by standing ankle deep dirty and foul smelling water in which
spent cocoons have been dumped. Further, separating palade layer from
the dead pupae by squeezing the individual cocoons by hand is a
degrading task.
2.
Other Hazards
Mulberry is prone to be attacked by certain pathogens, insect and non insect
pests. Several pesticides have been recommended for using in mulberry
gardens to check the incidence of diseases and pests. The use of
pesticides causes severe skin bums while preparation of spray solution and
also during the course of application. Therefore precautionary measures
like use of hand gloves; devices, leak proof sprayers; glass rod/stick for
stirring the liquids; face masks etc. have been suggested to avoid direct
contact with pesticides. The people involved in weaving units do have
certain problems due to sound pollution. The over-pick and under-pick power
looms have more beat up sound which sometimes exceeds 150 decibels.
This may induce gradual deafness to people involved in weaving units.
However, this problem is not noticed in versatile machines with jet/rapier
looms which produce lesser sounds. Use of cotton ball as ear plugs to
avoid more sound is advised. People involved in fabric dyeing industries too
are prone to certain health problems as they directly deal with dyes which
4
are basically chemicals and some of them are harmful to skin, some of the
dyes have been also banned for usage due io some health problems as
they are reported to be carcinogenic, Hence, use of vegetable and eco
friendly dyes has been recommended.
Silk consumer may not be aware of different biological and technological
aspects through which the final beautiful fabric which adores the human
beauty is prepared. Many hands toil to achieve the final product who live
anonymous and deprived of the consumer appreciation, yet are satisfied for
the work they do.
However, the recent government policies both at state and central levels
must bestow their attention to organize special units in concerned hospitals;
arrange health camps; periodical check up etc. to the workers engaged in
the industry so that the suffering of these could be minimized if not fully
solved.
STATEWISE MULBERRY SERICULTURAL STATISTICS FOR 1997-98
STATE
Andina lYadcsh
Assam
Arunachal Pradesh
Bihar
Gujarat
I limachal lYadesh
I Ian ana
Jmniu & Kashmir
Karnataka
Kerala
Madhya Pradesh
Maharashtra
Manipur
Mizoram
Meghalaya
Nagaland
Orissa
Punjab
Rajasthan
Sikkim
Tamil Nadu
Tripura
Uttar Pradesh
West Bengal
TOTAL
Area
under
mu I hern
(He)
38084
2813
____ 97
474
____ 63
356
20
4717
166000
1164
2043
706
25975
550
135
___ 6_12
___
620
134
____ 24
9491
656
5665
21358
282244
627.41
4.64
0.54
6.08
0.10
4.68
0.06
31.62
1886.33
0.78
11.3
__ 5.^
13.92
3.08
1.00
0.18
__ 2.78
0.94
0.46
PRODUCTION OF
Reeling
Raw
Silk
Cocoons
silk
waste
Tons
Tons
Tons
24809
2696
725
150
14.65
5
16
1.38
113
8.50
2
___ 2
0.12
114
14.40
4
___ 1
neg.
785 _ 84
30
80656 9236 2495
31 __ 3 __ 1_
143
14.35 __ 5
161
16.12 __ 9
497 49.10
14
17
1.67
14
1.38
neg.
6
_0.60
4
_?6__ 5.60
30
__ 3_
1
10
0.33
Filature
& Cottage
basins
Nos.
1193
91
___ 1_
___3
12
30
139.67
0.71
13.19
600.23
3355.23
601
5705
601
232
25
2.46
2.46
1
324
40.5
40.5
8
13800
1254
1254 464
127495 14048.16 4000
3379
__ 32
115
1200
26427
Dfls.
Lakhs
Charaka
Nos.
1646
219
16
55
392
19774
25089
40
21
75
97
10
500
11
15
17
2
24
Hand
Looms
Nos.
Power
Looms
Nos.
16000
290
23300
4000
225
5000
590
40000
6000
34224
60000
12800
182325
Figures represent 1996-97
Sericulture
Families
2626
16590
NA
1314
1357
354
__ 60
1812
140
2300
819
114
___ 6
4985
278
2017
1580
59528
NA
294777
Nos._____
9377
123458
7103
175631
194
2600
4770
165000
127 _____ 900
1687
6666
10000
5000
1500
22800
No. of Seri
culture
Villages
Nos.
5000
29590
15378
3284
2900
200
NA
7270
39805
1088
1060
____20
68871
1740
20597
80194
1031439
SILK PRODUCTION CYCLE
MULBERRY
CUTTING
MULBERRY
SAPLING
MULBERRY
FIELD
■?
FIELD
MAINTENANCE
LEAF
HARVESTING
CULTIVATION —
PRUNING-------IRRIGATION —
FERTILISATION
EGG
INCUBATION
SILKWORM
r
REARING
z
SILKWORM EGG COLD
STORED AND ACID
TREATED
SILKWORM BREEDING
AND MULTIPLICATION
DISINFECTION
STNDS
TRAYS
MOUNTING AIDS
FRESH COCOONS
DRYING &
-> STORAGE
TRANSPORT &
MARKETING
SORTING &
STIFLING
■>
SPINNING
SAMPLING
SILK
RAW SILK
REELING
WASTE
SPUN SILK
<-
RAW SILK
MARKETING &
- STORAGE
-
DEYING
THROWING
5 WEAVING
$
7
WEAVING
7
PRINTING
FINISHING
MARKETING
I
ROHC-WHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999: L.N.-3
Siiicosis And Silico-Tuberculosis
Dr. H.N. SAIYED
Director, National Institute of Occupational Health, (Indian Council of Medical
Research), Meghani Nagar, Ahmedabad-380 016.
Silicosis is an occupational lung disease attributable to the inhalation of silicon
dioxide, commonly known as silica, in crystalline forms, usually as quartz, but also as
other important crystalline forms of silica, for example, cristobalite and tridymite. It is
the most ancient and commonest of all occupational diseases and claims larger
number of lives than any other occupational disease. Even today, it continues to be
among the most serious occupational diseases. The crystalline free silica, the agent
responsible for the causation of silicosis, is one of the most powerful fibrogenic matter
found in Nature. It forms about 12% of the earth's crust and is next only to feldspar in
abundance. Mining and tunneling are therefore occupations most closely related to
the hazards of silica exposure. The sand stone industry, cement industry, quarrying,
‘
’*•2 ”-'"q ~
"
-
Generation of a large cloud of dust
during the cutting of slate pencil at
Mandsaur (M.P.)
the granite industry, slate quarrying and dressing, grinding of metals, iron and steel
foundries, silica milling, flint crushing and the manufacture of abrasive soaps and
glass also involves occupations which may lead to silicosis. Some of the lesser
known occupations which are important from hazard point of view and peculiar to
India and some other developing nations are slate pencil cutting, agate
polishing etc. In India there are about 1.7 million workers engaged in mining of
various minerals, iron and steel industries, cement industry, manufacturing of glass,
foundries, quarries etc. All these industries involve potential risk of exposure to
siliceous dust and subsequent development of silicosis.
Amongst all the atmospheric contaminants encountered in industry, free silica
has the dubious distinction of being the only dust which predisposes significantly to
the development of tuberculosis. The occurrence of silicosis and tuberculosis
together is known as 'silico - tuberculosis'. Susceptibility of silicotic patients to
2
Silicosis And Silico-Tuberculosis
tuberculous infection has been established since the beginning of this century. The
potentiating effect of free silica on tuberculosis was experimentally proved by
Gardener in 19291. He also produced an experimental evidence that in the presence
of quartz, even normal nonpathogenic strains of mycobacteria, could produce
tuberculosis. Later experimental studies and field investigations have confirmed that
the atypical mycobacteria like myco. Avium and myco. Kansasii, are frequently
responsible for tuberculous infection in silicotic patients. These atypical mycobacteria
are poorly sensitive to most of the anti-tubercular drugs and therefore, the prognosis
in these cases is poor.
The prevalence of tuberculosis has direct relationship with the concentration
of free silica dust in the work environment. The incidence of tuberculosis increases
with the severity of silicosis. High prevalence of tuberculosis has been reported from
the industries involving potential risk of silica exposure.
Magnitude of the problem: Precise data on industry wise incidence of silicosis and
tuberculosis are not available. However, there are strong reasons, from some of the
survey works, to believe that the incidence of these diseases is very high in many
industries. The problem of these diseases is more severe in small scale and cottage
industries because of certain characteristic features of these industries. Most of these
units are run by small entrepreneurs with limited financial resources and inadequate
technical know how. The labour forces are unorganized and lack the ability of
collective representation against exploitation like long hours of work, low wages,
unchecked work place hazards etc. Medical facilities are usually non-existent. Due to
high labour turnover and absence of periodical medical examinations, cases of
chronic diseases like silicosis and tuberculosis usually pass unnoticed. To make the
situation worse, most of these units are beyond the purview of legal provisions like
Factories Act and ESI Act which are aimed at safeguarding health, safety and
welfare of the industrial workers.
In Table 1 the findings of the author as regards to the prevalence of silicosis
and tuberculosis in some of the small scale and cottage industries have been
summarized. The industrial hygiene study in the industries mentioned in the above
table showed the dust levels several times higher than the prescribed threshold limit
value (TLV). It is seen from the above table that the prevalences of silicosis and
tuberculosis were very high. The prevalence of tuberculosis varied from 15% to
34.8%. In the slate pencil industry, despite very high prevalence of silicosis, the
prevalence of tuberculosis was lower than that in other industries. In this industry,
highest levels of silica dust were found and the follow up examination of workers
showed rapid progression of the disease resulting in high mortality in relatively short
duration2,3 and Chatterjee 1985). It is quite likely that many workers suffering from
silicosis might have succumbed to the disease before developing tubercular infection.
On the other hand, it is also likely that many cases of tuberculosis might have been
masked by silicosis.
3
Silicosis And Silico-Tuberculosis
Table 1 : Prevalence of silicosis and tuberculosis in some small scale,
and cottage industries.
Industry
Silicosis
No (%)
Tuberculosis
No (%)
Slate Pencil Cutting
(n^593)
324 (54.7)
89 (15.0)
Ceramic Industry
44 (15.1)
44(15.1)
Agate Grinding & Polishing
(n=468)
136 (29.1)
131(30.1)
Stone Cutting (n=89)
17(19.1)
31(34.8)
(n=292)
The diagnosis of tuberculosis in silicotic patients is relatively difficult because
the silicotic lesions may be indistinguishable from the tuberculosis on radiographic
examination.
The data on relationship between severity of silicosis and occurrence of
tuberculosis in slate pencil cutting industry and ceramic industry have been pooled
and presented in table 2. It is evident from the table that the prevalence of
tuberculosis increase with increase in the severity of silicosis.
Table 2: Prevalence of tuberculosis according to severity of silicosis.
Severity of Silicosis
Number of cases
Tuberculosis
Category 0
517
44 (8.51)
Category 1
161
24 (14.91)
Category 2
145
35 (24.14)
Category 3
62
25 (40.32)
Clinical Features:
It is important to emphasize that there may be no symptoms
even though the radiographic appearances may suggest fairly advanced silicosis.
Dyspnoea on exertion is considered to be the most frequent and directly related
symptom of silicosis. The severity dyspnoea increases with progress of the disease.
In the absence of complicating disease (e.g. tuberculosis), it is rarely complained off
at rest. Slight unproductive cough is complained at the initial stages, later on the
quantity of sputum increases. The symptom complex may resemble chronic
bronchitis. Excessive sputum production is due to bronchial catarrh brought about by
4
Silicosis And Silico-Tuberculosis
PMF: Male, 22 years,
worked as a slate
pencil cutter for 9
years. Second X ray
was taken after 8
months. Died shortly
after the second x
ray.
&
V
L *
4-8-1981
*
7^-198,2
chronic dust exposure and some times it is due to secondary bacterial infection of the
devitalized lungs. Chest pain and haemoptysis (blood in sputum) indicate possibility
of complication like tuberculosis.
Chest Radiography: Chest radiography is the most important tool for the diagnosis
of silicosis. There appears clear relationship between total dust exposure and
severity of radiographic changes. In the initial stage, there is ‘reticulation1 of lung fields
due to thickening of perivascular and inter-communicating lymphatics. The
radiographic diagnosis of silicosis can be made with some degree of certainty only
after the appearance of nodules. The silicotic nodules are 2-5 mm in diameter,
homogenous density and usually bilaterally symmetrical. On continuation of dust
exposure, the nodules increase in size and number and eventually cover most parts
of the lungs. Sometimes the silicotic nodules unite and form ‘conglomerate shadows'.
These conglomerate shadows are sometimes described as progressive massive
fibrosis (PMF), indicating the future course of disease (See above figure).
Sputum examination for Tubercle Bacilli: Surest
method
of
establishing
diagnosis of pulmonary tuberculosis is the demonstration of bacilli in sputum.
However, the recovery of tubercle bacilli in the sputum of patients suffering from
silico-tuberculosis is difficult. This is because of "walling in" of tubercle foci by silicotic
fibrosis which prevents the discharge of tubercle bacilli in the sputum. Large number
of cases of tuberculosis remain undiagnosed during life is evidenced from the fact
that very high prevalence of tuberculosis is usually observed in post mortem study of
industrial population occupationally exposed to high levels of silica. Gardner4 found
evidence of tuberculosis between 65% and 75% silicotics from various industries.
Yuang Ching Co5, Barras6 and Schyczmykiewicz et al7 found post-mortem evidence
of tuberculosis in 48%, 50% and 52% in silicotics respectively. James8 and Rivers et
al9 found evidence of tuberculosis in 40% and 35% cases of progressive massive
fibrosis (PMF) respectively at autopsy examination. However, during life, the
recovery rate of tubercle bacilli from sputum of the South Wales miners with PMF
was very low, i.e. 1.1%(Cochrane et al10) and 2.7% (Marks11).
5
Silicosis And Sillco-Tuberculosis
Differential diagnosis between silicosis and tuberculosis: For the diagnosis of
silicosis, satisfactory occupational history of silica exposure is most important.
Occurrence of silicosis in the absence of occupational exposure is rare12.
Radiologically, silicosis and miliary tuberculosis closely resemble each other,
however, miliary tuberculosis in adults is rare and the patient is toxaemic. The
nodules in miliary tuberculosis whether small or large, are less than those of silicosis.
The radiographs of silicosis usually show increased translucency as against general
loss of translucency in tuberculosis. In general, the severity of symptoms in a patient
suffering from simple nodular silicosis is much less as compared to the one suffering
from miliary tuberculosis. The
distinction between adult type (post-primary)
tuberculosis and conglomerate (PMF) radiological shadows is some times very
difficult. However, the conglomerate shadows of silicosis do not show cavitation.
Associated complications like pleural effusion and distortion of the intra-thoracic
organs due to fib ms is are usually not observed in conglomerate shadows.
The above description is that of classical silicosis. However, in some
cases, silicosis may develop within a few months to 2 years of massive silica
exposure. Dramatic dyspnoea, weakness, and weight loss are often presenting
symptoms. The radiographic findings of diffuse alveolar filling differ from those in
the more chronic forms of silicosis. Histologic findings similar to pulmonary
alveolar proteinosis have been described, and extrapulmonary (renal and
hepatic) abnormalities are occasionally reported. Rapid progression to severe
hypoxaemic ventilatory failure is the usual course.
Therapy, Management of Complications and Control of Silicosis13 There is
no specific treatment of silicosis, the therapy is directed largely at complications
of the disease. Historically, the inhalation of aerosolized aluminium has been
unsuccessful as a specific therapy for silicosis. Polyvinyl pyridine-N-oxide, a
polymer that has protected experiment animals, is not available for use in
humans. Recent laboratory work , particularly in China, with tetrandrine has
shown in vivo reduction in fibrosis and collagen synthesis in silica exposed
animals treated with this drug. However, strong evidence of human efficacy is
currently lacking, and there are concerns about the potential toxicity, including
the mutagenicity, of this drug. Because of the high prevalence of disease in
some countries like China, India and many other developing nations,
investigations of combinations of drugs and other interventions continue.
Currently, no successful approach has emerged, and the search for a specific
therapy for silicosis to date has been unrewarding.
Further exposure is undesirable, and advice on leaving or changing the
current job should be given with information about past and present exposure
conditions. In the medical management of silicosis, vigilance for complicating
infection, especially tuberculosis, is critical. The use of BCG in the tuberculin-negative
silicotic patient is not recommended, but the use of preventive isoniazid (INH) therapy
in the tuberculin-positive silicotic subject is advised in countries where the prevalence
6
Silicosis And Silico-Tuberculosis
of tuberculosis is low. The diagnosis of active tuberculosis infection in patients
with silicosis can be difficult. Clinical symptoms of weight loss, fever, sweats and
malaise should prompt radiographic evaluation and sputum acid-fast bacilli
strains and cultures. Radiographic changes, including enlargement or cavitation
in conglomerate lesions or nodular opacities, are of particular concern.
Bacteriological studies on expectorated sputum may not always be reliable in
silicotuberculosis. Fiberoptic bronchoscopy for additional specimens for culture
and study may often be helpful in establishing a diagnosis of active disease. The
use of multidrug therapy for suspected active disease in silicotics is justified at a
lower level of suspicion than in the non-silicotic subject, due to the difficulty in
firmly establishing evidence for active infection. Rifampin therapy appears to
have enhanced the success rate of treatment of silicosis complicated by
tuberculosis, and in some recent studies response to short-term therapy was
comparable in cases of silicotuberculosis to that in matched cases of primary
tuberculosis. Ventilatory support for respiratory failure is indicated when
precipitated by a treatable complication. Pneumothorax, spontaneous and
ventilator-related, is usually treated by chest tube insertion. Bronchopleural
fistula may develop, and surgical consultation and management should be
considered.
Prevention and Control of Silicosis and Silico-tuberculosis:
There is need for planning National strategy for the prevention and control of
silicosis and silico-tuberculosis. Country wide silico-tuberculosis control should
consist of two major components: 1. Definition of magnitude of the problem at
national level, and 2. Implementation of actual control measures.
Definition of Magnitude of the Problem at National level:
To plan and execute the national strategy for the prevention of silicotuberculosis the knowledge of total population at risk and number of people already
affected is very essential. The population at risk of silicosis can be roughly estimated
on the basis of available information on industries, their location, raw material and
industrial process and employment in each of them. This should be followed by
comprehensive industrial hygiene and epidemiological surveys in sample population.
After estimation of population at risk and identification of more vulnerable groups, the
industrial and medical surveys should be carried out. The industrial hygiene survey
shall include measurement of "total" and "respirable" dust at work places and the
qualitative analysis of dust samples. The tools of epidemiological survey are
recording of occupational history, clinical history and physical examination, chest
radiograph, sputum examination and spirometry. Chest radiography is the most
important single investigation having a high degree of specificity but relatively low
sensitivity. The history and physical examinations help in excluding other respiratory
diseases. The spirometry may help in appraisal of the functional loss. The results of
the sample surveys will help in identifying the thrust areas. The thrust areas may be
7
Silicosis And Silico-Tuberculosis
defined on the basis of number of people at risk and the severity of hazard. Industries
having moderate risk but employing a large work population e.g. the mines, or highly
hazardous industries employing smaller number of workers e.g. slate pencil industry,
agate industry, quartz grinding industry etc., fall in this category. For the reasons
already mentioned, there is a special need for looking into the problems of small
scale and cottage industries.
Implementation of Actual Control Measures:
The process of the control of silicosis consists of, (1) Dust control measures
and (2) Medical measures.
Dust control measures:
There is no silicosis without dust exposure, and the dust levels in work
environment correlates well with incidence of severity of the disease. Therefore,
elimination or suppression of dust in the work environment is the key in control of
silicosis. Each industry has its unique work process and therefore it is not possible to
have a single prescription appropriate to all. The general principles of dust control
measures include substitution of more hazardous substances with innocuous one,
isolation and enclosure of the sources of dust, use of wet methods wherever
possible, application of local and general exhaust, humidification of work environment
etc. Frequently, the management is found to share the misconception of laymen that
the supply of dust mask is sufficient for the prevention of dust related occupational
diseases in the industry. The personal protective equipments such as masks should
be prescribed only when all available methods of dust control measures have failed.
In fact, the dust masks are of little value when the dust concentrations are too high
for the dust particles will soon clog the pores in the filter resulting in a choking
sensation and discontinuance of the use of masks by workers. Moreover, the masks
are not suited for hot and humid climate.
Medical Surveillance:
As per the recommendation of WHO14, the medical screening
programme should be integrated and pursued with the environmental
surveillance programmes so that the results of both could be related to
reviews of measures taken to control the environment. The medical
examination is necessary because perfect knowledge does not exist as to
the safe level of exposure. Medical surveillance should be continued, not
as control method, but to verify the adequacy of dust control measures.
The medical measures for the control of silicosis and silico-tuberculosis
include pre-employment and periodical examinations, incorporating chest
x-ray, sputum examination for tubercle bacilli and spirometry. The
pre-employment medical examination will provide the baseline data for
each individual. The periodical medical examinations shall aim at early
detection of cases of silicosis and tuberculosis. The success of the
8
Silicosis And Silico-Tuberculosis
prevention programme will largely depend upon the active co-operation of
the workers at risk. Therefore, the need for health education of the workers can not
be overemphasized.
References:
Gardner L.W. Studies on experimental pneumoconiosis. Amer.. Rev. Tuber.
1.
20(1929) 833-875.
2.
Saiyed, H.N., Parikh, D.J., Ghodasara, N.B., Sharma, Y.K., Patel, G.C.,
Chatterjee, S.K. and Chatterjee, B.B., Silicosis in Slate Pencil Workers: I. An
Environmental and Medical Study. Am. J.Indus. Med., 8 (1985) 127-133.
3.
Saiyed, H.N. and Chatterjee, B.B. Rapid Progression of Silicosis in Slate
Pencil Workers: II. A FollowUp Study. Am. J. Indus. Med., 8 (1985) 135-142.
4.
Gardner L.W. 3rd Saranac symposium on silicosis. Trudeau.. Sch. Tuber.
Saranac Lake, New York, 1937.
5.
Yuang Ching Co. Silicosis in gold miners. Jour. Occ. Med. 5 (1963) 46-47.
6.
Barras G. Silico-tuberculosis in Switzerland. Schweiz. Med. Wsch. 100 (1970)
1802-1808.
7.
Schymczykicz, K., Czuraj H. and Kunski H. Pneumoconiosis in iron-ore
miners and ore enrichment plant personnel. Med Pracy. 21 (1970) 359-365.
8.
James W.R.L. The relation of tuberculosis to the development of massive
fibrosis in coal workers. Brit. Jour, Tuber. 48 (1954) 89-101.
9.
Rivers D. James W.R.L., Davis D.G. and Thomson S. Brit. Jour. Indus Med.
14(1959) 39-42.
10.
Cochrane A.L. Cox J.G. and Jarman T.F. Pulmonary tuberculosis in Rhodda
Each. Brit. Med. Jour. 2 (1952) 843-853.
11.
Marks J. Infective pneucomoniosis due to anonymous mycobacteria. Brit.
Med. Jour. 2 (1961) 1332.
12.
Saiyed, H.N., Sharma, Y.K., Sadhu, H.G., Norboo, T., Patel, P.D., Patel, T.S.,
Venkaiah, K. and Kashyap, S.K., 1991, Non-occupational pneumoconiosis at
high altitude villages in central Ladakh. Brit. J. Ind. Med., 48 (1991) 825-829.
13.
John E. Parker and Gregory R. Wagner SILICOSIS : Respiratory System in
ILO Encyclopedia of occupational Health & Safety. Ed. J.M.Stellman Vol.1
Pages 10.1-10.97 (Printed Version) 4th edition, ILO Office, Geneva, 1998.
14.
WHO Report on "Control of Pneumoconiosis (Prevention, Early diagnosis and
Treatment)". Rept. No. WHO/OCH/90.1, WHO, Geneva 1990.
ROHOWHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999. LN.-4
Toxic Lung Injury
DR. D. P. NAG
Officer-In-Charge, Regional Occupational Health Centre (Southern), I.C.M.R., Library
and Information Centre, Bangalore Medical College Campus, Bangalore -560 002.
INTRODUCTION
The respiratory tract represents a unique, vast battleground. With its high
surface area and rich vasculature and is in delicately balanced state of siege. The
upper respiratory tract is an important point of entry of toxins which may effect not
only the lungs but other organs as well. The outcomes of the assaults range from
minor irritation to respiratory insufficiency to life threatening systemic toxicities.
Inhalation is probably a most important route of exposure in the work place.
The list of potential toxins is legion including air pollutants, pesticides, cigarette
smoke, food grain dust, etc. Some exposures produce lung injury with a single
inhalation. Others may act insidiously taking effect only after many years of
exposure. However, as the toxic injury progresses the pathologic and clinical sequel
can be expected to form into one or more stereotypic patterns :
1. Irritant reversible effects on the lower / or upper respiratory tract.
2. Permanent damage to the airways.
3. Damage to the gas exchange units of the lungs.
4. Oncogenesis.
Some agents produce multiple effects for e.g. Asbestos can cause not only
pulmonary fibrosis but lung cancer as well. Cigarette smoke effects range from
chronic bronchitis to emphysema and lung cancer. Hydrogen Sulfide can produce
everything from upper airway irritation to pulmonary edema and respiratory paralysis.
Pulmonary Toxins And Respiratory Tract Anatomy
Deposition and retention of air borne substances are dictated partly by the
anatomy of the respiratory tract. The arbitrary subdivisions as nasopharyngeal,
tracheobronchial and pulmonary is to simple and most of the toxic agents tend to
effect in varying degrees the three subdivisions. The respiratory tract is more than a
series of interconnected tubes having more than 40 types of specialized cells, which
vary in their susceptibility to inhalation injury.
Epidemiological studies have suggested respiratory pathophysiology
associated with occupational exposure to grain dust. Workers from farm to grain
storage terminals experience dust exposures and possible lung disease from
2
Pulmonary Toxins And Respiratory Function
handling grain.
Grain storage workers are exposed to airborne dusts of
heterogeneous composition. Respirable dust levels are reported to be responsible for
observed adverse health effects.
DEPOSITION AND CLEARANCE OF INHALED SUBSTANCES
Gases and Aerosols basically are two main forms of pulmonary toxicants.
Aerosols are droplets of liquid or particles suspended in air or gas. The sight of
deposition of inhaled toxicant is largely determined by the solubility of the toxicants in
the aqueous layer of the respiratory mucosa. The toxicants that are extremely water
soluble such as Ammonia and Sulfur Dioxide will be deposited and removed
predominantly by the upper respiratory tract. The less soluble the toxicant the greater
the potential for damage at the level of the terminal respiratory unit.
The size of the toxicant particle is usually the predominant factor effecting
deposition although the particle density and shape contribute to the pattern. The
majority of the particles greater than approximately 10 microns in diameter or
successfully filtered out by the nasopharynx. Particles in the range of 0.5 to 3
microns are deposited predominantly in distal airways and alveoli. Particles less than
0.5 microns in diameter are mainly exhaled without significant deposition. Lung cells
vary in their susceptibility to toxic agents and are major determinants how inhaled
toxicants effect the respiratory tract. Similarly, particle clearance is of equal
importance in determining the toxic effects of inhaled agents.
TOOLS IN ASSESSMENT OF PULMONARY TOXICITY
1.
Occupational Exposure Assessment:
•
•
•
•
History
Materials safety data sheets
Insight investigations
Detection of minerals in the lung
Light microscopy
Electron microscopy
2.
Clinical examination
3.
Chest Imaging
3.1
Chest Radiography:
The chest radiograph is one of the cornerstones in the assessment of toxic
injuries to the respiratory tract. Although evidence of obstructive lung disease can be
3
Pulmonary Toxins And Respiratory Function
found on chest radiograph, the greater application pertains to toxic injuries, which
produce interstitial infiltrates, such as pneumoconiosis. Classically to look at are (a)
shape of opacities (e.g. irregular versus rounded); (b) size of opacities; (c) profusion
(the number of opacities per unit lung); (d) the extent and location of the infiltrates
(e.g. upper lobe versus lower love predominance); and (e) presence of ancillary
findings such as pleural plaques, adenopathy, pulmonary hypertension, cardiac
enlargement, and Kerley’s lines. These five main observations from the basis of a
formal reading system known as the International Labour Organization (ILO) 1980
Classification of Radiographs of the Pneumoconiosis. Although designed for the
systematic recording of radiographic changes caused by inhalation of mineral dusts,
the principles can be applied in reading films from any of the diffuse interstitial
diseases.
By this classification, small opacities (less than 10 millimeters in diameter) are
described as “rounded” as seen in diseases such as silicosis, or “irregular” as seen in
asbestosis. The letters “p”, “q” and T are used to subdivide rounded opacities
according to size - upto 1.5,1.5-3.0, and 3.0-10.0 millimeters, respectively. Similarly,
the letters “s”, T and “u” describe the predominant sizes of small irregular opacities.
In the classification system each radiograph’s opacities are classified according to the
most common and next most common shape and size. For example, “s/t” indicates
that the majority of opacities are size’s, and the second most common size is t.
profusion. The number of small rounded or small irregular opacities per lung zone, is
divided into four main categories from 0 through 3 and these are further divided along
a 12-point scale ranging from 0/- to 3/+. To score the extent of involvement, each
lung is arbitrarily divided into three zones by horizontal imaginary lines one third and
two thirds of the distance between the apex of the lung and the dome of the
diaphragm.
The ILO classification also systematically describes large opacities (greater
than 10 millimeters) as well as pleural plaques and other abnormalities. A set of
standard ILO reference films are routinely used by readers in judging the shape, size
and profusion of opacities of a given chest radiograph.
The opacity’s shape (round versus irregular) is of limited utility.
Most
interstitial lung diseases can present with a range of opacities from pure round to
reticular nodular to pure linear or irregular. Even in simple silicosis-the classic
example of rounded opacities - the opacities can assume a more reticular
appearance on the chest radiograph, depending on factors such as dust burden and
duration of illness.
Distribution of diffuse infiltrates may be of slightly greater predictive value,
although again there are many exceptions. Opacities are found throughout the lungs
in most interstitial lung diseases. However, in a number of toxicants-induced
4
Pulmonary Toxins And Respiratory Function
diseases there is lower lung predominance. Examples include nitrofurantoin-induced
disease, metallic mercury embolism, interstitial pulmonary edema, pulmonary fibrosis,
asbestosis, and talcosis . Relatively few of the diffuse interstitial lung diseases will
show upper lung field predominance, with two notable exceptions from the standpoint
of toxic inhalation: silicosis and chronic beryllium disease. Hilar adenopathy, with or
without “egg shell” calcifications, is seen in silicosis as well as in some cases of
coalworker’s pneumoconiosis and occasionally in chronic beryllium disease.
A pattern of acute pulmonary edema in a patient without trauma or heart
disease raises the specter of chemical exposure. The typical pattern will be that of
diffuse fluffy alveolar infiltrates but with a normal heart size. Drugs that can cause a
non-cardiogenic pulmonary edema pattern include amphotericin B, aspirin,
hydrochlorothiazide, lidocaine, major tranquilizers, opiates, and sedatives as well as
sympathomimetic agents. Alveolar hemorrhage is often indistinguishable from the
pulmonary edema pattern on chest radiograph. This can result from a number of
exposures including agents such as D-penicillamine and trimellitic anhydride.
The limitations of the chest radiograph need to be acknowledged. First, chest
radiograph often correlates poorly with the clinical activity of interstitial lung diseases.
For e.g. the chest radiograph may be markedly abnormal in coal workers who have
normal pulmonary function. A number of inhaled dusts may produce “benign
pneumoconiosis”. When dusts are radiodense, they produce radiographic changes
but with little or no pathologic or physiologic abnormality upon further investigation.
Conversely, some patients with significant pulmonary embarrassment have normal
appearing chest radiographs. Radiographically inapparent clinical illness can occur in
patients with farmers lung or other hypersensitivity pneumonitides, beryllium disease,
and asbestosis.
A second major limitation of the chest radiograph is its lack of specificity.
Many types of injury produce similar radiographic changes. This lack of specificity
prevents us from relying too heavily on the chest radiograph in differential diagnosis
of chest disease. For e.g. although it is classically taught that silicosis produces small
rounded opacities predominantly in the upper and mid-lung fields, there are many
cases described in which the disease may have lower lobe predominance with a
more reticular appearance on chest radiograph. Asbestosis is classically credited
with producing small irregular opacities in the lower lung fields; however, this disease
can produce mid- and upper lung field predominant disease. Even the presence of
pleural plaques, which may occupational medicine physicians equate with asbestos
exposure, has limited specificity. There are many pulmonary diseases (related or
unrelated to toxicological insult) which can produce bilateral pleural disease, including
silicosis, diatomaceous earth pneumoconiosis, and chronic beryllium disease.
Previous chest surgery or chest trauma may also confound the assessment of pleural
5
Pulmonary Toxins And Respiratory Function
disease. However, in the proper clinical context, presence of plaques and infiltrates
in an asbestos-exposed individual may be sufficient to diagnose asbestosis.
3.2
Gallium Scintigraphy
3.3
Computerised Tomography
4
Physiological assessment
4.1
Spirometry
4.2
Lung Volume Assessment
4.3
Gas Exchange
5
Endoscopy
6
Immunologic evaluation of pulmonary toxicity
The list of agents that can cause lung injury is legion and range from minor
irritant to carcinogens.
Clinical approach to the evaluation of suspected reactive airway disease
(Astnma), intestinal lung disease and common causes of occupational and
environmental lung cancer will be outlined in the presentation.
Further Suggested Reading:
1.
Olenchock SA, Christian David C, Jadith C Mull, Shen Yie and Lu Pei -lian.
“Airborne endotoxins ina rice production commune in the People’s Republic of
China”. J. Toxicol. Envt. Health 1984 : 13: 545-551.
2.
Mukherjee AK, Nag DP. “Environmental monitoring of grain dust in storage air
of Bangalore City”. Ind. J. Env. Prot. 1995 : 15: 501-503.
3.
Nag DP, Mukherjee
AK, Rajan BK, Nagarajan Lalitha, Ravibabu K,
Venkatesh CR, Sehar V. “Respiratory Function Among Grain Storage
Workers”. Ind. J. of Ind. Med. 1996 : 42(1) : 4-10.
Z2H -10°
rro &
05576
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1
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ROHC-WHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999: L.N.-5
Tuberculosis Among Agricultural Workers And Its Control
DR. (MRS). P. JAGOTA1
1 Director,
2
DR. V. K. CHADHA
Epidemiologist
National Tuberculosis Institute, 8, Bellary Road, Bangalore - 560 003.
TUBERCULOSIS is the world’s foremost cause of death from a single
infectious agent1 and annually there are about 3 million deaths from tuberculosis
(TB) all over the world2 with about 15% of these occurring in India alone3. The
brunt of the disease is borne by those in the age group4 of 15-59 years.
Approximately 6.7% of all deaths5 and 18.5% of deaths in the above age group6 in
the developing world are attributable to TB. An estimated one-third of the world
population is infected by M.Tuberculosis, with 95% of TB cases occurring in
developing countries. Among more than 900 million people in India today, every
second adult is infected with the tuberculous mycobacteria and each year more
than 2 million people develop active TB. At any point of time in the country, there
are 14-15 million TB patients,6 which is nearly one third of the global burden of this
disease. About 3 million of these cases are highly infectious and spread the
disease in the community6.
TB is largely a disease of adults. Within adults, it is prevalent more in older
adults than younger adults and more among males than females7. Although
morbidity and mortality in any age group have significant economic and social
consequences, no community can afford to loose its citizens in prime years of life
since these are not only the productive years in terms of wage earning but also a
period of shouldering family and social responsibilities.
Before 1950, it was widely believed that the problem of TB was only
localised to big cities. The first disease survey carried out by Dr Frimodt Moller in
the villages of Madanapalle district revealed that TB was prevalent in rural areas
also8. The strategic importance of TB control in rural areas of the country was
recognised when the National Sample Survey indicated that 70-80% of TB cases
resided in rural areas since TB was as prevalent in rural areas as in urban areas .
Most of the later surveys carried out in different parts of India have been
conducted in the rural areas. These surveys reveal that TB continues to be as
highly prevalent in these areas as ever before7’16 (Table 1) and that only a small
2
Tuberculosis Among Agricultural Workers And Its Control
proportion of rural population escapes infection through good luck or innate
resistance.
Annually, more than three lakh TB deaths take place in rural areas out of
the total 4.5-lakh TB deaths in the country'7. About 5 to 6% of all deaths in rural
India are contributed by TB17. The age and sex distribution of deaths due to TB in
rural India is given in table-217.
Though TB deaths are more common amongst males, it is pertinent to
mention that TB kills more women than all other infectious diseases and maternal
deaths combinecf6. An analysis of the TB problem among rural women requires
understanding it in an socio-economic context. The rural women are often ignored
in terms of preference and priorities in getting medical facilities. It is only when the
situation worsens and they are unable to take up household activities that they are
brought for the treatment. Women are also disadvantaged in terms of nutritional
status, multiple responsibilities and specific household tasks such as cooking in
the ill-ventilated enclosures. All these conditions make rural women more
conducive to make them fall an easy victim of the disease.
More recently, rural populations have become more mobile and many
migrate to urban areas where they have to live in sub-standard housing
conditions, which is a further risk for developing tuberculosis. Increased rates of
TB have often been observed in migrant population.
In the rural areas of the country, TB is still considered to be a socially
outcaste disease. The patients suffering from the disease often do not disclose it
for a long time. It has partly to do with their lack of knowledge of the symptoms of
the disease and also due to the negative reactions that they fear from the people
around them.
In a study conducted in Pune district, one out of every three TB cases
were found to be engaged as agricultural labourers19. In another study conducted
among farm workers of Uttar Pradesh, one out of every five workers suffered from
some kind of respiratory disease and one-fifth of the respiratory diseases was due
to pulmonary TB20.
The agricultural occupation is associated with an increased risk of TB
because it attracts workers in a high-risk category for TB since most of them have
poor nutritional status and live in poor housing conditions. Farm workers are often
migrant labourers, they are often not in full time employment and are thus in a low
socio-economic stratum. They may also be predominantly male. These
characteristics are all associated with increased risk of TB. Many a time, the
agriculture and farm workers have to work under dusty conditions leading to high
incidence of silicosis among them. Since the patients with silicosis are at a higher
3
Tuberculosis Among Agricultural Workers And Its Control
risk of developing TB21, the agricultural workers specially those exposed to dust
storms comprise a high-risk group for developing TB. Humans usually acquire TB
infection from their immediate environment rather than from an animal source.
However, there is a real risk that agricultural people living in closer contact with
cattle may acquire the infection from them especially when systematic
pasteurization or sterilization of the milk by boiling is not practiced.
In the survey carried out in the central Indian district of Wardha in
Maharashtra, it was found that 42% of the rural population aged 5 years and
above was engaged in agriculture12. About 85% of the working population in rural
areas and 20% in urban areas were engaged in agriculture'2 related activities.
One out of every two chest symptomatics found in the survey was an agricultural
worker since a higher proportion of them (3.1%) had symptoms of cough with
more than 2 weeks duration, chest pain, prolonged fever or history of haemoptysis
compared to 1.9% of the overall population. Even though the prevalence of
sputum positive pulmonary TB among the agricultural workers was not statistically
different from that in the overall population or among other categories of workers,
about half (46%) of the total disease prevalence in the district was contributed by
agricultural workers'2.
On extrapolating the above data nationally, it can be surmised that about
four million agricultural workers suffer from TB at any given point of time, 1.0
million of them are infectious in nature and spread the disease to their family
members, neighbors and co-workers. The time off from work prior to diagnosis
and during treatment is an economic loss to their families and many of the
caregivers also have to take time off from work to assist them. Therefore, the high
prevalence of TB in India has serious and adverse consequences on the
agriculture produce and thus on overall economy of the nation. Also, the deaths of
these workers in the prime of their age have a particularly onerous burden and its
consequences on children and other dependants can be great. Being from lower
socio-economic strata, they are also the people who are least able to cope up with
the disease. Thus the effects of the disease on agricultural families can be
devastating both financially and emotionally.
With the population growth, the absolute number of TB cases in the
country has been on the increase. The advent of HIV epidemic has already
facilitated the return of TB to wealthy nations3. In the developing countries where
the disease was never controlled, the situation is expected to worsen in the future
as a result of the increasing HIV seroprevalence rates since HIV infection is the
single most important risk factor for developing TB3.
A NATIONAL TUBERCULOSIS PROGRAMME (NTP) is being
implemented in the country as an integral part of the general health services since
1962. The programme was evolved by the National Tuberculosis Institute (NTI),
Bangalore after the valuable research studies carried out by it threw light on the
4
Tuberculosis Among Agricultural Workers And Its Control
epidemiological and operational aspects of the programme. Earlier, it had been
established by Tuberculosis Chemotherapy Centre, Chennai that the efficacy of
domicilliary treatment was as good as treating them at the sanatoria. It was
decided that the programme should be felt-need based since a majority of the
patients seek treatment at various health institutions. The objectives of NTP are
as under:
1. To reduce deaths due to TB.
2. To detect as large a number of TB patients as possible and treat them
effectively so that the infectious patients are rendered non-infectious and
active and non-infectious cases do not become infectious.
To achieve the above objectives, following components were considered
necessary:
1. Sputum diagnoses of all cases at the primary health care level.
2. Domiciliary treatment of the detected cases.
3. Provision of basic facilities and basic record keeping at the Peripheral Health
Institutions (PHIs) which include Primary Health Centers (PHCs) and
Community Health Centers (CHCs).
4. Improvised referral services and the access to specialized services for more
complicated cases.
5. Having a District TB Centre (DTC) at each district, which would not only be
responsible for implementing NTP in the district but also provide referral
services to the PHCs and CHCs, which form a part of the health service
delivery system in the rural areas.
The basic organisational unit of NTP is the District TB Programme (DTP).
There are four activities under DTP namely:
(1) Case-finding
(2) Treatment
(3) Management
(4) Recording and reporting.
Case-finding activities in DTP are undertaken
symptomatics attending the various Health Institutions.
by
examining
the
Under the programme, the treatment of sputum positive TB patients has
been accorded priority over that of sputum negative cases in order to cut the chain
of transmission. Treatment is decentralized and is offered on a domiciliary basis.
Anti-TB drugs are issued free and defaulter action is taken in respect of TB
patients who default in the treatment.
Management of DTP covers planning, implementation and maintenance of
various activities under DTP and the responsibility of this rests with the District TB
Officer (DTO) assisted by his key staff.
5
Tuberculosis Among Agricultural Workers And Its Control
The activities under the DTP are co-ordinated through a system of proper
recording and reporting which facilitates rendering the service to the community.
CONSTRAINTS IN TB CONTROL
TB still tops the list of causes of deaths and disease in this country and the
problem in rural areas of the country has not declined from the situation 50
years ago in spite of the advent of anti-TB drugs and implementation of the NTP.
Even the case fatality rates have remained high as shown by the surveys
conducted by NTI before implementing the programme and 20 years after
implementation of the programme22.
One of the most significant obstacles of achieving TB control is the
challenge of implementing TB control activities in rural populations as the health
care infrastructure in most rural areas of the country is still poorly developed.
Accessibility is affected by the factors such as distance to the nearest place where
the patient could go for treatment, which is usually far away in rural areas. It often
takes one full day for the patient to make a single visit especially in view of
general lack of transport facilities. Moreover, poor socio-economic conditions of
the communities make it difficult for the people to travel to far off places at the cost
of losing a day’s wage.
Many of the rural TB patients do not present themselves to medical
facilities in time with the result that there is a delay in diagnosis?3. This delay may
be because of financial barriers that include the cost of transportation and loss of
wages besides the fact that a significant proportion does not feel sick enough to
seek care24. Many of the cases are not even aware of the availability of treatment
in public health services19.
Many a time, the patients on approaching a medical facility are returned
undiagnosed and some incur sizeable expenditure on general antibiotics before
they are diagnosed as TB.
There has been an overemphasis on using X-rays for diagnosing TB,
which leads to overestimation of cases. X-rays, as a case-finding tool has severe
limitations and is about 7-10 times costlier than sputum microscopy, which is also
a more reliable diagnostic tool25.
Inability of the health providers to administer complete and regular
treatment for 6-8 months is a major impediment to controlling TB. Irregular supply
of drugs especially to PHCs, low image of public health services, lack of patient
doctor rapport and high cost of care which include travel cost, loss of wage and
doctor’s fees and cost of drugs when taking treatment from the private sector are
some of the important reasons.
6
Tuberculosis Among Agricultural Workers And Its Control
The rural PHIs lack the administrative and technical support from the DTC
and implement the TB programme in a perfunctory manner. Often, there is
shortage of basic supplies like sputum cups, slides, strain and drugs. Little
attention is paid to patient’s education and there is general lack of accountability
for all categories of health persons.
Under the National Tuberculosis Programme, antitubercular drugs are
provided free of cost to the patients. There is a shortage in the government
pharmacies and the patients have to incur the high cost of procuring drugs at the
market price. Thus, even in a programme offering free service, there are direct
and indirect costs to the patients, which may encourage drug defaulting in the long
run.
Almost half of the patients depend upon public health services for relief24.
However, the services are not satisfactory in many parts of the country with the
result that patients have to seek relief from private health agencies. In addition to
high service charges, these private agencies rely more on X-ray of the chest for
diagnosis and may not adhere to the standard drug regimens?6 leading to financial
losses for the patient and increased possibility of drug resistance. A high
proportion of the TB patients incurs debt being unable to bear the expenses of the
treatment.
The key staff of the DTC seems rather satisfied being engrossed in
providing clinical services and pays little attention to management and supervision
of the programme in the district. Recording and reporting under the programme is
equally bad to give any reliable information on either epidemiology of the disease
or efficiency of the DTP.
In the presence of inefficient case-finding and poor treatment completion
rates, the problem due to the disease continues to be unabated. Less than 50% of
the patients adhere to the complete course of treatment27. When the treatment is
not completed, not only is the patient’s life jeopardized but also the patient
continues to infect others in the community and such infections have a greater
likelihood of becoming multi drug resistant. The cost of treating such patients is so
enormous that it is beyond the scope of any health programme. One of the
alternatives adopted to overcome the problem of drug default has been the
gradual replacement of the 12 month long course treatment with a shorter and
more effective six month short course chemotherapy (SCO), which leads to better
compliance resulting in higher cure rates. Even though SCO has been proven to
be more cost-effective than long course regimen so far it has been introduced only
in 294 districts.
Since the group of agricultural workers is one from lower socio-economic
strata, many a times these workers have to move from one place to another
seeking livelihood. These characteristics pose particular problem for TB control
programme.
7
Tuberculosis Among Agricultural Workers And Its Control
APPROACHES FOR IMPROVEMENT OF TB CONTROL ACTIVITIES
Several innovative approaches would have to be developed to overcome
these problems in implementation of NTP especially for achieving and sustaining
high cure rates for all rural patients with infectious TB.
The importance of prescribing appropriate anti tubercular drug regimens
and preventing treatment default cannot be over-emphasized. Effective TB
treatment not only cures current cases but also prevents future cases, which are
indirect benefits of chemotherapy. One of the major determinants for successfully
treating TB is the level and intensity of supervision by the health care delivery
system. The approach that has been adopted by TB programs all over the world is
to ensure that each dose is administered to the patient under the supervision of a
health worker or a dedicated health volunteer. This strategy is called the Directly
Observed Treatment Short course (DOTS) and has yielded high cure rates28 of
85-90% in many countries and in pilot areas of our country.
DOTS is the only way of ensuring high cure rates and thus has the benefits
of reduction in transmission of infection by rendering infectious cases noninfectious. There are additional savings in future due to lower numbers of relapses
and preventing development of resistance to antibiotics in both of which situations,
treatment is much costlier.
THIS REVISED STRATEGY OF NTP takes advantage of the technology
revolution, which took place by the introduction of DOTS. In countries like
Tanzania, it was shown that DOTS had enhanced the rate of reduction in infectors
(diseased) and infected (potential) by 50% in 15 years29. The revised strategy of
NTP also effectively utilises the enhanced availability of infrastructure and
manpower that has developed in the primary health care system over the years,
but has not been utilised under the NTP.
The objectives of the revised strategy are as under:
1) To cure at least 85% of all newly detected cases of pulmonary TB with
supervised SCO.
2) To detect at least 70% of the estimated incidence of smear positive pulmonary
TB cases. However, efforts at increasing case detection would be made only
after achieving 85% cure rate in the already detected cases.
A chest symptomatic reports to the nearest health facility, where his
sputum is tested. In case sputum examination facility if not available here, then
the patient is referred to the nearest Microscopy Centre. After three sputum
samples have been examined, the patient is put on anti-TB treatment in case at
least two of the three samples are positive. If only one sample is positive, an X-ray
is taken. The medical officer decides the treatment to be given on the basis of Xray and clinical examination. If all the three sputum specimens are negative, then
the patient is given a course of antibiotics for 7-10 days. Incase symptoms still
8
Tuberculosis Among Agricultural Workers And Its Control
persist, then X-ray is taken and the medical officer decides on the subsequent
treatment.
Anti-TB treatment is administered depending upon category of the patient.
During intensive phase, DOTS is administered with the help of a peripheral health
functionary; while in continuation phase a patient collects the drugs on weekly or
fortnightly basis. Drugs are taken 3 times / week throughout.
Drug administration is appropriately recorded on the treatment cards,
which are prepared and kept at the place of diagnosis and treatment. The
information from the treatment card is transferred onto the TB Register, which is
kept at the sub-district level and is updated from time to time by the Senior
Treatment Supervisor (STS). Quarterly reports on case-finding and treatment
outcomes are prepared at the sub-district level and sent to the district level for
compilation and onward submission to State and Central levels. Analysis of data
would take place at district, state and central level and information would flow
back to the sub-districts for corrective actions.
The above strategy should be implemented in all the districts of our
country as early as possible to rapidly cut down the chain of disease transmission.
The government of India has sought World Bank assistance to extend DOTS to
about 330 million people in the course of the next five years to implement this
revised strategy under NTP17. The provision and maintenance of uninterrupted
drug supply of all anti-TB drugs through strengthening of the existing system shall
go a long way in improving compliance and cure rates.
Other suggested inputs needed to intensify TB control efforts are as under.
TB mortality and morbidity would decline only if increased financial support
is made available each year to TB control programmes in developing countries. A
strong political will and advocacy is required to appreciate the enormity of the
problems due to TB and to allocate appropriate budgets for TB control
programmes. Enhanced finances are needed to enable the TB programmes to
undertake training programmes, improve registration systems and monitoring
tools, to finance medicines, microscopes and improve the modest infrastructure so
that these programmes work efficiently. Additional resources are also required to
cater to the increasing number of patients having HIV and TB as these patients
may also require expenses due to hospitalization.
Accurate knowledge and increased awareness among the general public
especially the high risk groups such as agricultural workers needs to be
communicated to remove their misconceptions and modify their help seeking
behaviour favourably. They must be educated that TB is curable with complete
and regular treatment and that sputum microscopy is the most reliable tool for
diagnosing TB. Informing people about the programme must receive the top most
priority. Since a sustained awareness programme can go a long way in more and
9
Tuberculosis Among Agricultural Workers And Its Control
more people reporting for treatment. Community participation in the programme
especially in detection and referral of chest symptomatics for sputum examination
and supervising treatment must be encouraged.
Increased awareness among the people without strengthening the service
delivery would further erode people’s confidence in health services. Diagnosis of
TB, its .treatment and follow-up of patients till they are cured can all be effectively
undertaken at the level of PHC. Therefore, PHCs must be strengthened in respect
of leadership, management, drugs & supplies and record keeping.
Among the health workers, finding more cases is generally considered
more important than ensuring cure of those detected. As a result, defaulter
retrieval under the programme is not undertaken in sincerity. Appraisal training of
health workers in a simple demonstrative manner periodically while covering the
technical and managerial aspects shall help to tackle the problem of non
adherence to treatment effectively.
Strengthening of operation research and improving the functioning of the
existing health care systems, and roping in of NGOs and private practitioners to
assist control programmes are other essential ingredients to successfully combat
the menace of TB.
Improvement in socio-economic conditions of rural populations including
agricultural workers will reduce the burden of the disease as has been observed in
Western countries where the incidence of the disease declined in the beginning of
this century prior to the anti tubercular therapy era.
As TB control programme evolves into the next millenium, the public health
community should take all appropriate actions aimed at intensifying the TB control
efforts in order to reduce the enormous burden imposed by this disease.
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1. World Development Report, 1993: investing in health: The global burden of
disease in 1990, 213, Oxford University Press.
2. Dollin RJ, Raviglione MG & Kochi A: A review of current epidemiological data
and estimation of future TB incidence and mortality; WHO/TB/93. 173.
3. Chadha VK: Global Trends of TB - An epidemiological review; NTI Bulletin,
1997, 33, 11-18.
4. Murray CJI, Styblo K & Rouillon A: TB in developing countries; burden,
intervention and cost; Bull of IUAT & LD, 1990, 65, 2-19.
5. United Nations, 1986: World population prospects, estimation and projections
as assessed in 1984, New York.
6. TB control in India, Developing role of NGOs, ACTION AID India, 1996, 10.
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Tuberculosis Among Agricultural Workers And Its Control
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25.
Indian Council of Medical Research: TB in India - A sample survey, 1955-58,
Special Report Series No.34, ICMR, New Delhi.
Frimodt Moller J, Benjamin P & Mathew P: Results of mass X-ray surveys in
a village population at Madanapalle; Proceedings of the 9,h TB Workers
Conference 1952, 133-43.
Raj Narain, Geser A, Jambunathan MV & Subramanian M: TB prevalence
survey in Tumkur district: Indian J TB 1963, 10, 85-116.
National Tuberculosis Institute, Bangalore: TB in a rural population of south
India - A five year epidemiological study; Bull WHO 1974, 51,473-88.
TB Prevention Trial, Madras: Trial of BCG vaccines in south India for
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ICMR Project Report: Field Trial of short term intermittent chemotherapy
against TB; and ICMR project, Department of Community Medicine &
Development of Microbiology Mahatma Gandhi Institute of Medical Sciences
Savagram Wardha, 1989.
Ray D & Abel R: Incidence of smear positive pulmonary TB from 1981-83 in
rural area under an active health care programme in south India; Tubercle &
Lung Dis 1995, 76, 190-95.
Chakraborty AK, Suryanarayana HV, Krishna Murthy VV & Shashidhara AN:
Prevalence of TB in a rural area by an alternative survey method without
prior radiographic screening of the population; Tubercle & Lung Dis 1995,
76, 20.
Chakma T, Vinay Rao P, Pall S, Kaushal LS, Manjula Datta & Tiwary PS:
Survey of pulmonary TB in a primitive tribe of Madhya Pradesh; Indian J TB
1996,43,85-89.
Gopi PG et al: A TB prevalence survey based on symptoms questioning and
sputum examination; Indian J TB 1997, 44, 171-80.
World Health Organization: The potential economic benefits of the DOTS
strategy against TB in India; WHO/TB/96.218.
Maire Connolly & Paul Nunn: Women & TB; WHO State Qtly 1996, 49/2,
115-19.
Mukund Uplekar, Rangan PS: Tackling TB - the search for solutions; the
foundation for research in a community health; 1996.
Agnihotri MS et al: Disease pattern among farm and construction workers of
Uttar Pradesh - A brief summary; Ind J TB, 1991, 38/2,107.
Narboo T, Angchuk PT, Yahya M, Kamat SR, Pooley FD, Corrin B, Ken IH,
Bruce N, Ball KP; Thorax 1991, “Silicosis in a Himalayan village, role of
environmental dust”.
World Health Organization: “Prevalence and incidence of TB infection and
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Chadha VK & Deshmukh DB: Case-finding and related issues in TB; NTI
Bull, 1995,31,48-53.
Banerji D & Anderson S: A sociological study of awareness of symptoms
among persons with pulmonary TB; Bull of WHO, 1963, 29, 665-683.
Naganathan N, Padmanabha Rao K & Rajalakshmi R: Cost of establishing
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Tuberculosis Among Agricultural Workers And Its Control
26.
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Upleker M & Sheela Rangan: Private doctors and TB control in India: Tubercle and
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WHO/TB/95.183.
Table 1: Prevalence of pulmonary TB in rural parts of India
Sample size
Area & year
Prevalence of pulmonary
TB/1000 population
Bacillary
Abacillary
M-3.2
F-1.5
3.44
(2.29 to 6.11)*
M-5.8
F-3.0
Madanapalle8 (1950)
20,307
(all ages)
National Sample Survey7
(1955-58)
1,22,907
(> 4 years)
Tumkur district. Karnataka9
(1960-61)
21,021
(> 9 years)
4.1
M-5.6
F-2.5
Rural Bangalore10
(4 surveys between 1961-68)
41,000-43,000
(> 4 years)
3.4-4.0
Chingleput (Tamil Nadu)11
(1968-71)
2,06,609
(> 9 years)
10.68
M- 17.04
F - 4.39
Wardha12
(1982-88)________________
North Arcot (Tamil Nadu)13
4,87,654
(> 4 years)
18,688
(> 4 years)
Rural Bangalore14
(1984-86)
21,924
(> 9 years)
16.00
19
M - 25
F- 12
14.29
M-18.86
F - 9.78
1.98
2.41
(by smear alone)
4.4
M-6.4
F-2.3
11,097
Morena district, Madhya
12.7
(> 14 years)
Pradesh15______________
40,000
Raichur district, Karnataka15
10.7
(> 14 years)
(1988-89)
*The prevalence rate varied from place to place in this range.
Table 2: Total TB deaths in rural India by age and sex (000,s)
Age group
0-4
____ 5—14____
15-44
45-59
60 +
Total TB deaths
_____ Rural areas
Females
Males
4.5
1.9
5.3
2.5
85.6
68.8
28.8
76.3
65,1
27.2
234
132
ROHC-WHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999: LN.-6
Ergonomics Practices In Agricultural Processes
P.K.NAG
Deputy Director, National Institute of Occupational Health, Meghani Nagar,
Ahmedabad- 380 016.
Introduction
Application of ergonomics, often referred to as agricultural ergonomics,
emerges as a potential discipline for whole ranging application in farming methods
and practices.
This discipline specifies application of those work sciences
relating human performance to the improvement of work system in farming
activity.
One may perceive the implication of ergonomics based on its
generalized principles, however, there are lacunae for application by following any
defined rule of thumb. Gradual advances in agricultural management, production
and distribution system are indications of transformation of traditional agriculture
to industrial bases. Obviously, wide variations in agriculture suggest that
ergonomics application would certainly differ with the farm practices.
The
countries of Asia and Africa, where the society predominantly depends on
traditional agriculture, have pressing problems of occupational disease and injury
categories due to ergonomics related problems. The exposure to the open field
environment and the strenuous physical jobs are only two of the more obvious
agricultural ergonomics problem. Alleviation of the rigors at the workplace and to
the improvement in performance ability of a person are the ultimate goals and
objectives of ergonomics application.
The attainment of the above objective may only be possible by modifying
the jobs that people do, reorienting and designing the work places and work
spaces, work methods, the tools and the equipment they use and optimizing
human exposure to adverse work environment, whereby it promises reduced
injuries, improved work performance and productivity. This wholistic view has an
implied challenge that the ergonomics should bring about not only the beneficial
changes at the workplace but also a method of assessment of the benefits of
change. Ergonomics has an important role to generate a great deal of information
from traditional farming systems and apply the modem concepts of ergonomics to
improve work conditions and work places. Modern technology is gradually finding
its place in agriculture, with still large-scale dependence on family scale farming.
With the introduction of modern technology, ergonomics becomes essential for its
successful application. The important point here is that the major benefit to the
agriculture is to have safe, healthy and productive worker. Having recognized
that the social costs due to ill health and injuries are real and substantial, it has
been viewed that ergonomics, by helping to provide improvement in farming can
serve as a dominant scientific discipline for socio-technical development. The
philosophy of ergonomic application is generic to the concept of technology
application in any sphere of human activity.
2
Ergonomics Practices In Agricultural Processes
Areas Of Ergonomics Application
The practitioners in ergonomics are face to face with stark realities, that is:
when, where and how to use ergonomics? That means, ergonomics is important
and useful in those work situations when people are present, such as when
people operate production systems, when people repair and service equipment
and the like. Typically, the application of ergonomics has been largely practiced in
the correction and prevention of problems in agriculture.
The considerations
include the study of human needs, characteristics, abilities and skills as applied to
design, production, management, maintenance and in some cases recycling and
destruction of high quality and human products or services with a given
physical/chemical environment and social surroundings.
Agricultural methods
and practices vary across national boundaries:
•
o
Industrial agriculture - industrialized countries of the West (temperate climate)
and specialized sectors of the tropical Countries.
Green revolution agriculture-well endowed areas in the tropics, primarily
irrigated plains and deltas of Asia, Latin America and North Africa.
Resource - poor agriculture - hinterlands, dry lands, forests mountains and
hills, near deserts and swamps. About one billion people in Asia, 300 million
in sub Saharan Africa and 100 million in Latin America are dependent on this
form of agriculture.
With distinct agro-climatic features, the farm crops are grouped as follows:
•
•
•
o
•
•
Field crops (cereals, oil seeds, fiber, sugar and fodder crops) are rain fed or
cultivated through controlled irrigation.
Upland and semi upland cultivation (wheat, groundnuts, cotton and so on) are
practiced where irrigation or rainwater is not abundantly available.
Wet land cultivation (rice crops) is practiced where the land is ploughed and
puddle with 5-6 cms. Of standing water and seedlings are transplanted.
Horticulture crops are fruit, vegetable and flower crops.
Plantation or perennial crops include coconut, rubber, coffee, tea and so on.
Pastures are anything nature grows without human intervention.
Farming Operations, Hand Tools And Machinery
Farming in India is labor intensive and estimated that human effort
provides more than 70% of the energy required for crop production tasks.
Improvement in the existing tools, equipment and methods of work has significant
effect in minimizing human strain and fatigue and increasing farm productivity.
For field crops, farm activities may be categorized as below:
3
Ergonomics Practices In Agricultural Processes
•
Seedbed preparation - A suitable seedbed is one that is mellow yet compact
and free from vegetation that would interfere with seeding.
Seed-bed
preparation involves use of different types of hand tools, shallow chisel, Desi
or mould board plough pulled by draft animals or tractor implements for
blowing, harrowing and so on. About 0.4 hectare (ha) of land can be tilled by
a bullock-drawn plough in a day, and a pair of bullocks can provide power to
the extent of 1 horse power (hp).
•
Sowing, planting and fertilizer application - The sowing of seeds and
planting of seedlings involve the use of planters, seeders, drills and the
manual broadcasting of seeds. About 8% of total person hours are required
for broadcasting of seeds and uprooting and transplanting of seedlings, in the
broadcasting of seeds/fertilizer by hand, manually operated broadcasters allow
uniform distribution with minimum drudgery.
Seeding behind a plough
consists of sowing of seeds in a furrow opened by a wooden plough. In
drilling, seeds are placed in the soil by a seed drill or seed cum fertilized drill.
About 1 /3rd of the world’s rice is grown by the transplanting system. This is
also done for tobacco and some vegetable crops. Usually, germinating seeds
are broadcasters densely on a puddle field. The seedlings are uprooted and
transplanted to a puddle field by hand or with manual or power operated
transplanters.
o
Plant protection - Fertilizer, pesticides, herbicide and other chemical
applicators are operated by pressure through nozzles or by centrifugal force.
Large scale spraying is based on the hydraulic nozzle, spray atomizer, either
manually operated or using tractor-mounted equipment. Knapsack sprayers
are scaled down models of vehicle mounted sprayers. A compression
knapsack sprayer consists of a tank, a pump and a rod with nozzle and hose.
A lever operated knapsack sprayer (10-20 I) has an operating lever. A power
knapsack sprayer consists of a chemical tank of about 10-1 capacity and an
air-cooled engine of 1-3 hp. The sprayer and engine unit is mounted on a
frame and carried on the operator’s back. A hand operated bucket sprayer
and foot-operated sprayer require 2 persons for operating the pump and
spraying. When carried on the shoulder for prolonged periods, the vibrations
of knapsack sprayers/chemical applicators have detrimental effects on the
human body. Spraying using knapsack sprayer results in potential skin
exposure (the leg experience 61% of the total contamination, the hands 33%,
the torso 3%, the head 2% and the arm 1 -%).
o
Irrigation - Irrigation is a prerequisite for intensive cropping in arid and semiarid regions. Since time immemorial, various indigenous devices have been
used for lifting water. Lifting water by different manual methods is physically
strenuous. In spite of the availability of water pump sets (electrical or engine
powered), manually operated devices are widely used (e.g. swing baskets,
counter poise water lifts, water wheels, chain and washer pumps,
reciprocating pumps). Particularly, the swing basket is often used for lifting
4
Ergonomics Practices In Agricultural Processes
water from an irrigation channel and the work demands heavy physical activity
with adoption of awkward body movements and posture.
•
Weeding and inter-cultivation - Undesirable plants and weeds cause losses
by impairing crop yields and quality, harboring plant pests and increasing
irrigation costs. Reduction in yield varies from 10-60% depending upon the
thickness of growth and the kind of weeds. About 15% of human labor are
spent in removing weeds during the cultivating season. Women typically
comprise a large portion of the workforce engaged in weeding. In a typical
situation, a worker spends about 190-220 hours weeding one hectare of land
by hand or hand hoe. Of several methods (e.g. mechanical, chemical,
biological, cultural), mechanical weeding, either by pulling out the weeds by
hand or with hand tools like the hand hoe and simple weeders, is useful in
both dry and wet land.
Harvesting - In rice and wheat crops, harvesting requires 8-10% of the total
person hours used in crop production.
Despite rapid mechanization in
harvesting, large-scale dependence on manual methods will continue for years
to come. Hand tools (sickle, scythe and so on) are used in manual harvesting.
The scythe is commonly used in some parts of the world, because of its large
area of coverage. However, it requires more energy than harvesting with a
sickle. Harvesting accidents, lacerations and incised wounds are common in
paddy, wheat and cane sugar fields. The hand tools are primarily designed for
right handed persons, but are often used by left-handed users who are
unaware of the possible safety implications.
o
Threshing - Threshing includes separation of grains from the earheads. Age
old manual methods of threshing of grain from the paddy pinnacle are: rubbing
the earheads with one's feet, beating of the harvested crop on a Plank, animal
treading and so on. In manual threshing by beating one separates about 1.6 1.8 kg of grain and 1.8 - 2.1 kg of straw per minute from medium sized
paddy/wheat plants. Mechanical threshers carry out threshing and winnowing
operations simultaneously. The pedal threshers (oscillating or rotary mode)
increases the out put to 2.3 -2.6 kg of grain (paddy/wheat) and 3.1-3.6 kg of
straw per min. Pedal threshing is a more strenuous activity than manual
threshing by beating. Power threshers are gradually being introduced in green
revolution areas. Essentially they consist of a prime mover, a threshing unit, a
winnowing unit, a feeding unit and an outlet for clean grain. Self-propelled
combines are a combination of a harvester and a thresher unit for grain crops.
Fatal accidents have been reported in grain threshing using power threshers
and fodder cutters. The rotor can injure hands and feet. The position of the
feeding chute can result in awkward postures when feeding the crop into the
thresher. The belt powering the thresher is also a common cause of injuries.
With fodder cutters, the operators can sustain injury while feeding the fodder
into the moving blades. Children sustain injury when playing with the
machines.
5
Ergonomics Practices In Agricultural Processes
•
Winnowing - Winnowing is a process to separate grains from chaff by blowing
air, using a hand fan or pedal - or motor driven fan. In manual methods the
whole content is thrown up in the air, and the grain and chaff get separated out
by differential momentum. A mechanical winnower may, with considerable
human exertion, be hand or pedal operated. Other post harvest operations
include cleaning and grading of grains, shelling, decorticating, hulling, peeling,
and slicing, fiber extraction and so on.
•
Manual material handling tasks - Most agricultural activities involve manual
material handling tasks (e.g. lifting, lowering, pulling, pushing and carrying of
heavy loads), resulting in musculoskeltal strains, falls, spinal injuries and so
on. The fall injury rate increases dramatically when the fall height is more than
2 meters; impact forces are reduced many fold if the victim falls on soft earth,
hay or sand. In rural areas, loads weighing 50-100 kg. might be carried
several miles on a daily basis. In some Countries, women and children have
to fetch water in large quantities from a distance. These arduous tasks need
to be minimized to the extent possible. Different modes of load carrying
involve carrying on the head, on the hips, on the back and on the shoulder and
these have been associated with a variety of bio-mechanical and spinal
disorders. In general, optimization of loads that may be lifted or carried would
help in minimizing the arduous tasks and its associated risk potentials.
In view of the diversity of farm activities, certain organizational measures
towards redesigning of tools and machinery, methods of work, installation of
safety guards on machinery, optimization of human exposure to adverse work
environment and so on may significantly improve conditions of work for farming
populations. Extensive ergonomic research on farm methods and practices, tools
and equipment may generate a great deal of knowledge for the betterment of
health, safety and productivity of billions of agricultural workers. This being the
world’s largest industry, the primitive image of the sector, particularly the resource
poor tropical agriculture, could be transformed as task oriented. Thus rural
workers can undergo systematic training on the hazards of jobs and safe
operational procedures can be developed. The safety education at all levels are
important, whereby the workers undergo the procedure of systematic learning and
hazards of jobs and safe operational procedures are outlined. The success of
injury prevention lies in each adult and child knowing the hazards on the farm and
doing his best to prevent these accidents.
ROHC-WHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999: LN.-7
Pesticide Residues in Food Chain and Their Implications
M.D.AWASTHI
Pesticide Residue Laboratory, Indian
Hesarghatta, Bangalore - 560 089.
Institute
of
Horticultural
Research,
Production of food crops in field and subsequent storage suffer heavy
losses due to pest infestation more so in tropical countries due to
perpetuation of a number of insects and diseases.
These losses are
quantitative as well as qualitative and account to the tune of Rs.6000.00 crores
annually in India (Table 1). Pesticide Chemicals have decidedly been proved
to control these losses effectively. However, pesticide consumption in India
is still low as compared to developed countries (Table 2). This is mainly due
to the importance of their use has not reached to common farmer. Further,
these chemicals are costly too. Therefore, only progressive farmers are
currently using pesticides under irrigated conditions of crop production. Apart
from agriculture use the pesticide use in health program for control of vectors of
various diseases has also achieved significance. Among the various pesticides
used in the country, insecticides constitute 75%, fungicides 15%, weedicides
6% and others 4%. To date, 144 chemicals are registered with Government of
India that come under the category of pesticides possessing insecticidal,
fungicidal, nematicidal, weedicidal and molluscicidal properties.
Pesticides being toxic in nature, leave behind their residues when used
for pest control. Further their indiscriminate use is creating pesticide pollution
of environment in addition to contaminate the food chain as well as non targeted
living organisms without much considerations on the implications of possible toxic
hazards. The progressive increase in pesticide usage in different crops in India
(Table 3), therefore, suggest periodic monitoring of pesticide contamination
levels in food chain. The magnitude of pesticide pollution and contamination in
food chain comprising of food grains, vegetables, fruits, spices, animal products,
air and water in India have been evaluated periodically by various research
workers.
Pesticide Residues in food grains and pulses
The food grains of wheat, rice, jowar and pulses e.g.,arhar, mung and
gram were found to be loaded with residues of pesticides like DDT, HCH,
heptachlor, aldrin and malathion across the country from time to time. The
contamination of food grains of wheat, rice and jowar were found in the range
of 37.9 to 58.1%, rice grains showing highest contamination. The contamination
of pesticide residues in samples of pulses was equally high ranging between
35.9 to 52.94% mainly in arhar, mung and gram.
Arhar samples showed
highest contamination levels.
2
Pesticide Residues in Food Chain and Their Implications
The wide spread and higher level of pesticides contamination in
grains is mainly due to pesticide use during storage.
Table 1: Losses due to various pests
Category of pests
Percent Loss
Monetary value in Rs.(crores)
1980
1560
1200
420
480
33
26
20
7
8
Weeds
Plant diseases
Insect Pests
Rodents
Miscellaneous
Source: Sachan (1989). Pesticides in Agriculture. Indian Farmers Digest, 22: 9-13
Table 2: Consumption of pesticides in different Countries
Country
Pesticide consumption (g/ha)
10,790
1,870
1,490
336
127
Japan
Europe
U.S.A.
India
Africa
Source: Sachan (1989). Pesticides in Agriculture. Indian Farmers Digest, 22:9-13.
Table 3: Use of pesticides on different crops in India
% pesticide share
% cropped Area
Cotton
Rice
Fruits & Vegetables
Plantation
Cereals, Millets, Oil Seeds
52-55
Sugarcane
Others
2- 3
5
24
3
2
58
2
6
Crops
1.
2.
3.
4.
5.
6.
7.
17-18
13-14
7- 8
6- 7
1 - 3
Source: Sachan (1989). Pesticides in Agriculture. Indian Farmers Digest, 22:9-13.
food
3
Pesticide Residues in Food Chain and Their Implications
Table 4: Status of Pesticide Residues in Market samples of food
Status of Residues
Above tolerance level
Within tolerance level
Not detectable
Percentage of Samples
World
India
1.20
18.19
80.00
25.0
72.5
2.5
Source: Kalra, R.L., Pesticide Residues in Food in India - An Overview, P.A.U. and
Ludhiana.
Pesticide Residues in Vegetables
It is of common knowledge that vegetable production involves heavy
pesticide use during fruiting and there is very little gap between the pesticide
application and harvest. Therefore, wide spread contamination of pesticide
residues was observed in most of the vegetable samples.
Leafy vegetables
have shown highest contamination in cent per cent samples while significantly
higher level of contamination was reported in potato and starchy vegetables
(57.8 to 76.7%); cauliflower (56.0%); tomato (44.4%); cabbage (32.0%); bhindi
(57.1%) and brinjal (57.1%) from different places. Among the various pesticides
being used, DDT, HOH, Lindane, heptachlor, aldrin, dieldrin were the main
contaminants found persisting.
Pesticide Residues in Fruits
Like vegetables, fruit cultivation to economic production is not possible
without effective pest control. Accordingly, heavy pesticide applications are
done throughout cropping season resulting in persistence of their residues at
harvest also. The monitoring of samples of different fruits from across the country
has shown variable pattern of contamination in the range of 24.1 to 100%.
Percent contamination in mango fruit samples ranged between 24.1 to 95%
while other fruits recorded variable contamination to the extent of 56.6%
grapes, 21.0 to 84.6% guava, 23.8% sapota; 85.7% banana; 90.0% apple;
100% plum and 90.9% sweet lemon.
Like vegetable contamination organo
chlorine pesticides were main contaminants in fruits.
Pesticide Residues in Oil Seeds and Oils
Moderate to very high level of pesticides contamination was recorded in
samples of various oil seeds and oils. Accordingly, 56.2% groundnut seeds;
79.5% cotton seeds; 81.8% castor seeds; 40% sesame seeds; 39.3% sunflower
seeds and 37.1% safflower seeds were found contaminated with various
pesticides. Oil samples were by and large, contained higher and wide spread
pesticide residues. A very high contamination was reported in oils of mustard
4
Pesticide Residues in Food Chain and Their Implications
(93.3%); coconut (100%), groundnut (70.5%), sesame (100%), against safflower
(53.8%); vegetable fats (58.7%) and sunflower (12.8%).
Oil seeds and oils in general were contaminated with DDT and HCH
residues only.
Pesticide Residues In Animal Products
Animal products as food consisting of milk and milk products, meat, fish
and egg samples have also shown wide spread pesticide contamination. Meat
found
samples
of goat, sheep, cow/buffalo, pork and
chicken
were
70.4%
contaminated
at the level of 57.9, 100.0, 41.2, 100.0 and
hard to
respectively as against 66.3% fish and 72.5% egg samples with
degrade organochlorine pesticides.
Bovine milk registered high contamination at the range of 64.6 to
91.6%. Milk products like ghee and butter have been found to show 100%
contamination. It is alarming to note that 49.8% human milk have also shown
pesticide residue contamination.
Pesticide Residues In Spices
The monitoring of spice samples of black pepper, celery seed, dill seed,
fennel, ginger and turmeric have shown 100% contamination with pesticide
residues of DDT and HCH.
Pesticide Residues In Water
Traces of organochlorine and organophosphate pesticide residues in
well, pond and river water have also been reported. The persistence of
pesticide residues in drinking water is mainly due to movement of pesticide
residues from the site of application. The soil being the final sink of pesticides,
whatever way they are being used further transport the residues to water sources.
The magnitude of pesticide contamination of food chain in India can be
summarized through the results of a study by FAO, 1984 that all the 1500
samples of cereals, pulses, milk, oil and meat sampled from all over India
contained DDT and HCH residues and these residues exceeded the WHO safety
limit in 25% samples. In contrast only 1.2% of food samples had residues above
tolerance levels in market basket surveys in developed countries (Table 4).
Further more, Indian babies imbibe higher quantities of DDT from their mother's
milk than American, Swedish and German babies. More recently, a coordinated
monitoring study at various centers of All India Co-ordinated Research Project
on Pesticide Residues (ICAR) across the country have also established wide
spread contamination of food grains, fruits, vegetables, milk, milk products,
5
Pesticide Residues in Food Chain and Their Implications
fishes, meat and animal feed particularly with hard to degrade pesticides like
DDT and HCH.
In addition to the adverse effects on human health, pesticides have also
polluted water, soil and air mainly due to indiscriminate and injudicious uses.
This has therefore led to problems like environmental pollution, bio-magnification
of terminal residues, build up of insecticide resistance, destruction of natural
enemies of insect pests, resurgence of other species of insects, poisoning of
non-targeted organisms like birds, fishes, earthworms etc.
Causes Of Pesticide Residue In Food
In India, maximum exposure of pesticides to consumers has been through
vegetables and animal products such as milk, milk products, meat, fish etc. The
high residue content in vegetables can be attributed to the frequent pesticide
applications and non-compliance of recommended waiting periods. A high
residue found in animal product can be attributed mainly to feeding of animals
with contaminated feed and fodder with persistent types of pesticides like DDT,
HCH etc, which accumulate in body. Surprisingly, at times, far excessive
residues have been reported in vegetables and grain samples than obtained
even immediately after spraying. In vegetables, this could be attributed to
malpractices like dipping of vegetables in pesticide solution for enhancing
keeping quality or better appearance. Sometimes, higher doses are used
inadvertently, in absence of measuring devices or proper applicator.
Further, the pesticide residue problem in food is more complicated
because of the bulk use of organochlorine compounds like DDT & HCH. These
are major pollutants and virtually detected everywhere ■ in crop plants, soil,
water and animal system including man. Inspite of the extremely low level of
pesticides consumption in India, observed residues above the prescribed
maximum residue limit are substantially higher than
the situation in
developed countries.
These are several causes for persistence of pesticide residues in food.
The use of BHC in agriculture and uses of DDT in public health programmes
are the major contributors to this problem.
Other
pesticides like,
organophosphorus, carbamates and synthetic pyrethroids and even
some
chlorinated pesticides like aldrin, dieldrin, chlordane, heptachlor, lindane,
endosulfan etc., contribute very marginally to residue problem. Basically either
the residue is small and specific or the product degrades quickly enough to
leave limited residues. However, these are specific situations that result in the
build up of pesticide residues in food chain.
1.
Excessive and over dose applications at farmer’s end
6
Pesticide Residues in Food Chain and Their Implications
the
scientific
2.
Improper
use of
recommendations
3.
Not following the minimum waiting periods prescribed between
pesticide application and harvest
4.
Direct mixing of pesticides with grains during storage.
5.
Injudicious use of pesticides in and around dairies, vegetable and
fruit yards, slaughter houses, fish ponds, flood processing units
for control of pests like house flies, cockroaches and carry over
infestations.
6.
Faulty pesticide residue analysis.
pesticides
not
following
Toxicity Hazards Due To Pesticide Residues And Safety Measures
The toxicity due to pesticides residues, apart from acute effects,
produces latent diseases and disorders such as cancer, heart diseases, brain,
kidney and lever damage as well as sterility, spontaneous abortions and birth
defects. Indians face a much higher risk of above effects as they carry higher
quantities of pesticide residues in their body than people in developed
countries. The risk from acute or sub-acute toxicity is unlikely to be concern in
case of consumers as they seldom come in contact with pesticides directly.
The consumer is mainly exposed to pesticides through consumption of
contaminated food with toxic pesticide residues.
The Government through
legislation has enforced many safety factors to ensue that pesticide residues
remain below the prescribed maximum residue limit (MRL). These include rate
of pesticide application, time of application, number of application and duration
between the last application and harvest, commonly called waiting periods.
It is all the more necessary to keep a constant watch on the extent of
pesticide contamination of food chain. Therefore, a regular and periodic
monitoring of food commodities for the persistence of pesticide residues is carried
out and public are cautioned to the possible hazards. In such a case, it will be
highly useful to decontaminate the food commodities before consumption at
domestic levels through the processes like washing with water, washing with
dilute detergent solution, peeling off the fruit skin etc., that can dislodge
substantial pesticide residues absorbed over food grains, fruits and vegetables.
Further keeping in view the environmental pollution and the adverse effects due
to excessive residues following repeated and indiscriminate use of pesticides,
the idea of Integrated Pest Management (IPM) was mooted. IPM programs
depend on multi component suppression of pest population and restrict the
regular prophylactic usage of broad-spectrum pesticides. Therefore, the main
component of IPM is not only pest management but also pesticide residue
management by reducing pesticide load in order to protect the environment
and life from the possible hazards due to toxic pesticide residue.
ROHC-WHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999: LN.-8
Pesticides Related Health Problems
DR. (MRS.) SANDHYA KULSRESTHA
Joint Director (Med. Pharm.), Directorate of Plant Protection, Quarantine
and Storage, N.H. IV, Faridabad, (Haryana)
The need of pesticides is well established for protecting the crops from
insect pests in agriculture and human health from vector home diseases in public
health programmes. A wide range of insecticides, fungicides, molluscicides,
bactericides and herbicides including fumigants are being used in agriculture.
In public health programmes pesticides are used to control malaria, filaria,
onchrocerciasis, schistosomiasis and trypansomaiasis. As pesticides are
inherently toxic to living organisms, they are likely to affect the health of human
beings. Concerns about the effects of pesticides on human health have been
voiced in a number of reports. The population may be exposed to pesticides in
different ways and different degrees. The exposure may be intentional (suicidal,
homicidal) or unintentional (occupational or accidental or residues). Only a
proportion of population is likely to receive a pesticide dose high enough to
cause acute severe effects while approximate size of the population at risk to
long term, low level of exposure to pesticides is very high.
Presently about 150 pesticides are registered for use in our country.
These are of varied chemical nature and have great difference in their mode
of action, uptake by the body, metabolism and toxicity to human beings.
Pesticides which have a high acute toxicity but are readily metabolized are
eliminated, their main hazard in connection with acute, short-term exposures.
However, with those pesticides, which have a lower acute toxicity but a strong
tendency to accumulate in the body, the main hazard is in connection with long
term exposure. Acute effects are usually easily recognized whereas effects of
long term exposures to low doses (viz. pesticide residues in food) are often
difficult to distinguish.
Adverse effects due to pesticides are caused not only by active
ingredients and associated impurities but also by solvents, carriers, emulsifiers
and other constituents of the formulated product. The severity of adverse
effects of exposure to pesticides depends on the :
dose; for most pesticides, a dose effect relationship has been defined.
the route of exposure. It may be oral, dermal or inhalation.
2
Pesticides Related Health Problems
its absorption in the body: fat-soluble pesticides are better absorbed
through intact, skin than water-soluble pests. The absorption is more
from the wet skin and from certain sites like eyes and lips or through
abraded skin. High temperature and humidity of the environment
facilitates the absorption. The vapors of pesticides or aerosol droplets
smaller than 5 ^m in diameter are absorbed through the lungs.
type / nature of its effect: Headache, giddiness, vomiting, salivation,
lacrymation,
convulsions,
allergic
reaction,
cardiac
or
respiratory/irregularities etc.
its accumulation and persistence in the body
health status of the individual: Malnutrition or dehydration
increase sensitivity to pesticides.
is likely to
The sign and symptoms of acute poisoning of some group of
pesticides are characteristic viz. organophsophorous and carbamate group of
pesticides has anticholinesterase activity and therefore exhibit the sign and
symptoms of cholinesterase inhibition which include diarrhea, lacrymation,
salivation, flushing, miosis,
increase in
blood
pressure, pulse rate,
breathlessness, palpitation and in severe cases cardioarrythmias, convulsions
and respiratory distress. In cases of organochlorine pesticides (DDT, BHC,
endosulfan) which act by altering the transport of Na+ and K+ across axonol
membranes, thus causing an increased negative after potential, prolonged
action potentials and repetitive firing after a single stimulus, the sign and
symptoms of poisoning with high doses which paresthias of tongue, lips and face,
apprehension, hypersusceptibility to stimuli, irritability, dizziness, tremor and
tonic and clonic convulsions.
Synthetic pyrethroids (allethrin, parallethrin,
deltamethrin, cyfluthrin etc.) have
generally
low acute toxicity
and
therefore considered comparatively safe. Their low acute toxicity is due to their
rapid bio-transformation by ester hydrolysis and/or hydroxylation. However, many
of these pyrethroids may cause allergic reaction or contact dermatitis.
Rodenticide warfarin and bromodiolone act by inhibiting the synthesis of vit. K by
liver and therefore interfere with normal clotting mechanism of blood resulting in
bleeding from various sites viz. petechiae, malena, haematomesis, haematuria
etc. Other group of pesticides may exhibit non-specific sign and symptoms viz.
headache, giddiness, nausea, vomiting, tremors, breathlessness etc. on acute
exposure.
3
Pesticides Related Health Problems
The chronic effects or effects of long term exposure to pesticides include:
Neurological effects :
1.
a)
b)
c)
d)
2.
Delayed neurotoxicity : Certain OP compounds eg. leptophos
Behavioural changes: Certain OP compounds
Lesions of CNS: OP, OC and organomercurials
Peripheral neuritis: Chlorophenary herbicides, pyrethroids and
certain OP compounds
Reproductive effects:
a)
b)
c)
Sterility in males : Dibromochloropropane (DBCP)
Effect on female reproductive system of animals : Chlorodecon, thiram
and ziram.
Teratogenicity and fetal toxicity in some animal species: Captan, carbaryl,
folpet, organomercurials, benomyl etc.
Pesticides included teratogenicity in animal experiments were usually
dose-dependent and the doses required to produce teratogenic effects were
much higher than those that of human beings might be expected to receive
under normal conditions.
3.
Bone marrow effects:
Aplastic anemia:
blood dyscrasias
4.
Cancer:
International
Agency
for
Research
on
Cancer (IARC)
has evaluated the potential carcinogenicity of a number of pesticides.
Ethylene dibromide and ethylene oxide are classified as "probably
carcinogenic to human beings" while some other pesticides like DDT,
BMC, Chlorophenols, Chlorophenoxy herbicides etc. are classified as
"possibly carcinogenic to human beings".
5. Skin effects:
Contact dermatitis
Allergic sensitization
6.
Due to idosyncratic bone marrow reactions.
DDT, Captafol lindane, malathion, benomyl, paraquat,
Zineb
Effect on immune system:
Dicofol, trichlorfen and chlorinated pesticides. An increase in IgG and
decrease in IgM and C-3 complement levels were seen in 51 exposed
workers of chlorinated pesticides.
4
Pesticides Related Health Problems
7. Cataract formation:
By diaquat.
8. Optic nerve atrophy:
Methyl bromide OP compounds
9. Cellular proliferation:
Paraquat
Very limited epidemiological data are available for evaluation of health
effects of pesticides on humans. Epidemiological studies of low dose group are
difficult, because, the chronic effects are often not specifically associated with
pesticide exposure and the exposure or dose levels are often difficult to
measure. In addition, the effects take long time to develop in low-dose groups.
In developing countries like India with commercial agriculture, the
benefits of the pesticides are better understood than their hazards or adverse
effects and many times the farmers are unfamiliar with the associated risks and
necessary safety measures. Further, in developing countries the proportion of
population dependent
on agriculture is generally high, therefore, even if
pesticide use is low, relatively more people are involved in the handling of
pesticides, or live in areas where pesticides are used in agriculture. Therefore, to
minimize the pesticide related health effects, emphasis is required to be placed
on the occupational health of the workers in agricultural sector with appropriate
medical surveillance. The scope of health problems related to pesticides in the
agricultural sector should be defined through appropriate surveys to determine:
a) The types and amount of pesticide used
b) The number, age and sex of the workers exposed.
The medical practitioners should be emphasized about the need to
integrate occupational health with public health programmes. A system of
priorities should be established, to ensure that available resources are used to
solve these problems which are critical and pressing.
References
1.
Wayland J Hayes, Jr. (1975) Toxicology of pesticides: Williams & Wilkins
Co., Baltimore, USA.
2.
T.B. Hart (1989) Pesticide use - risks or safety? Recent advances in
clincial Pharmacology and Toxicology, 4,197-218.
3.
WHO (1990) Public Health impact of pesticides used in agriculture.
4.
Nonmetallic Environmental Toxicants: Air pollutants, Solvents, Vapors
and Pesticides. In: The Goodman & Gilman's Pharmacological Basis of
Therapeutics, 9th Ed., 1996.
ROHC-WHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999: LN.-9
Pesticides And Human Health
DR. D. P. NAG
Officer-In-Charge, Regional Occupational Health Centre (Southern), I.C.M.R., Library
and Information Centre, Bangalore Medical College Campus, Bangalore -560 002.
DO WE NEED PESTICIDES?
For nearly half a century agrochemicals have been a boon to man-kind. They
have helped to grow more food, over-come crop pests and diseases and even control
the scourges like malaria and plague.
In our country, insect pests alone cause serious losses to many of the crops.
In 1993, it was estimated that there were losses of Rs.600 crores in Gujarat, Rs.300
crores in Haryana, Rs.50 crores in Andhra Pradesh, Rs.193 crores in Karnataka,
Rs.153 crores in Kerala, Rs.116 crores West Bengal and Rs.153 crores in Bihar.
Acording to another study made by the Director of Ecology, Punjab Agricultural
University, Ludhiana,during 1983, the total estimated losses to crops in India for want
of suitable control of field pests come to Rs.3,274.5 crores in 1976 and Rs.5181.2
crores in 1983. These figures, however, also include the grain losses in storage.
Likewise, the losses caused by weeds to major crops in India, have been estimated to
be approximately Rs.420 crores per annum. The percent reduction to yield of
important crops due to weeds is reported to be 16 in wheat, 41.6 in rice, 39.8 in
maize, 33.8 in groundnut, 47.5 in cotton and 34.2 in sugarcane. Especially, crops like
pulses, mustard and cotton cannot be grown profitably without pest control and use of
pesticides.
Pesticides are, therefore, essential to meet the increased food production and
in the control of public health programmes.
ARE PESTICIDES HAZARDOUS?
All pesticides are inherently poisonous and have injurious effects on living
organism including man and domestic animals. They may cause very simple skin
irritation to premature birth or cancer in experimental animals or man. In addition,
they may contaminate the soil, water and the environment. They also leave traces
(residues) in food which reach the man and domestic animals. Besides, they may
also have effects on non-target organisms in the environment.
2
Pesticides And Human Health
DO YOU KNOW THE LEGAL CONTROLS ON PESTICIDES?
Two important Central legislations concerned with pesticides are:
The Insecticides Act, 1968 and the Insecticides Rules, 1971, framed under the
said Act.
The Prevention of Food Adulteration Act, 1954 and the Prevention of Food
Adulteration Rules, 1955, framed under the said Act.
The tolerance limits for the residues of pesticides in food or food commodities,
are prescribed under this Act. These limits are prescribed based upon the life
time data on laboratory animals including chronic toxicity studies.
WHAT IS TOXICITY OF A PESTICIDE?
The injurious effects produced by pesticides are known as toxic effects. The
toxicity of a pesticide is the inherent ability of the chemical to cause damage. The
hazard, whereas is the possibility of the compound to cause injury. To illustrate
sodium cyanide and hydrogen cyanide have the same toxicity but hydrogen cyanide
is more hazardous as it is in the gaseous form when compared to sodium cyanide
which is in the form of solid.
WHAT ARE DANGERS AND HOW TO ASSESS THE SAFETY OF A PESTICIDE?
A vital question to be answered about any new toxic pesticide is: Does it
present dangers to those who will use it? The dangers produced may be immediate
or delayed. To assess the acute and delayed effects of a pesticide a series of
toxicological tests are carried out on laboratory animals known as short term and long
term studies to know all the possible problems from skin irritation to premature birth,
cancer etc. Based on the scientific data so generated extrapolation of the possible
effects to man, is made. This type of extrapolation of laboratory experimental data to
human beings may not be fool proof as there is no animal species that has similar
bio-chemical metabolic path ways in man. Another important factor in the evaluation
of the toxicological studies is that toxic response of a chemical is species and also
route dependant in addition to dose-dependence. However, all the necessary tests
are carried out using suitable experimental animals and the data so generated are
considered before granting registration for pesticides in the country.
3
Pesticides And Human Health
If on scrutiny it is found that the chemical is phytotoxic, non-effective on the
target organism or residues in the treated crops/commodities are above the tolerance
limits prescribed under the Prevention of Food Adulteration Act, 1954, or toxic to
human beings or animals, the product is denied registration under the Insecticides
Act.
FEW BASIC CONCEPTS CONCERNED WITH TOXICITY
Insecticide - Within the meaning of the Insecticides Act, 1968, an insecticide
means any substance specified in the schedule or to be included in the schedule or
any preparation containing any one or more of such substances, if such substance or
preparation is intended for the purpose of prevention, destroying, repelling or
mitigating any insects, fungi, weeds, rodents or other forms of plant or animal life not
useful to human beings.
Toxicity - is the property of a substance that causes any adverse effects in
an organism.
Acute toxicity - is the property of a substance that causes adverse effects in
an organism through a single short term exposure.
Subacute toxicity - is the property of a substance that causes adverse
effects in an organism upon repeated or continuous exposure within less than half the
lifetime of that organism.
Chronic toxicity - is the property of a substance that causes adverse effects
in an organism upon repeated or continuous exposure over a period of at least half
the lifetime of that organisms.
A mutagenic - substance can induce changes in the genetic complement of
either somatic or germinal tissue in subsequent generations.
A tetragenic - substance can produce or induce functional deviations or
developmental anomalies, not heritable, in an animal embryo or fetus.
A oncogenic - substance can produce or induce either benign or malignant
tumor formations in living animals.
Acute oral LD 50 - is the single orally administered dose of a substance,
expressed as milligrams per kilogram or body weight, that is lethal to 50 percent of
the test population of animals. Note that the LD 50 is specific for each experimental
animal and for each route of administration to the animal (e.g., oral, dermal,
inhalation, etc.).
4
Pesticides And Human Health
Acute dermal LD 50 - is a single dermal dose of a substance, expressed as
milligrams pe kilogram of body weight, that is lethal to 50 percent of the test
population of animals under test conditions.
Acute LC 50 - is the concentration of a substance, expressed as parts per
million parts of a medium, that is lethal to 50 percent of the test population of animals
under specified test conditions.
Pesticide Residue - means any substance or substances in food for man or
animals resulting from the use of a pesticide. It also includes any specified
derivatives, such as degradation and conversion products, metabolites and reaction
products which are considered to be of toxicological significance.
Good agricultural practices in the use of pesticides - is defined as the
officially recommended or authorised usage of pesticides under practical conditions at
any stage of production, storage, transport, distribution and processing of food and
other agricultural commodities, bearing in mind the variations in requirements within
and between regions, and which takes into account the minimum quantities
necessary to achieve adequate control, applied in a manner so as to leave a residue
which is the smallest amount practicable and which is toxicologically acceptable.
Tolerance limit - is the maximum concentration of a pesticide residue that is
recommended to be legally permitted in or on a food commodity. The concentration
is expressed in parts by weight of pesticide residue per million parts by weight of the
food or food commodity.
WHAT IS THE IMPORTANCE OF LABEL AND LEAFLET?
The importance of label and the information given in the leaflet cannot be over
emphasised. They provide the only method of direct transmission of technical
information, instructions and advice for the judicious and safe use of pesticides. The
safe and effective use of pesticides entirely depends on the completeness and clarity
of the statements made on the label, the users understanding of its instructions and
advice, and his compliance with them.
Classification of products by toxicity - Under the Insecticides Rules, the
toxicity category into which a formulated product falls is based primarily on its acute
oral and acute dermal toxicity to experimental animals and specifically on its acute
oral and dermal LD 50 values in rat. However, if toxicological or any other information
comes to the notice at any time signifying a greater or smaller hazard to the users
than that based solely on LD 50 data in the rat, the
5
Pesticides And Human Health
product may be ascribed to a higher or lower category or toxicity. Similarly if the
product’ dermal toxicity is so great as to ascribe it to a higher class than its oral
toxicity, the higher and more restrictive category is adopted.
As liquid products are likely to pose more spread and persistency of
contamination on the skin or on clothing than the solid products and more rapid
absorption into the circulation after contamination of the skin or in the gastro-intestinal
tract, they are assessed as per the WHO recommendation as 4 times more
hazardous than solid products.
The inhalational route of exposure is of greater importance in the case of
fumigants and also products liberated into the working atmosphere as gases or
vapours.
Label and leaflet contents:
The product and leaflet are intended to tell the purchaser and user:
What is in the container.
Who made or supplied the product.
Any legal responsibilities applying to the product.
The restrictions of its use.
For what biological problems it is to be used.
How it should be prepared, used and stored.
What type and degree of hazard it presents.
What precautions are needed before, during and after use.
What to do if adverse effects occur.
The required information to be given on the labels and in leaflets may be broadly
grouped into the following 3 categories :
1.
Product identity
The following factual information is provided on the label.
Name of the manufacturer.
Name of the insecticide, (brand name or Trade mark under which the insecticide
is sold).
Registration number of the insecticide.
6
Pesticides And Human Health
Kind and name of active and other ingredients and percentage of each (Common
name accepted by the International Standards Organisation or the Indian
Standards Institution of each of the ingredients shall be given and if no common
name exists, the correct chemical name which conforms most closely with the
generally accepted rules of chemical nomenclature shall be given).
Net content or volume, (The net content shall be exclusive of wrapper or other
material. The correct statement of the net content in terms of weight, measure,
number of units of activity, as the case may be shall be given. The weight and
volume shall be expressed in the Metric System).
Batch number.
Expiry date i.e., upto the date the insecticide shall retain its efficacy and safety.
Antidote statement.
2.
Directions for use :
The following details are given in the leaflet accompanying every packing of
an insecticide.
the plant disease, insect and noxious animals or weeds for which the insecticide
is to be applied, the adequate direction concerning the manner in which the
insecticide is to be used at the time of application;
particulars regarding chemicals harmful to human beings; animals and
wildlife, warning and cautionary statements including the symptoms of
poisoning, suitable and adequate safety measures and emergency first-aid
treatment where necessary;
cautions regarding storage and application of insecticides with suitable warnings
relating to inflammable, explosive or other substances harmful to the skin;
instructions concerning the decontamination or safe disposal of used
containers;
a statement showing the antidote for the poison shall be included in the
leaflet and the label;
if the insecticide is irritating to the skin, nose, throat or eyes, a statement
shall be included to that effect.
7
Pesticides And Human Health
3.
Hazards and precautions :
The following particulars are given on the label.
The label contains in a prominent place a diamond shaped square divided into
two equal triangles.
The upper triangle contains the symbol and signal
word/waming assigned to each toxicity category prescribed under the Rules.
The symbol and warning statements are:
insecticides belonging to Category I (Extremely toxic) contain the symbol of a
skull and cross bones and the word ‘POISON’ printed in red;
the statement “KEEP OUT OF THE REACH OF CHILDREN”.
The statement that “IF SWALLOWED, OR IF SYMPTOMS OF POISONING
OCCUR, CONTACT PHYSICIAN IMMEDIATELY”.
Insecticides in Category II (highly toxic) contain the worked “POISON” printed in
red and the statement “KEEP OUT OF THE REACH OF CHILDREN”.
Insecticides in Category III (Moderately toxic) contain the word “DANGER” and
the statement “KEEP OUT OF THE REACH OF THE CHILDREN”.
Insecticides in Category IV (Slightly toxic) contain the word “CAUTION”.
The lower triangle contain the colour specified to each toxicity category under the
classification of insecticides.
TREATMENT OF PESTICIDE POISONING
The most single important factor in the management of pesticide poisoning is
sound judgement. The emergency personnel who attend to the poisoning cases
cannot be expected to know instantly the dozens of modem pesticides, their
mechanism of action and the toxic effects they produce. It cannot be expected also
of the emergency personnel who attend to the poisoning cases to have all the clinical
and laboratory experience needed for the proper management of each case.
' 'DO
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05576
OOCUl*5 N'-AT’OH‘
7
8
Pesticides And Human Health
1. 0
ORGANOCHLORINE PESTICIDES
Insecticides:
Toxaphene.
Aldrin,
Chlordane, D.D.T., Heptachlor, Lindane and
Herbicides: Nitrofen
1.2.0 MECHANISM/SITE OF ACTION
Neurotoxic, CNS, Kidney and Liver.
1.3.0
ROUTE OF ENTRY
Ingestion, inhalation and skin.
1.4.0
SYMPTOMS
Nausea, vomiting, restlessness, tremor, apprehension, convulsions, coma,
respiratory failure and death.
1.5.0
TREATMENT
Do not induce emesis if the ingested poison is principally a
Hydrocarbon Solvent (e.g.Kerosene).
Gastric lavage with 2-4 L.tap water - Catharsis with 30 gm.(10 oz)
sodium sulphate in one cup of water.
Barbiturates in appropriate dosages repeated as necessary for
restlessness or convulsions.
Watch breathing closely,aspirate,oxygen and/or artificial respiration, if
needed.
Avoid oils, oil laxatives and epinephrine (Adrenalin) - Do not give
stimulants.
Give calcium gluconate (10% in 10ml, ampules) intravenously every
four hours.
9
Pesticides And Human Health
1.6.0
LABORATORY TESTS
No simple test, Assay of parent compound or know metabolite in blood, urine,
gastric contents or body tissues. Liver function tests.
2.1.0
ORGANOPHOSPHATE PESTICIDES
Insecticides: Acephate, chlorfenvinphos, diazinon, dichlorvos, dimethoate,
ethion, fenitrothion, fenthion, formothion, malathion, menazon, methyl parathion,
monocrotophos,
oxydemeton
methyl,
phenthoate,
phorate,
phosalone,
Phosphamidon, pirimiphos methyl, quinalphos, temphos, thiometon, trichlorphon.
Fungicides: Epiphenophos and kitazin.
Herbicides: Glyphosate.
2.2.0 MECHANISM/SITE OF ACTION
Anticholinesterase/cholinesterase inhibition.
2.3.0
ROUTE OF ENTRY
Ingestion, inhalation and skin.
2.4.0
SYMPTOMS
Mild - anorexia, headache, dizziness, weakness, anxiety, tremors of tongue
and eyelids, miosis, impairment of visual acuity.
Moderate - nausea, salivation, lacrimation, abdominal cramp, vomiting,
sweating, slow pulse, muscular tremors, miosis.
Severe - diarrhoea, pinpoint and non-reactive pupils, respiratory difficulty,
pulmonary edema, cyanosis, loss of sphincter control, convulsions, coma, and heart
block.
10
Pesticides And Human Health
2.5.0 TREATMENT
For extreme symptoms of O.P. poisoning, injection of atropine (2-4 mg.
for adults, 0.5-1.0 mg. for children) is recommended, repeated at
5-10 minute intervals until signs atropinization occur.
Speed is imperative
Atropine injection - 1 to 4 mg. Repeat 2 mg. When toxic symptoms
begin to recur (15-16 minute intervals). Excessive salivation-good sign
more atropine needed.
Keep airways open, Aspirate, use oxygen, insert endotracheal tube.
Do tracheotomy and give artificial respiration if needed.
For ingestion lavage stomach with 5% sodium bicarbonate, if not
vomiting. For skin contact, wash with soap and water (eyes - wash
with isotonic salient). Wear rubber gloves while washing contact area.
In addition to atropine give 2-PAM (2-pyridine aldoxime methiodide).
1g. and 0.25 g. for infants intravenously at a slow rate over a period of
5 minutes and administer again periodically as indicated. More than
one injection may be required.
Avoid
morphine,
phenothiazines.
theophyllin,
aminophyllin,
barbiturates
or
Do not give atropine to a cyanotic patient. Give artificial respiration
first then administer atropine.
2.6.0 LABORATORY TESTS
Estimation of cholinesterase in whole blood, plasma and R.B.C.
p-introphenol and total alkyl phosphate estimation in urine.
Estimation of parent compounds in gastric contents.
11
Pesticides And Human Health
3.1.0
CARBAMATE PESTICIDE
Insecticides: Aldicarb, carbaryl, carbofuran, propoxur.
3.2.0
MECHANISM/SITE OF ACTION
Anticholinesterase/cholinesterase inhibition.
3.3.0
ROUTE OF ENTRY
Ingestion, inhalation and skin
3.4.0
SYMPTOMS
Constriction of pupils, salivation, profuse sweating, lassitude, muscle
incoordination, nausea, vomiting, diarrhoea, epigastric pain, tightness in chest.
3.5.0
TREATMENT
Atropine injection 1 to 4 mg. Repeat 2 mg. When toxic symptoms
begin to recur (15-60 minute intervals). - Excessive salivation - good
sign, more atropine needed.
Keep airway open. Aspirate, use oxygen, insert endotracheal tube. Do
tracheotomy and give artificial respiration as needed.
For ingestion, lavage stomach with 5% sodium bicarbonate, if not
vomiting. For skin contact wash with soap and water (eyes - wash
with isotonic saline). Wear rubber gloves while washing contact area.
Oxygen
Morphine, If needed.
Avoid theophyllin and aminophyllin or babiturates.
2-PAM and other oxirties are harmful and in fact contra indicated. .
Do not give atropine to a cyanotic patient,
respiration first then administer atropine.
3.6.0
Give artificial
LABORATORY TESTS
Cholinesterase estimation in whole blood, plasma and R.B.C.
12
Pesticides And Human Health
4.1.0
COUMARINS / INDANDIONES
Warfarin, coumchlor
4.2.0
MECHANISM/SITE OF ACTION
Anticoagulant.
4.3.0
ROUTE OF ENTRY
Ingestion
4.4.0
SYMPTOMS
After repeated ingestion for several days: bleeding from nose, gums,
and into conjunctiva, urine a nd stool.
Possible pallor and petechial rash, late-massive echymoses or
hematoma of skin, joints, brain hemorrhage.
Shock and death.
4.5.0
TREATMENT
Lavage stomach with tap water. Catharsis 30 gm. Sodium sulfate in
250 cc tap water.
Vitamin K (mephyton or menadione preparation) by mouth,
intramuscularly or intravenously.Vitamin C may be useful adjunct.
Transfuse with fresh blood if bleeding is severe or until anemia is
corrected.
Iron (ferrous sulfate) by mouth for correction of secondary anemia, 0.3
gm. t.i.d.
4.6.0
LABORATORY TESTS
Prothrombin activity of blood plasma.
Blood in urine and faeces.
13
Pesticides And Human Health
5.1.0
ORGANIC ACIDS
2,4-D
5.2.0
MECHANISM / SITE OF ACTION
Liver, Kidney
5.3.0
ROUTE OF ENTRY
Ingestion
5.4.0
SYMPTOMS
Weakness and perhaps lethargy, anorexia, diarrhoea, muscle
weakness- may involve the muscles of mastication and swallowing.
Ventricular fibrillation and/or cardiac arrest or death.
5.5.0
TREATMENT
For ingestion, lavage stomach with tap water. For skin contact, wash
exposed area.
Supportive treatment.
Quinidine sulfate or quinine to relieve myotonia or suppress abnormal
ventricular cardiac rhythm.
5.6.0
LABORATORY TEST
No simple test. Only complex laboratory procedures.
6.1.0
HALOGEN FUMIGANTS
Methyl bromide
6.2.0
MECHANISM / SITE OF ACTION
Kidney, CNS depressant
14
Pesticides And Human Health
6.3.0
ROUTE OF ENTRY
Ingestion, inhalation, skin.
6.4.0
SYMPTOMS
Appear after four to twelve hours following inhaation. Symptoms
include dizziness, headache, anorexia, nausea, vomiting, and
abdominal pain. Lassitude, weakness, slurring speech and staggering
gait. Mental confusion, mania, tremors and epileptiform convulsions.
Rapid respiration, pulmonary edema, cyanosis, collapse, and death,
coma, areflexia, and death due to respiratory or circulatory failure, late
manifestations may include bronchopneumonia, pulmonary edema,
and respiratory failure.
Methyl bromide may produce cutaneous
blisters and kill via dermal exposure.
6.5.0
TREATMENT
In methyl bromide poisoning, early treatment with BAL (British Anti
Lewisite) may be considered if given before symptoms appear.
First remove patient from contaminated area.
Remove all contaminated clothing and wash contaminated skin. Can
penetrate ordinary rubber gloves.
Restrain confused
convulsions.
and
maniacal
patients.
Barbiturates
for
May require specific therapy for acidosis, pulmonary edema,
bronchospasm, (use epinephrine subcutaneously), respiratory
paralysis and/or kidney failure.
6.6.0 LABORATORY TEST
No simple test. Blood electrolytes to detect acidosis.
7.1.0
CYANIDE FUMIGANTS
Hydrocyanic acid
15
Pesticides And Human Health
7.2.0
MECHANISM/SITE OF ACTION
Cell Metabolism
7.3.0
ROUTE OF ENTRY
Ingestion, inhalation
7.4.0 SYMPTOMS
One of the fastest acting known poisons.
Massive dose - unconsciousness and death without warning. Smaller
doses - illness may last one or more hours.
Following ingestion, bitter, acrid, burning taste followed by constriction
of membrane in throat.
Salivation and nausea without vomiting, anxiety, confusion, and
dizziness.
Variable respirations - inspiration short and expiration prolonged.
Odor of bitter almonds in breath and vomitus. Initial increase in blood
pressure and slowing of heart followed by rapid and irregular pulse,
palpitation, and constriction of chest.
7.5.0 TREATMENT
If apneic, start artificial respiration. Keep airway open.
Inhalation of amyl nitrite (amyl nitrite perels) every 15-30 seconds
while 3% sodium nitrite solution is being prepared.
Intravenous injection (even of non-sterile solution) of 10 ml. Of 3%
sodium nitrite 2-4 minute period. Do not remove needle.
Through same needle give 50 ml of 25% solution of sodium thiosulfate
over 10 minutes.
If symptoms recur, repeat the nitrite and thiosulfate.
16
Pesticides And Human Health
Stomach lavage with 1:5000 potassium permanganate should follow
the above procedure.
Oxygen therapy and whole blood transfusions may be necessary if
nitrite induced mememoglobninemia becomes severe.
7.6.0
LABORATORY TESTS
No simple test. Send blocd to lab. For cyanide levels.
8.1.0
PHOSPHINE FUMIGANTS
Aluminium phosphide.
8.2.0
MECHANISM/SITE OF ACTION
Lungs
8.3.0
ROUTE OF ENTRY
Inhalation
8.4.0 SYMPTOMS
Nausea, vomiting, diarrhoea, great thirst, headache, vertigotinnitus,
pressure in chest, back pains, dyspnea, a feeling of coldness, and
stupor or attacks of fainting. May develop cough, sputum of a green
fluorescent colour.
Chronic poisoning may be characterised by anemia, bronchitis,
gastrointestinal disturbances, dental necrosses, and disturbances of
vision, speech and motor functions.
8.5.0
TREATMENT
No specific antidote. Keep patient quiet and warm. May need to treat
incipient pulmonary edema with venesection, oxygen, and hypertonic glucose
(50%) infusions. Intravenous isotonic solutions are contra indicated.
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Pesticides And Human Health
8.6.0
LABORATORY TESTS
None.
9.1.0
ARSENICALS
Sodium arsenite
9.2.0
MECHANISM/SITE OF ACTION
Cell metabolism
9.3.0
ROUTE OF ENTRY
Ingestion, inhalation
9.4.0
SYMPTOMS
- Thirty minutes to many hours, vomiting, profuse painful diarrhhea - bloody
later, colicky pains in esophagus, stomach and bowel, dehydration, thirst,
muscular cramps, cyanosis, feeble pulse and cold extremities, headache,
dizziness, vertigo, delirium or stupor, skin eruption, convulsions.
Three terminal signs:
Coma
General paralysis
Death
chief initial symptoms of ingestion are those of violent gastroenteritis,
burning esophageal pain, vomiting, watery or bloody diarrhoea
containing much mucous, later collapse, shock, marked weakness.
Death generally due to circulatory failure.
Inhalation: may cause pulmonary edema, restlessness, dyspnea,
cyanosis and foamy sputum.
9.5.0
TREATMENT
For ingestion lavage stomach with 2-3 L. of tap water and instill a glass of milk or
a 1% solution of sodium thiosulfate. For skin contact, wash with soap and water.
Acute symptoms will not develop except for sodium arsenite.
18
Pesticides And Human Health
Saline cathartic (15 to 30 gm).
BAL in a 10% solution in oil - instramuscularly:
Dosage schedule for BAL-(British Anti-Lewisite Compound) (2,3 Dimercapto -1 - Propanol or Dimercaprol).
Severe Poisoning:
1” day - 3.0 mg/Kg q4th (6 Inj.)
2nd day - 3.0 mg/Kg q4th (6 Inj.)
3rd day - 3.0 mg/Kg q4th (4 Inj.)
Each of following ten days (or until recovery).
3.0 mg/Kg q12 (2 Inj.)
Mild poisoning:
2.5 mg/Kg q4th (6 Inj.)
2.5 mg/Kg q6th (4 Inj.)
2.5 mg/Kg q12th (2 Inj.)
Check blood pressure and treat shock.
Isotonic saline for intravenous use to counteract dehydration.
Morphine may be needed for abdominal pain.
9.6.0
LABORATORY TESTS
No simple test. Save initial stomach contents and urine for arsenic analysis.
Urine may show red blood cells, albumin and casts. After arsenic inhalation,
urine shows hemoglobin.
PUBLIC HEALTH IMPORTANCE OF PESTICIDE RESIDUES
1.0.0
BACK-DROP
1.1.0
Pesticide residues in or on food and in the total environment are of great
concern to the scientific, governmental, industrial and public agencies.
19
Pesticides And Human Health
1.2.0
Many national governments have enacted laws regulating pesticide residues
in or on food, agricultural commodities or animal feed.
1.3.0
The basic objectives of regulating pesticide residues are:
(a) public health protection or consumer safety and
(b) prevention of environmental pollution.
1.4.0
Pesticide residues regulation has got three aspects:
(a) Legislation
(b) Setting Pesticide “Tolerance Limits” or “Maximum Residue Limits” (MRLs)
and
(c) Monitoring of residues in food and feed by residue analysis to ensure and
enforce compliance with recommended tolerance limits.
GUIDELINES FOR PREDICTING DIETARY INTAKE OF PESTICIDE RESIDUES
1. ACCEPTABLE DAILY INTAKE AND MAXIMUM RESIDUE LIMITS
The acceptable daily intake (ADI) of a pesticide is established on the basis of a
complete review of the available data (biochemical, metabolic, pharmacological,
toxicological, etc.) from a wide range of experimental animal studies and
observations in humans. The no-observed-adverse-effect level (NOAEL) for the
most sensitive toxicological parameter, normally in the most sensitive species of
experimental animal, is used as the starting-point. A safety factor that takes into
consideration the type of effect, the severity or reversibility of the effect, and the
problems of inter-and intra-species variability is applied to the NOAEL to
determine the ADI for humans.
Pertinent human data may outweight
experimental animal data in the estimation of the ADI for man.
2. PREDICTING THE DIETARY INTAKE OF PESTICIDE RESIDUES
General considerations
In order to reach a conclusion as to the acceptability of an MRL from a public
health point of view, it is necessary to predict the dietary intake of pesticide residues
20
Pesticides And Human Health
resulting from application of the MRL, and to compare this prediction with the ADI.
The dietary intake of any particular pesticide residue in a given food is obtained by
multiplying the residue level in the food by the amount of that food consumed. Total
intake of the pesticide residue is then obtained by summing the intakes from all
commodities containing the residue concerned.
Indices of residue level
Several indices of residue level can be used to predict pesticide residue
intake. The MRL is one such index and represents the maximum residue level that is
expected to occur in a commodity following the application of a pesticide according to
good agricultural practice. Factors that may be taken into consideration when
choosing an index to be used in predicting pesticide residue intake include the
residue levels found in practice, their distribution in the commodity, and the effect on
residues of the various processes used in the preparation of food.
It should be appreciated that the use of the MRL in the prediction of pesticide
residue intake will lead to an overestimation of actual pesticide residue intake .
The prediction of intake of a particular pesticide residue should include all
commodities for which MRLs have been established, unless the value has been
estimated to be at, or about, the limit of determination.
Indices of food consumption
There are several possible indices of food consumption, a commonly used
index being the average daily consumption. Others include average portion sizes,
percentile consumption values, and the average consumption by people who actually
eat the commodity. In predicting pesticide residue intake an effort should be made to
reflect long-term food consumption habits and not day-to-day variations, in order to
permit a valid comparison with the ADI, which is based on acceptable intake over a
lifetime. Thus, it is recommended that average daily food consumption values be
used in predicting pesticide residue intake for comparison with the ADI.
Food consumption patters vary considerably from country to country and even
within a country; thus, to a large extent, individual countries will have to estimate their
own consumption pattern.
21
Pesticides And Human Health
In order to predict pesticide residue intake at the international level,
hypothetical diets will need to be developed for a number of dietary patterns that are
representative of various regions of the world (“cultural” diets). As a first
approximation, a hypothetical global diet consisting of the highest average value of
food consumption for each “cultural” diet may suffice. Selection of this value for
individual commodities from each “cultural” diet will, however, result in an unrealistic
total food consumption. For the prediction of pesticide residue intake, these values
should be normalized to a total daily consumption of 1.5 Kg of solid food, i.e.,
excluding the liquid content of juices or milk.
For more realistic predictions, the “cultural” diets should be used individually.
This would make it possible to predict a range of potential intakes.
For predictions of pesticide residue intake earned out at the national level, the
best available food consumption data should be used. Countries should be cautious
in the use of food consumption values other than average values, if such use results
in a hypothetical level of consumption that would not be attained in practice. In
carrying out predictions of pesticide residue intake for identifiable subgroups,
e.g..vegetarians, it would be appropriate to use relevant average food consumption
data for such subgroups.
Assessment of intake
Pesticide residue intake through the diet can be predicted with different
degrees of accuracy.
However, the more realistic predictions involve the
consideration of many factors and therefore may be rather time-consuming. The
options in the process are shown :
1.
Options for the prediction of dietary intake of pesticide residues
Measured pesticide residue intake
“Best estimate” - estimated daily intake (EDI)
“Intermediate estimate” - estimated maximum daily intake (EMD)
“Crude estimate” - theoretical maximum daily intake (TMDI)
22
Pesticides And Human Health
The procedure discussed here start with the most exaggerated and proceed
towards more and more realistic intake predictions. It should be noted that the less
realistic predictions, which are relatively straight forward to carry out, give an
overestimate of the true pesticide intake. By starting with the most exaggerated
predictions, it is therefore possible to eliminate at an early stage pesticides whose
intake is clearly unlikely to exceed the ADI. More realistic predictions using refined
data then make it possible to eliminate other pesticides from further consideration.
Such an approach would facilitate acceptance of MRLs for the majority of pesticides
and allow the national authority concerned to direct its attention to those most likely to
be of public health concern. The three-tier approach to predicting pesticide residue
intake is outlined :
2.
Outline of procedures for predicting pesticide residue intake
Residue level
Food
Consumption
TMDI*
EMDI “
EDIb
Codex or national
MRL
Codex or national
MRL
Corrections for:
(i) edible portion;
and
(ii) losses on storage,
processing and
cooking
Known residue level
Corrections for:
(i) edible portion;
and
(ii) losses on storage,
processing and
cooking
Hypothetical global
National diet
“cultural”
or National Diet.
National diet
All commodities
with a Codex or
National MRL
All commodities
with a Codex
National MRL
Known use of
Pesticide, taking
account of:
(i) range of
Commodities;
(ii) proportion of
crop treated; and
(iii) home-grown
and imported crops.
* May be estimated at either the national or international level.
b Can be estimated only at the national level.
23
Pesticidas And Human Health
" The safety issue can never be settled by polemics or by fiat. In
the ultimate analysis the good health of our farmers and the
wholesomeness of our food supply can be guaranteed only
by a scientific and medical community that stays alert
-DR.ROBERT E. GOSSELIN
Further Suggested Reading:
1.
Dr. D.P. Nag, Know Your Pesticides - Technical Report, 1985
Publ: Directorate of Plant Protection, Quarantine and Storage, Govt, of India.
2.
Dr. D.P. Nag, Treatment of Pesticide Poisoning - Technical Report, 1985
Publ: Directorate of Plant Protection, Quarantine and Storage, Govt, of India.
3.
FAO/WHO (1998): Pesticide Residues - 1998 Evaluations.
4.
FAO/WHO (1999): Dietary Intake of Pesticide Residues.
CHALLENGES OF
AGRICULTURAL MEDICINE
FOR THE PHC DOCTOR
by
Dr. Ravi Narayan, MD, DTPH (London) DIH (UK)
Community Health Cell
Society for Community Health Awareness Research and Action,
367, Srinivasa Nilaya, Jakkasandra I Main, I Block Koramangala,
Bangalore - 560 034.
Tel: 553 15 18/ 552 53 72
Fax: (080) 553 33 58 {Mark Attn: CHC}
Email: sochara@blr.vsnl.net.in
Presented at the WHO Sponsored Training Programme on
“OCCUPATIONAL HEALTH IN AGRICULTURAL SECTOR”,
Organised by Regional Occupational Health Centre
(Indian Council of Medical Research), at Bangalore,
during 8-12 February 1999.
I
CHALLENGES OF AGRICULTURAL MEDICINE FOR
THE PHC DOCTOR
A) THE CONTEXT
1. The Agricultural Worker forms more than 70 per cent of the working
population in almost all countries of Asia. In India, in the 1981 Census, 42.06
percent were cultivators, 26.31 per cent were agricultural labourers and 2.22
per cent were engaged in plantations, livestock and forestry, bringing the total
employed in agriculture and related operations to 70.6 percent. The pattern in
the 1991 Census was not very different.
2. Reviews of Occupational Health Research in India and worldwide show
however that agricultural work is one of the most neglected areas of research
and compared to the amount of information on industrial workers and hazards
of industrial environments, there is little information on Hazards of
agricultural related occupations. Since the seventies, however, this situation is
beginning to change.
3. Agriculture today is becoming a new focus of health research because of a
series of factors.
a) Largest work-force
In spite of mechanization and industrialization of Agriculture in the west,
and the transfer of the so-called Green Revolution technology to the
Developing World, Agriculture continues to remain the main
occupation of a large majority of the workers of the world.
b) Modernization of traditional agricultural practices. This has included a
combination of the following developments:
improvement of irrigation facilities by construction of dams and canal
systems;
introduction of High-yielding varieties of seeds for foods and cash
crops;
increased use of agrochemicals - both fertilisers and pesticides;
a genetic upgradation of livestock;
a shift from subsistence economy to cash cropping including a shift
from produce for local use to produce for export;
increasing mechanization of agriculture;
a diversion of land resources to generate raw materials for the
concomitant industrialization.
Whereas, it was assumed that increasing GNP of the country and the
purchasing power of rural poor would be the results of massive hightechnology agricultural development and that this would improve health
2
and nutrition of the people - this equation proved to be more complicated
in actual practice.
c) Occupational Hazards and Social costs of Agricultural Development
An increasing number of studies have begun to indicate that the side
effects and social costs of many agricultural policies are detrimental to
health. These detrimental social costs documented today include
occupational and environmental dangers of pesticide use and overuse;
changes in vector ecology, environment and disease patterns in the
community;
the increase in disabling accidents;
the marginalisation of the rural poor;
the deterioration in the quantity and quality of the local diets;
the dangers from mycotoxins;
the resurgence of old diseases like malaria and the spread of new ones
like Japanese encephalitis.
Occupational health hazards in Agriculture is thus a complex mosaic of
not only the known hazards of traditional agricultural practices but the
newer and ever increasing hazards of modernization and industrialization
of agriculture. The challenge of Agricultural Medicine is therefore
very complex.
d) Complexity of work environment
Unlike the industrial environment where it is easy to define jobs and
identify localised risks and study hazards to health usually in adult
subjects, the Agricultural environment is very complex and needs a more
complicated research methodology and a more complex health care
management. The study of hazards in agriculture is complicated by:
the plurality of a worker's job;
the participation of most members of the family in work including
women and children;
the seasonality in the quantity and quality of work;
and, the multiplicity of hazards affecting a stratified community of
landed farmers and landless labourers differently.
I
This complex situation needs a research methodology very different from
those employed in Industrial medical research. The methodology has to be
multifactorial, multivariate, interactive, explorative and participatory. It is
only in recent years that these methodologies have developed and hence
the resurgence of research in Agriculture. Some years ago, efforts were
made to evolve a framework to understand the effects of Agricultural
development on vector borne diseases. (See additional background paper
entitled “Epidemiological patterns associated with Agricultural activities
3
in the tropics”, which highlights some aspects of the complexity of this
framework.)
This complex situation also demands a multidimensional understanding
among the practitioners of Agricultural Medicine and a multidimensional
response of the Health Care System to tackle the problems of Agricultural
Medicine and Health.
B) THE CHALLENGES OF AGRICULTURAL MEDICINE
1. Key issues
This course will cover a wide range of challenges. A list of 15 key issues that
can be a check list for you to identify and classify the potential challenges
(Adapted from M.J. Coye, 1988) is enclosed.
The industrialisation of Agriculture and the epidemiology of agricultural
change
2. The increasing role of hired, seasonal and migrant labour and their
epidemiological significance
3. Mechanisation of Agriculture
4. Chemicalisation Agriculture
5. Emerging knowledge of ‘Health status’ of Agricultural workers or sub
groups.
6. Malnutrition and other nutritional deficiency.
7. Agricultural accidents.
8. Illness groups
a) Mortality
b) Musculoskeletal disorders
c) Heart stress syndromes
d) Dermatitis
e) Pesticide related illness
f) Vector borne diseases and zoonoses
g) Cancers
h) Psycho-social effects
i) Other diseases.
9. Inadequate worksite sanitation and Health and Safety Systems.
10. Inadequate 'Rights to Know’ and social security.
1.
All these are challenges today, in the Indian Agricultural scene as well.
2. Case studies
A series of 8 case studies from literature in the 1970s and 1980s is presented
below as an indication of the problems and challenges that were predicted more
than two decades ago. Are we continuing to neglect these problems?
4
1. Pesticide Hazards
“Pesticides are of immense value to our agricultural and public health
programmes for increasing production and for controlling vectors of certain
diseases. No accurate data are available on the morbidity and mortality from these
toxicants. However, the records of health and agricultural departments of
different states and union territories as summarised in the Council of Agricultural
research of 1967 indicate that pesticides have been responsible for various toxic
effects in human beings and live stock"
- Indian Council of Medical Research (1975)
2. Japanese Encephalitis
"Japanese encephallitais is caused by a virus carried by a species of culicine
mosquito which breeds in the standing water of paddy fields. With increase in the
area of rice cultivation, multiple cropping and flooding of more land, the habitat
of the mosquitoes has increased. This has leads to a marked increase in their
population and the incidence of Japanese encephalitis."
Ministry of Health and Family Welfare 1975
3. Epidemic Genu Valgum
“Water seepage from the reservoir of the Nagaijunsagar dam and its canals have
increased the level of subsoil water. This in turn, has changed fluoride, calcium,
molybdenum (Mb), zinc and magnesium composition of the soil. This has
resulted in a suitable condition for higher intake of Mb by sorghum plants. For
people consuming sorghum a staple, this has meant higher intake of Mb and as a
consequence high copper excretion leading to copper deficiency”. Associated with
high fluoride intake - skeletal fluorosis has been endemic in this area - now this
has meant an acute epidemic of genu valgum - knock knees".
Indian Council of Medical Research (1977)
4. Mycotoxins
"The danger from mycotoxins is specially high in developing countries of the
world because of climatic conditions which are favourable for mould growth and
inadequate pre- and post-harvest practices which promote elaboration of toxins in
staple foodgrains. Also, widespread under-nutrition in these countries may render
the population more susceptible to hazards of mycotoxins".
Indian Council of Medical Research (1978)
5
5. Handigodu Syndrome
“In 1975, health authorities in the Malnad area of Karnataka in South India began
to report a mysterious new disease. For the victims, it began with intermittent
pain in the hip and knee joints which later became continuous until some could
hardly stand up. This crippling deformity - Endemic Familial Arthritis of Malnad
(EFAM) appears to be limited to pesticide use. The people affected by EFAM
were all poor people of low caste. At certain times of year especially when food
is short the poorer villagers eat crabs which are found in the rice fields.... These
same paddy fields were increasingly contaminated with pesticides including
parathion and endrin. Due to inbreeding and special genetic characteristics, the
people of Malnad were particularly susceptible to the apparent effects of
pesticides residues in the environment, consumed via the paddy field crabs”.
Indian Council of Medical Research (1980)
6. Malnutrition
"Although most Third World countries are basically agricultural, the existing
patterns of agricultural development have resulted in inadequate food supply which means that a large proportion of essential foods ae imported. Moreover,
food distribution within these countries is highly unequal, with the richer families
in the rural areas and the urban middle and upper classes consuming a
disproportionately greater share of the food supply. The poor including the food
producers themselves, consequently suffer a deterioration in both the quantity
and quality of their food intake".
Third World Network (1985)
7. Agricultural accidents
"An official estimate states that about 1,000 farmers are injured throughout the
country during the wheat harvesting season. The chief culprit is the thresher. The
largest government hospital in Delhi admitted 2,000 such patients between 197981 and 117 returned without a limb. A recent survey by the Department of
Agriculture showed that overall rate was 25 accidents per thousand machines."
Medico friend circle (1986)
8. Malariogenic Development
"Besides development of insecticide resistant mosquitoes and drug resistant
organisms, environmental changes brought about by canal irrigation led to
waterlogging and the formation of puddles which were good breeding grounds for
mosquitoes. Similarly, a study form Tamilnadu shows that Sathanur reservoir and
vicinity accounts for 51% of all the malaria cases in the state. The heaviest
concentration of cases is found in villages situated within 5 kms of the river.
Most of these villages were free from malaria for nearly twenty years".
- Medico friend circle (1986)
6
C) SOME GUIDELINES ON AGRICULTURAL MEDICINE” FOR THE
PHC DOCTOR - TO MEET THE CHALLENGES
* As a PHC Doctor, you are part of the Primary Health Care strategy of the
government which includes First Line clinical care, Mother and Child Health,
Family Planning, Communicable Disease Control, Health Education, School
Health, Environmental Sanitation, Vital Statistics and Management
Information Systems, establishing referral systems and enabling community
organisation and participation.
* However, since the culture/economy of the Rural areas is so closely linked to
Agriculture and Agricultural development - the Health problems of
Agriculture and the ‘positive’ and ‘negative’ effects of Agricultural
development will be an area of growing importance in your work.
‘Agricultural Medicine’ will therefore emerge as a growing challenge in your
work.
# To prepare you for this challenge a 6 point guideline is suggested:
1. As a Doctor working in a Rural Area, you should take a healthy
interest in Agriculture and the changes that are taking place in it over
the years, in your areas. This could include:
i.
What are the crops being grown in your area?
food crops or cash crops? and the balance between them
ii.
What is the type of irrigation in the area?
Does this predispose to any particular type of vector borne disease or
health problem? Malaria, Filaria, JE, Guinea worm?
iii.
What are the chemicals being used for agriculture in your area?
Pesticides, Fertilizers, Herbicides, other chemical agents.
Are there any problems with chronic handling of these?
Are there acute hazards in their use/over use/misuse?
Are they commonly used for suicide? Poisoning?
iv.
What is the type of land ownership and land use patterns in
your area? and the system of minimum wages? bonded
labour?
Do they predispose to increasing poverty, malnutrition, economic
insecurity, marginalisation? Are there seasonal patterns? Do these
determine illness patterns that you see in your OPD?
7
2. Keep your Eyes/Ears/Minds open to unusual patterns of disease or
emerging medical/health problems.
(>)
(ii)
(iii)
Are there new patterns of disease? new symptom complexes?
unusual case presentations of known disease? New 'Mystery'
disease? Unusual types of recurring accidents or injury?
What are people saying about local illness patterns?
What linkages are mentioned? Do specific occupational sub-groups
mention specific or special problems?
Can these new patterns or occurrences be linked to any specific
local development in agriculture? Climate change? development
change?
3. Disaggregate your routine collected Health statistics and check patterns
and ask why?
look at differences in class, caste, land ownership, income, gender,
geographical distribution, etc.
High mortality or morbidity in special sub groups may be due to a special
health problem related to local occupations.
4. Keep yourself well informed about changing patterns of known problems
and dynamics and nature of new emerging medical/health problems and
what can be done at primary health care level?
The sources of information are many - newspapers and popular magazines;
TV and radio, professional journals, CMEs by professional associations.
Don't be a passive recepient off information. Actively seek and search for
relevant materials.
Write to resource centres, medical college, health directorate, professional
associations for information/guidelines.
Do not rely only on what the Medical representatives say.
Do not let 'market forces' and market economy' determine your choice of
action or solutions - but technical factors, cost to patient; effectivity; and
other rational factors should determine choice.
5. Inform authorities about observations, impressions; inferences; concerns
These authorities should not only be the Health directorate, but other
departments as well as in an intersectoral context - Agriculture, irrigation,
education, women's development; child welfare; panchayatraj; rural
industry and so on.
Write to medical colleges, research institutions, professional associations?
You are their eyes/ears at the grass root levels?
8
Do not just be passive recepient of expert guidelines or prescriptions from
top down processes’. Give feedback or suggestions on local adaptations;
local modifications of guidelines; new guidelines, alternative guidelines.
6. Develop knowledge skills and attitudes in your health team that will help
your team to tackle problems of Agricultural Medicine at the PHC level
at primary, secondary or tertiary levels of prevention
do you know the antidotes to the common chemical poisons available in
the rural area
is your lab geared to make basic lab diagnosis for common priority
problems?
are you including awareness raising or information on some chemicals etc.
in your health education programmes
are you prepared for disasters such as seasonal epidemics, drought, floods
and so on.
if you were requested to give a health impact assessment of a
agricultural/rural industries development strategy/programme in your area,
do you know the basic protocol of investigations to give such an expert
view
is your team skilled in organising the community using local leadership to
enhance the participation of the local community in your programme and
initiatives.
In conclusion,
This comprehensive course organised by Regional Occupational Health Centre
is a significant opportunity to develop this knowledge and expertise and be
sensitised to emerging health challenges. It has included -
Occupational health problems of agriculture; respiratory problems among
sericulture workers; occupational lung disease; grain dust problems; TB;
Ergonomic problems; pesticides; occupational cancers; Alcoholism; surgical
wounds; problems of poultry workers, and dairy workers; problems of safety;
cardiac diseases; problem of coir, agarbathi, tea plantations and a wide range
of issues. This is a very comprehensive sensitization process. Your active
interest and concern to develop this field further is urgently required.
From a Primary Health Centre Doctor to a well informed practitioner
ofAgricultural Medicine - Are you ready for this metamorphosis as we
reach 2000 AD? The challenge is an opportunity!
9
Further Reading:
1. Narayan, Ravi, Ramachandran. C.R. et al (1982)
Health Status of Tea Plantation Workers with special reference to their occupation, ICMR
Joint study by Ross Institute Unit of Occupational Health and regional Occupational
Health Centre (Part I of the Report, 1982).
2. Bradley D.J. and Narayan, Ravi (1987)
Epidemiological Patterns associated with agricultural activities in the tropics (paper co
authored with Professor David J. Bradley, Ross Institute, London) for joint WHO / FAO
/ UNEP Panel of Experts on Environmental Management for Vector Control: Meeting in
Rome, September 1987. (Effects of Agricultural development on Vector Borne disease,
FAO Monograph Agl/Misc/12/87).
3. Narayan, Ravi (1987)
Health, Nutrition and Agricultural Development - an overview of the situation in
Karnataka sabbatical assignment, London School of Hygiene and Tropical Medicine,
London.
4. I.C.M.R. (1975). Pesticide Pollution and Health Hazards. ICMR Bulletin. Vol.5, No. 12,
December 1975.
5.
Medico Friend Circle (1986). Issues in Environmental Health : The case of pesticides.
Mfc annual meet - 1986 papers, a ced-mfc publication.
6. Third World Network (1985). Third World - Development or crisis? Declarations and
conclusions of the Third World Conference, Penang, Malaysia, 1984. Third World
network publication.
7. Indian Council of Medical Research (1978). Health hazards of mycotoxins in India.
Ramesh V. Bhat et al. National Institute of Nutrition, Hyderabad report, 1978.
8. David Bull (1982). A growing problem - Pesticides and the third world poor. Oxfam
publication.
9. Centre for Science and Environment (1985). The state of India’s Environment 1984-85
the second citizens report. CSE, New Delhi.
10. Coye, M.J. (1985) The Health Effects of Agricultural Production : 1 the Health of
Agricultural workers, Journal of Public Health Policy, September 1985, p 349-370.
10
ROHC-WHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999: L.N.-10
Cancer Scenario in Rural India with a Brief Review of
Cancers in Farm and Agricultural Workers.
DR. M. DHAR & DR. A. NANDAKUMAR
Coordinating Unit of the National Cancer Registry Program, I.C.M.R., Kidwai
Memorial Institute of Oncology, Post Box. No. 2930, Hosur Road, Bangalore 560 029.
Many of the studies in the field of cancer epidemiology/registration in India
have been confined to the urban population mainly due to non-availability of
sufficient data on cancer incidence in rural population. The National Cancer
Registry Program (NCRP) of Indian Council of Medical Research has got only two
rural registries, and as of now validated data is available from only one of them.
Thus, there is very little available for the researchers interested in observing
cancer patterns in a rural population. As, an alternative, this study uses the data
on permanent place of residence collected by Hospital Cancer Registries (HCRs)
under NCRP. The patients registered at different HCRs were classified by, type of
residence whether urban or rural with the help of list of towns categorized as such
by census of India 1991 and the directory of postal index numbers (PIN)
published by Department of Posts, India. The objectives of this study are to study
the differentials by type of residence in relative magnitude, diagnosis and clinical
extent of disease in cancer patients of leading sites.
This study uses the data collected by Hospital Cancer Registries (HCR) to
determine differences if any, in the pattern of cancer according to type of
residence whether urban or rural. The definition of 'urban/rural' was obtained from
the publications of the Census of India and the list of towns provided in it were
matched with the list of Post Offices in the respective states to get pin codes. The
HCR proforma provides information on the PIN codes of residence of patients.
These were matched using computer programs to obtain urban/rural divide of
patients and the cancer pattern through relative frequencies were obtained.
Three registries namely, Bangalore, Madras and Trivandrum located in
Southern part of the Country were included in the study. The proportion of
urban/rural cases were 83%, 62% and 42% respectively. The total number of
cases for analysis was 91521. The ranks of 5 leading states of cancer remained
more or less the same in both urban and rural populations in either sex in three
HCRs. However, when one looked closely at the figures of relative frequencies
(percentages) a higher proportion (2 - 5 %) of cancers of the oral cavity was
observed in the rural population of all the HCRs and in both sexes. A six- percent
higher proportion of cervix cancers was observed in the rural population of HCR
Madras. Both HCR Madras and Trivandrum showed a higher proportion (5 and
3.5% respectively) of cancer of the breast in the urban population
2
Cancer Scenario in Rural India with a Brief Review of Cancers in Farm and Agricultural Workers
compared to the rural population. The proportion of patients with advanced or
localized disease showed some variation between urban and rural areas for
certain sites. For example, rural population had higher proportion of advanced
oral cancers and the urban had higher localized cancers of the breast in
Bangalore.
Insecticides in general and carbamates and phosphates in particular (ORs
2.5 CI: 1.1 - 5.6; 3.08, 1.1 - 9; 3.0,1.3-6.9) showed a significant risk for CI_L and
low grade NHL (Nanni et al). Kristensen et al have reported a significant
association between dairy farming and acute leukemia (1.8, 1.0-3.5). A cancer
registry based study of occupational risk for lymphoma, multiple myeloma and
leukemia by Brownson and Reif showed that farmers had slightly elevated risk for
NHL (1.11) and HD (1.3) and a higher elevated risk for ALL (2.84). Franceschi
et al reported that those agricultural workers exposed to herbicides and pesticides
had a significantly elevated risk (3.2, 1.6-6.5) for the development of Hodgkin's
Disease. A meta analysis of 32 studies of multiple myeloma and farming
according to three different methods by Khuder and Mutgi yielded estimated
relative risks of 1.23, 1.23 and 1.38 (all three being significant). The authors
conclude that such consistent positive findings suggest that there is an
association between MM and farming. Exposures commonly experienced by
farmers and that might contribute to the occurrence of MM include infectious
microorganisms, solvents and pesticides. A similar study on NHL yielded a
combined risk of 1.26 (1.2-1.4).
ROHC-WHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999: L.N.-12
Change In Trends In Alcoholism
DR.G.S.PALAKSHA
Chief Medical Superintendent, Psychiatrist, H.A.L. Hospital, Bangalore-560017.
Alcohol consumption is on the increase, both in adults and in children,
both in Western and Eastern cultures. The citizens of rural areas are not lagging
behind the urban citizens. There is an increase in the incidence and
prevalence of alcoholism and related physical and mental disorders among
the rural population. The mortality and morbidity are on the increase among the
rural population due to various reasons. Even though the ultimate mortality due
to alcoholism is unchanged among the urban alcoholics, morbidity is on the
increase because of early therapeutic intervention, availability of various
methodologies in the treatment of alcoholism. There are many reasons for the
increase in consumption of alcohol:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
Easy availability of alcohol
Availability of variety of alcoholic beverages
Improved economy
Industrialisation
Curiosity
Learning from other alcoholics
Peer group
Stressors
Negligence of children
Other drug abuse
Relief from anxiety
Relief from unhappiness
Failure to identify other coping methods for stressors
Genetics
Who Is An Alcohol Dependent?
Any consumer who has three or more of the following symptoms occurring at
any time in the same 12 months period is considered as an alcohol dependent.
1.
Tolerance: increased amount of alcohol consumption to experience the
same desired effects.
2.
Withdrawal (vide infra):
2
Change In Trends In Alcoholism
3.
Desire to consume alcohol:
4.
Alcohol obtaining important : An
obtain alcohol.
5.
Social changes in connection with alcohol use
6.
Alcohol related disabilities that do not lead to sobriety
7.
Continued use of alcohol despite exacerbation of health problem
8.
Avoidance of important social,
because of alcohol use
9.
Negligence of duties towards family
alcoholic
discovers various ways to
professional
or recreational events
Drinking History
1.
■'C”
3.
"A" - Have you ever been "annoyed" by any ones comments about
your drinking?
3.
"G" - Have you ever felt "Guilty" about your drinking?
4.
"E" - Have you ever had an "Eye-opener" in the morning?
- Have you ever tried to "cut down" on your drinking?
Two positive answers are suggestive of alcoholism which prompt a detailed
workup.
(Daily heavy drinking is more likely to produce physiologic dependence than
intermittent / light drinking).
How To Identify An Alcoholic?
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Tachycardia
Puffiness of face
Flushing (rhinophyma)
Increased perspiration
Tremors
Easy bruising
Nail infection
Spider angiomas
Dyspepsia
Fatigue
3
Change In Trends In Alcoholism
11. Unwarranted irritability
12. Frequent absenteeism/dismissals (negligence of duties)
13. Frequent accidents
End Organ Damage
A variety of diseases involving virtually every organ in the body is associated
with excessive consumption of alcohol.
I
CNS
Wernicke-Korsakoff syndrome - This is due to thiamine deficiency. Acute
or sub-acute disorder characterized by severe mental confusion, apathy,
drowsiness, ataxia, chronic amnesic stage, prolonged loss of the ability to store
new information,disorientation, unresponsiveness, derangement of perception
and memory, exhaustion, dehydration, profound lethargy, confabulations,
occulomotor impairment(nystagmus, sixth nerve palsy, paralysis or conjugate
gaze)
II
Liver
A.
B.
C.
D.
Fatty Liver (seen in 90% of cases)
Alcoholic hepatitis & fibrosis (40%)
Cirrohosis (15-30%)
Hepatoma
Serious forms are more common in women than in men.
III
CVS
a)
b)
c)
d)
e)
Coronary artery disease
Hypertension
Cardio myopathy
Various arrythmias
Certoro vascular hemorrhage
Both drinking and withdrawal can raise the blood
abstinence blood pressure usually declines.
pressure, but with
"Holiday heart" - paroxysmal atrial fibrillation seen in the conjunction with
alcohol consumption.
4
Change In Trends In Alcoholism
III
Reproductive system
Alcohol suppresses testosterone level after as few as 5 days of heavy
drinking.Alcohol dependence may cause testicular atrophy, impotence, loss of
libido.
Causes of amenorrhoea, anovulation and early menopause. Impairs fertility or
spontaneous abortion.
Fetal Alcohol Syndrome
Occurs one in thousand to three thousand live births. Growth retardation,
neurologic abnormalities and characteristic facies are seen
IV
Gastrointestinal system
1. Oesophageal and hepatic ulcers
2. Carcinoma of tongue throughout esophagus and stomach
3. Frequent diarrohoea - dehydration
4. Pancreatitis, acute, subacute and chronic
V
Muscles: Myalgia, acute and chronic
VI
Lungs
1. Bronchitis, acute and chronic
2. Carcinoma of the lung
VII
Peripheral nerves
Pain, tingling sensation and numbness
VIII
Sleeplessness
Psychological Illness
Alcohol withdrawal syndrome
Due to fall in blood alcohol level, severity depends upon daily intake, duration
of alcohol consumption, the age of the consumer, physical ad mental health of
the individual and history of withdrawals.
5
Change In Trends In Alcoholism
Delirium Tremens (D.T.)
This is the most serious of the alcohol withdrawal phenomena with a
mortality rate of upto 2-5%. Prediction : it is difficult to predict who will develop
D.T. infection, head trauma, poor nutrition, rum fits, previous episodes of D.T.
are the contributing factors towards D.T. more than one out of every three
patients who suffer fits develop subsequent D.T.
Clinical Features
If D.T. is to occur, it generally does so within 24-72 hours after withdrawal but
can appear even after a week of withdrawal. D.T. presents in a dramatic manner
and appears to have had an explosive onset. It onsets usually at night. The
following clinical features are usually observed in D.T.
Clinical Features Of D.T.
1. Loss of appetite
2. Irritability
3. Tremors
4. Hypervigilance
5. Insomnia
6. Illusions
7. Hallucinations
D.T. Lasts for 10-150 hours.
Management Of D.T.
IP. Vs O.P.
Fluid replacement, atleast 6 lit./ day
Sedation, chlordiazepoxide, 25-100 mgm, tds/qid
Thiamine, WOrngm, 1-3 times/day
High potency vitamin preparation
Head injury, if present should be managed
Rule out infection
Rule out concomitant consumption of other sedatives
(especially barbiturate)
Treat hypoglycemia with glucose
Monitor serum electrolytes, blood urea, CBC
Order for LFT, Hbs Ag and ECG
Half hourly TPR chart
Decrease stimulation
Magnesium sulfate 1 gram I.M. 6th hourly for 2 days
Phenytoin or carbamazpine to be given routinely when there is past history
of rum fits
6
Change In Trends In Alcoholism
Out Come Of D.T.
Usually short lived, lasting less than three days
Terminates in a prolonged sleep
Rarely prolonged
Death due to CVS collapse, infection hyperthermia or self injury
The disorder is usually short lived lasting less than three days in the majority of
cases. Very rarely recurrent phases may be seen over a longer period of
time. D.T. typically terminates in a prolonged sleep after which the person
feels fully recovered apart from residual weakness and exhaustion. Rarely,
prolonged attack of D.T. may clear to reveal an amnesic syndrome when
Wernicke's encephalopathy had been present, unnoticed during the acute stage
mortality of patients with epilepsy and alcoholism is considerably higher than
that of other group of patients with epilepsy. Death when it occurs is due
to cardiovascular collapse, infection, hyperthermia or self injury during the
phase of intense restlessness.
Any infective process and particularly
pneumonia markedly increases the mortality.
Alcoholic Dementia
An organic syndrome
Prolonged and heavy alcohol use
Seen in about 8-9% of alcoholics
Persistence of dementia for atleast 3 weeks after
drinking ceases &, exclusion of all other causes of dementia
Clinical Features
Deterioration in past intellectual abilities
Short and long term memory deficits
Impaired abstract thinking
Poor judgment
Impulse control of sufficient magnitude to interfere
significantly with work, usual social activities or
relationship with others
No loss of consciousness
Delusions /hallucinations
Absence of insight
Incontinence, impaired mastication and swallowing during end stage
7
Change In Trends In Alcoholism
The demented persons of rural areas may not be brought for immediate
medical care due to inadequate knowledge of the family members about the
illness or due to submitting the sufferers to "faith healers" or other modalities
of treatment.
Treatment Of Alcohol Dependence
1.
Counseling, involvement of the family members and close associates is
beneficial. Educate thoroughly regarding the ill effects of alcohol. Trace
the sources of alcoholism and try to modify it. Strengthen the inner
personal intimacy. Involve previous alcoholic as a good role model.
2.
Religious invoivement, with the involvement of religious leaders and
opinion leaders.
3.
Meditation
4.
Yoga
5.
Regular follow-up indefinitely
6.
Treat anxiety if present
7.
Treat depression if present
8.
Pharmaco therapy, disulfiram, Naltrexone
9.
Treat associated problems
10.
Continuous motivation many times yields favourable results
ROHC-WHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999: LN.-13
Care Of The Surgical Wound In An Industrial Set Up
DR. FRED SIMON OOMMEN,
Bangalore - 560 017.
Dy. Chief Of Medical Services, H.A.L. Hospital,
WOUND HEALING is the pride of surgeon.
Healing means
replacement of destroyed tissues by living tissues. Eventhough the principle
of wound healing is constant, this lecture would highlight the need to
concentrate on THE WOUND.
Wounds may be caused by.
1. Trauma
2. Physical, chemical and microbial agents
3. Ischemia
In the context of wound healing TWO terms should be understood
1.
Regeneration - Which means replacement of lost tissue by tissue similar
in type.
This is not "reconstitution" which means co-ordinated
regeneration of several types of lost tissues.
1.
Repair - Replacement of lost tissue by granulation tissue, followed by
fibrosis and scar tissue formation.
Types Of Wounds
1.
2.
3.
3.
Incised
Lacerated
Penetrating
Crushed
Mechanisms Involved In Wound Healing
1. Inflammation
2. Wound contracture
3.
Epithelialisation
4. Granulation tissue formation
Causes Of Wound Contraction
1. Removal of fluid
2. Contraction of collagen
3. Contraction of granulation tissue
2
Care Of The Surgical Wound In An Industrial Set Up
Factors Inhibiting Wound Contraction
1.
2.
3.
4.
5.
Corticosteroid administration
Bums - delays wound contraction
Immediate skin grafting prevents wound contraction
Irradiation - delays wound healing
Cytotoxic agents like vinblastine and trocinate, colchicine inhibit/delay
wound contraction
Factors That Influence The Tensile Strength Of The Wound
1.
2.
3.
4.
Direction of the wound
Pull of underlying muscle
Previous wound
Abdominal binder
Factors Affecting Granulation Tissue Formation
1. Cortisone administration
2. Scurvy
3. Protein stan/ation
Complications Of Wound Healing
1.
2.
3.
4.
5.
Implantation cysts
Painful Scars
Cicatrization and deformities
Keloid formation
Neoplasia
Factors Influencing Wound Healing
General factors
Age
Nutrition
Hormones
Anaemia
Uraemia
Jaundice
Diabetes Mellitus
Blood dyscrasias
Malignancy
Cytotoxic drugs
Local factors
Position of skin wound
Blood supply
Tension
Infection
Movement
Exposure to Ionizing Radiation
Foreign bodies
Adhesion to bony surface
Necrosis
Lymph drainage
Ultra Violet rays/light
Faulty technique of wound closure
3
Care Of The Surgical Wound In An Industrial Set Up
Principles Of Wound Management
1.
2.
3.
4.
5.
6.
4.
Classification of wound
Convert dirty wound to a clean wound
Role of thorough debridement
Role of delayed primary suturing
Role of dressings of wound
Role of Hyperbaric Oxygen therapy
Role of drainage of wounds
Conclusion
Providence triumphs over vallor.
Be gentle to tissues.
ROHC-WHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999: LN.-14
Veterinary Zoonosis
DR. RAGHAVAN
Professor and Head, Department of Microbiology, Veterinary College,
University of Agricultural Science, Bangalore - 560 024.
Right from earlier times it had become apparent that man shared
infections in common with animal species he was associated with Hippocrates of
(5th Century B.C.) emphasized the role of environment in preservation of human
health. As early as 116 B.C. Marcus Terrentius Verro suggested that marshy
lands maintained minute creatures which caused serious diseases in human
habitation. It is quite interesting that most of the earlier suggestions of
relationships between human health and animals were part of folk lore or
religious practice. Such an awareness resulted in early man identifying specific
disease in sentinel animal species and take appropriate measures to keep
away from them or sacrifice such animals to avoid epidemics. Now we know that
these earlier episodes cannot be ignored as blind followings and such practices
were to keep the human species away from diseases communicable from
animals which were dwelling close to him. Such diseases are designated as
"Zoonotic" and the science dealing with it as "Zoonosis".
The World Health Organization defines Zoonoses as "Those diseases and
infections which are naturally transmitted between vertebrate animals and man".
The probability of disease transmission from animals to human is influenced by
several factors, such as:
1.
2.
3.
4.
5.
Socio-economic
Ecological
Contact with companion animals
Stocking density of animals and disease mediators
Human behaviour and his food habits.
Based on maintenance cycle, of zoonoses in nature, Schwabe (1984) has
identified four groups:
1.
2.
3.
4.
Direct Zoonoses: which can spread by a single vertebrate species
either by direct contact or through a mechanical vector.
Cyclo Zoonoses: where the infection is maintained by more than one
vertebrate species.
Meta Zoonoses: in which the cycle involves both vertebrate and
invertebrate hosts.
Sapro Zoonoses: which depend on in animate development sites as well
as vertebrate hosts.
2
Veterinary Zoonosis
Any disease that comes within the ambit of zoonoses has five
components.
1.
The agent:
A parasite adapted to a lower vertebrate host with a
potential to infect human is a zoonotic disease in real sense. On the
contrary if the agent has normally a broad host spectrum including man, it
cannot be termed as a zoonotic.
2.
Reservoir host: This component is usually a lower vertebrate in which the
agent naturally occurs without overt manifestations of the disease.
Generally a number of related species of vertebrates can serve as
maintenance hosts to a given parasite. Yet it is seen only a few species of
animals are preferred in which the intensity of infection of a particular agent
is very high rendering them as the potential disseminators.
3.
Intermediate host and vector: This component is not mandatory for all
zoonotic diseases. It is essential for certain agents wherein a specific
developmental stage of the agent takes place. This aspect therefore
plays a very significant role for disease communication to man.
4.
Potential host: Invariably, this is man. Man is not a natural host in most
zoonotic diseases. But is susceptible. Audy (1965) prefers to call human
as "Species at risk"as he exposes himself to the agent by intruding into
the ecological niche of the maintenance host. This "risk" is brought about
by the activities of man himself such as religious considerations; social
practices;food
habits; socio-economic status;
recreational
and
professional hazards.
5.
Environment:
Zoonoses are associated with specific reservoirs and
often with specific vectors. The habitat of these, in turn, are associated
with specific type of localities which fulfill the requirements of these two
components. When two types of environmental requirements overlap ,
thedisease agent circulates between the two more or less restricted
localities termed as "nidus". When man enters the nidus of a disease and
disturbs it, he is likely to acquire the disease.
M^n disturbs the nidus by activities sucf] as
cultivation, animal husbandry, habitaion and settlement,
consequences of these activities are:
1. Simplification of existing ecosystem
2. Creation of edge effect
defpro^tjpn,
The
general
3
Veterinary Zoonosis
1.
Simplification of ecosystem: Human activities lead to destruction of
vegetation thereby simplifying the original ecosystem hitherto a rich and
stable system that evolved over a long period of time. The consequences
of such simplification are:
Introduction of newer species to the original ecosystem.
Uneven distribution of the existing species.
Fluctuation in population of animals and plants
utilization
2.
due
to
human
Edge effect: When two types of contrasting ecosystems occur side by
side an edge effect is experience. This immensely influences the natural
nidus of infection because it frequently encourages the exchange of the
agents between maintenance hosts and the susceptible hosts which
would otherwise hardly ever takeplace.
The edge effect gives an opportunity for wild vertebrates to mix with
domestic vertebrates helping free exchange of agents as well. When these
animals enter human habitation, pathogen also have an access to man.
The edge effect will allow some species to take advantage of biocenose for
one purpose and the other for another purpose.
In this context it is pertinent to point out that arthropods play a major role
as mediators of disease and a long list is available now which have been
identified as exclusively transmitted by them. All these diseases are placed
under the group Meta Zoonoses. The transmission of pathogens by vectors is
profoundly influenced by a number of parameters like vector density; population
density of the host; environment; spectrum of pathogen susceptibility of the
vector; geographic distribution of specific species and subspecies of the
vector. This knowledge will immensely help in designing strategies for their
control.
The basic principles of Zoonoses control and prevention are focused
upon breaking the chain of transmission at its epidemiologiclly weakest link.
They involve:
1.
2.
3.
Reservoir neutralization
Reducing contact potential to the host
Increasing host resistance.
Most of the Zoonoses had their origins in the feral species without
regard to the presence or absence of man. To become a Zoonoses, the agent
had to gain access to humans by integrated cycles of transmission such as :
4
Veterinary Zoonosis
Sylvatic-human cycle
Sylvatic-domestic cycle
Sylvatic-domestic-human cycle
From this it is obvious that the Zoonotic agent reaches man directly
from a sylvatic cycle or indirectly through a domestic species. Once it reaches
man it is invariably a dead-end.
Resen/oir neutralization can be achieved by test and disposal, mass
therapy or by environmental manipulation where in the vicinity around the
reservoir as decontaminated.
The contact potential can be reduced by isolation, quarantining,
population reduction of mediators. Stress reduction, chemotherapy or
immunization are some of the other options available for increasing host
resistance.
To achieve these goals a proper understanding of the disease, their
cycles in nature, modes of their transmission, appropriate steps of containing
them are essential.
ROHC-WHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999: LN.-15
Occupational Health Problems among Poultry Personnel
Dr. R.N. SRINIVASA GOWDA
Director, Institute of Animal Health and Veterinary Biologicals, Hebbal,
Bangalore - 560 024.
Poultry farming which were a backyard and a subsidiary occupation has
now become a highly commercialized agri business. It has taken an industrial
proposition world over. Currently, India stands fifth country in egg production and
2oth in broiler production, contributing a sum of Rs. 65 million to the GDP of our
country. This profession provides direct employment for more than 1.0 Million and
indirect employment to more than 1-3 million people in the country. The working
personnel of poultry directly or indirectly exposed too many health hazards in this
industry and the magnitude has not been assessed properly. Therefore an
attempt has been made to enlist health-related problems among poultry workers
in this paper. The poultry personnel include workers supervisors, managers,
veterinarians and laboratory workers.
The occupational health problems of poultry workers could be classified as
those problems arising from physical, chemical and biological hazards.
Physical Hazards
These include external injuries arising from fencing barbed wires, building
materials and from machines used in day to day work and electric shock and
thermal bums etc. Feed mill workers often suffer from fatal accidents and electric
shocks besides inhalation of air borne physical dust particles, dried fecal matter,
feed particles, fragments of skin and feathers from the dust of varying particle
sizes. Dobie 1964 has reported the amount of air borne dust in poultry house.
According to him, the 24-hr. dust collected in 100 c ft. is 54 grams in cage system
and 4 times greater in deep litter. Excessive dust level damages the lung
macrophage system.
Table: 1 Percentage of suspended particulate matter and itssize in poultry
sheds
4
......
% age distribution
Size of the dust particle
100
0.5 p.m
1.0 nm
2.0 pm
5.0 pm
10.0 pm
3.2
2.5
0.4
0.07
2
Occupational Health Problems among Poultry Personnel
Allergic alveolitis
Allergic alveolitis is also called hypersensitive pneumonitis, Parakeet dander,
pneumoconiosis and pigeon lung disease.
It occurs in people who are
hypersensitive to feathers, feather dust and fecal material. Signs occur within two
years but often takes as long as 10-20 year with continuous exposure.
It may occur in acute or chronic form. The acute form occurs within 4-8
hours of inhalation of high level of feathers, feather dust and fecal matter. Cough,
dyspnoea, chills and fever occur. If exposure is topped at this time, no treatment
is necessary and signs will disappear. The sub-acute form results from long term
exposure. A dry cough and progressive breathing difficulty occur. This form may
also be reversed if continuous exposure is stopped. If continued, it leads to a
non-reversible chronic form of alveolitis with severe dyspnoea, dry cough and
weight loss.
Allergic alveolitis decreases lung capacity and causes diffusion of air
through the alveoli of the lungs.
A high degree of biosecurity, including cleaning of poultry houses, cages,
avoidance of overcrowding, providing good ventilation or use of air purification
system helps in containment of this problem.
The other pollutants arising from poultry house includes a variety of dusts
borne microorganisms such as staphylococcal and streptococcal organisms
derived mainly from resident flora of skin epithelium. Aerobic spore forming and
colliform bacteria arise from litter and feed dust. Henry and Hansen 1964 obtained
20,000 to 80, 00,000 E. coli organisms in a gram of dust from the bird level.
Aspergillus fungal spores that arise from litter material as well as grain material
often cause respiratory mycosis in poultry attendants.
Table - 2:
The concentration of air borne bacteria in different poultry
housing systems
Housing System
Cone, of coliform bacteria/liter of air
Deep litter system
Cage system
132 -17,000
1000 -10,000
Source: Muller and Weiser 1987.
Noxious gases
In modem environmentally controlled (EC) poultry sheds there is always a
problem of noxious gases. The main gases are ammonia, carbon-di-oxide,
carbon monoxide, methane and hydrogen sulfide. All these gases originate from
wet litter problem.
3
Occupational Health Problems among Poultry Personnel
Ammonia content of above 20 PPM is known to cause local irritation in the
mucous membranes of the respiratory tract and sinuses, resulting in inflammation,
air saculitis and respiratory distress. This in turn leads to impair feed conversion
efficiency of the birds resulting in poor growth. Ammonia content of over 50 PPM
causes severe kerato conjunctivitis, watery eyes and blindness.
During wet conditions when the moisture contents of the litter is over 30%,
Ammonia content is often shot up by 10-15%. This ammonia at higher levels
induces pungent sensation and eye irritation to the personnel working in such
houses. The minimum requirement for air composition should be as follows:
Oxygen
Carbon dioxide
Carbon monoxide
Ammonia
Hydrogen sulfide
over
under
under
under
under
16%
0.3%
0.004%
0.002%
0.0005%
These gases are interrelated because of the bird’s physiological responds
as oxygen content decreases and carbon dioxide increases during metabolic
processes. Similarly microorganisms leading to ammonia and hydrogen sulfide
accumulation in the air break down bird’s droppings.
Chemical hazards
There are several chemical agents, which are used in poultry farming.
These include use of many nutrients in formulation of balanced feed. For e.g.
amino acid especially methionine, lysine etc., use of disinfectants and their
residues in meat and meat products and egg. Feed additives such as growth
promoting hormones antibiotics etc. Residues of antibiotics in poultry meat may
occur if withdrawing times are not adhered to. Allergic reaction in many persons
may occur to penicillin, sulfonamides, neomycin, Tylosin, tiamutin and this
reaction is not dose dependent. Extremely small doses are only required to elicit
reaction.
There are two types of reaction in human health, dermal allergies can
occur while mixing of these additives in feed by bear hands and secondly transfer
of antibiotic resistance from bird to humans through residual effect in meat, meat
products and eggs.
4
Occupational Health Problems among Poultry Personnel
Table 3: Environmental impact of some antibacterial drugs (adopted from
Anonymous, 1976)
Drug
Chlortetracycline
Oxytetracycline
Penicillin
Sulfonamide
Streptomycin
Neomycin
Bacitracin
Tylosin
Viginamycin
Lincomycin
Erythromycin
Monensin
Avoparacin
Oral doses
excreted % age
40-75
40-75
?
upto 7C
upto 100
95
95
30-76
?
100
High
35-75
High
Fate in the environment
Half life
Accumula
tion in days
>20
>20
<7
>20
7
4-10
High
High
Low
Moderate
Moderate
Low
Low
?
?
7
20
Low
Low
Moderate
Low
Low
?
?
10-70
?
Drug resistant
Non-enteric
bacteria
+
+
+
+
+
+
+
0
0/+
+
+
0/+
?
Bio Hazards
Intensive poultry farming have formidable potential for waster production and
its pollution. Bacterial, viral and parasitical pathogens can occur with fecal wastes
of birds. The bacterial pathogens that are of particular concern in poultry waste
are salmonella, E. Goli and chlamydia.
The survival times of salmonella spp. in the farm animal waste has been
estimated at 200-300, 90-200 and 5-25 days in liquid manure of cattle, pigs and
poultry respectively. The salmonella organisms could be isolated from soils for 8
months after application of contaminated piggery and poultry waste.
Spread of enteric bacteria in the environment especially E.coli is highly
successful bacteria excreted through poultry that and pass through fecal matter.
Pollution occurs in pastures, streams and rivers. From litter/fecal contamination
and from which the organisms may infect and colonize in other animals and
humans. Farmers, abattoir workers, butchers will get contact with enteric bacteria
especially antibiotic resistant E.coli and enterobacteriae especially Salmonella.
A variety of disease causing agents may affect the farmers through
zoonoses (Diseases transmissible from poultry to man).
Young children, elderly adults and immuno-compromised individuals are at
great risk of being infected by zoonotic diseases. Immune-compromised
5
Occupational Health Problems among Poultry Personnel
individuals include those infected with the Human immuno-deficiency virus (HIV),
patients taking immunosuppressive drugs, cancer patients and the unborn fetus.
Although the list of zoonotic diseases involving birds is somewhat
extensive, the following diseases are of reasonable significance.
Chlamydiosis (Psittacosis or parrot fever)
Salmonellosis
Campylobacteriosis
Newcastle disease
Mycobacteriosis
Influenza
Giardia and
Cryptosporidiosis.
Chlamydiosis
Psittacosis is a common disease of wild birds throughout the world, caused
by Chlamydia psittaci. The birds are often exposed to infection and the organism
settles down in spleen without causing any effects. These birds pass Chlamydia
intermittently in the feces and transmit to their young ones at the next breeding
season. Such latent infection can be activated by stress. Chlamydia is a disease
of Psittacine birds (eg.Parrots, Cockatoos, Budgerigars). A wide variety of other
species can be affected (finchers, sparrows, pigeons and waterfowls) and these
spread infection to commercial flocks.
Duck farms established nearer to
waterfowl migrating areas can infect ducks and farm employees and workers in
poultry processing plants where ducks are killed.
Chlamydia psittaci can survive in poultry litter for 2-8 months and litter
material is the potent source of contamination and infection occurs by
inhalation. Mites can also harbor Chlamydia for three or more months.
In agricultural enterprises those predominantly at risk are poultry farmers
and their families, Veterinarians and employees in poultry processing plants and
diagnostic laboratories. Hazardous aerosols are created from dried fecal material,
liberated down and feathers during killing, breeding, de-feathering and
eviscerating process of poultry. Similarly aerosols arise during necropsy of dead
birds and veterinarians will be at risk.
Disease in humans occurs as an acute generalized infection of variable
severity, after an incubation period of 4-15 days resembling mild influenza with
headaches and myalgia, before fever develops and symptoms become more
acute. Person to person spread is possible but rare. Fever, headache, muscle
pain, photophobia are common findings.
Control of dust, high degree of
sanitation, preventing contact between free living and domesticated birds,
management induced stress in the birds must be minimized.
Avoiding
overcrowding, stress during transportation between farms and abattoirs and
6
Occupational Health Problems among Poultry Personnel
Depriving them of food and water can increase fecal excretion of Chlamydia and
precipitate clinical disease. Infected flocks should be quarantined. High doses of
tetracycline’s helps in suppressing the infection but not always eliminate. Poultry
industry employees must remain aware that Chlamydia is shed intermittently in the
faces of normal birds so that the infection can be transmitted without necessarily
having contact with obviously diseased birds.
Regular disinfection of poultry
houses, abattoirs and prevention of aerosol infection are important in reducing
human exposure.
Salmonellosis (Food poisoning, enteric paratyphoid)
Poultry products are important sources for humans since the intestine may
rupture when the pluck is removed from the carcass during processing, liberating
gut contents into the thoracic and abdominal cavities. Stuffing introduced into
interior becomes contaminated with Salmonella organisms.
The farming community has an important responsibility to limit the
incidence of salmonellosis. In the first place, birds should be raised under good
management and nutritional conditions so as to control the occurrence of infection
diseases so that birds sent to market are in good health.
Li steria monocytogenes
It is a ubiquitous bacterium found in the intestinal tract of human and
animals including variety of vertebrates, and in soil and water in which it can
survive for months to years (Mitscheriich and Martin, 1984). Occupational risk of
acquiring listeriosis is greater among persons handling poultry.
Listeriosis has similar manifestations in humans and animals, with
meningioencephalitis or abortion, prenatal mortality of off sprint and septicemia as
prominent syndromes.
Mode of Spread:
Contaminated litter
Manure to grow vegetables
Soil contamination
Eating raw vegetables
Listeriosis
Compylobacteriosis
This disease is caused by Compylobacter jejuni, a Gram -ve, non-spore
forming, motile rod. This organism has been incriminated as a cause of diarrhea,
often exclusive in onset, accompanied by acute abdominal pain. It is a common
bacteria of gut of birds; claims have been made that human infection is usully
acquired from dressed poultry.
/
7
Occupational Health Problems among Poultry Personnel
Avian Tuberculosis: (Mycobacteriosis)
Avian tuberculosis is caused by M. avium; M.intracellave and
M.genovense, M.tuberculosis and M.bovis have been isolated in birds. These
organisms occur throughout the world in the waterfowls, psittasins, pesserines,
columbiformis and raptores.
Humans are more commonly infected with M.tuberculosis and M.bovis.
Immunocompromised people, (ex.HIV infected) those on chemotherapy, the
elderly and children are at risk.
Ingestion and inhalation of aerosolized infectious organisms from faces
transmit avian tuberculosis.
In adult humans, tuberculosis frequently affects lungs, producing
respiratory signs. In young children the cervical lymph nodes are often involved
and in HIV patients often have disseminated form. People who are infected with
human tuberculosis should not own birds, since people may serve as source of
infection to their pet birds.
Newcastle Disease (ND)
ND is a viral disease of domestic and wild birds predominantly transmitted
by inhalation and with a wide spectrum of pathogenicity.
Spread through
ingestion of infective material is also possible. Considering the wide spread
nature of ND in poultry, human infections are relatively less. Those at risk are
poultry farmers and Veterinarians and laboratory workers. Human infection with
virulent NDV develops as conjunctivitis, usually with enlargement of precrural
lymph nodes. Fever of variable degrees with headache and lethargy develop in a
minority of cases. Infection runs a short course resolving without residual
complications with in 2-3 weeks.
Avian Influenza
The so called bird flu a synonym of avian influenza or Fowl plague an
infectious syndrome caused by influenza type A virus belonging to family of
Orthomyxoviridae.
It is a pleomorphic RNA virus having three antigenically
distinct types, A, B, and C types. Type A is causing avian influenza, whereas B
and C are typically found in humans. Type A can also jump into other spp. Such
as swine, horse, mink, seals, whales and human beings.
A strain was previously known to infect only birds was isolated in
Hongkong from a specimen collected from a 3 year old child who died in May
1997, of respiratory failure. The virus was identified as influenza Type-A (H5N1).
8
Occupational Health Problems among Poultry Personnel
The influenza A- (H5N1) virus is known to infect ducks, chickens and other birds
but had not previously been isolated from humans.
Between late November and 30th 1997, a total of 13 confirmed and 6
suspected H5N1 influenza cases have been identified. The age group of the
confirmed cases ranged from 1 to 54 years. However seven of 13 confirmed
cases are 5 years of age or younger.
Blood samples collected from family members of cases, nursing staff and
other contacts, antibody to influenza A (H5N1) virus was found in nine blood
samples out of 502 tested in May 1997 in Honkong. The antibody to virus was
detected mainly among poultry workers and people directly exposed to virus. As
a precautionary measure, the Honkong authorities have destroyed 1.3 million
chickens between 30-31 Dec.1997, in order to eliminate the potential risk of
transmission of the infection from poultry.
Ringworm
Ringworm is a common skin infection of animals and birds. Only
Trichophyton verrucosum and T.mentagrophytis cause ringworm infection in
humans. The condition is manifested as acute inflammatory reaction spreading
lesion usually on the face of persons of all ages who are handling contaminated
poultry.
Ectoparasites
Many ectoparasites are capable of affecting humans, either by direct
contact or from environment. Stick fast fleas (Echidnophaga gallinaceae) of
poultry attach around waist in the hair and around neck and legs causing
considerable irritation and hypersensitivity.
Omithonyssus spp.redmite of poultry also cause nuisance in human
beings.
Conclusion:
In poultry enterprise those, predominantly at risk are poultry farmers and
their families, veterinarians, employees in the poultry processing plants and
diagnostic laboratories. The dust and microbiological agents are always found to
be there in poultry houses and both can therefore affect the health of man and
birds. The respiratory system is mainly affected.
Chemical and mechanical
irritations and allergic reactions can develop. The nuisance of files and odor can
cause unpleasant situation reduced appetite leading to nausea and vomiting.
Ammonia is the main cause of irritation to the mucus membrane and inhibits
cytochrome oxidase depressing cell metobolism and affecting the central nervous
9
Occupational Health Problems among Poultry Personnel
functions. The egg and meat products carrying residues of antibiotics may cause
development of resistant strains of bacteria. Therefore careful selection and
application of drugs for growth promotion and therapy is necessary. Use of
biotechnological methods to control biohazards such as Salmonella, E.coli, and
Campylobacter etc. has to be considered for future poultry farming.
References
1.
Anderson,D.P., Beard, C.W. and Hanson, R.P. (1964)
Influence of poultry house dust, ammonia and carbon dioxide on the
resistance of chicken to Newcastle virus.
Avian Diseases, 10, 369-379.
2.
Harry, E.G. (1964)
The survival of E.coli in dust of poultry houses.
Vet.Record. 76, 466-470.
3.
Johnson, J.E. (1966)
Farmer's lung in Maryland.
Ann.Intern.Med.64, 860-872.
4.
Koon, J. and Howes, J.FL (1963)
Poultry dust: Origin and composition.
Agric.Eng. 44, 608-609.
5.
Reed,C.E., Sisman, A. and Barber, FLA. (1965).
Pigeon breeder's lung, a newly observed interstitial pulmonary disease.
J.Am.Med.Assn. 193, 261-265.
/
ROHOWHO Trg. Prog. On Occ. Health In Agricultural Sector, Feb. 8-12,1999: LN.-17
Health Hazards Among Small Laboratory Animal Workers
Dr. B.R. SRINATH
Principal Research Scientist, Central Animal Facility, Indian Institute of Science,
Bangalore - 560 012.
Use of laboratory animals in biomedical research, teaching, demonstration
and drug testing has increased tremendously and thereby all the research
workers, laboratory workers, technicians, animal handlers are exposed to various
health hazards in animal house environment. This paper attempts to discuss all
aspects of health safety in the animal facility and laboratory.
Physical Hazards (Direct Environmental Hazards)
First and foremost hazards directly exposed to will be the work
environment where the persons have to work in the presence of animals.
Whatever is the type of air-conditioning system to maintain the temperature and
proper adoption of air changes, there is some amount of effect on workers due to
exposure to animals as well as their excreta which creates enough odour, unless
the bedding of the animals are changed frequently along with excreta. Otherwise,
there is bound to be increase in the humidity as well as ammonia concentration
which will affect the workers when it exceeds the permissible limit of 40 PPM. The
effect of this will be seen in persons as symptoms of irritation of eye and nasal
mucosa. This could be reduced by frequent cleaning and health sanitation
procedures.
In case of emergency washing of the eyes with cold water and application
of eye drops will help in controlling eye irritation. So also usage of filter masks
could reduce nasal irritation.
Injuries From Animals
In working with animals, scientific workers and technicians come
across bites and scratches from rats, mice, rabbits and guinea pigs which can
be treated as a normal wound and precaution could be taken by giving a shot of
anti tetanus vaccine. However in case of bites from dogs and monkeys it
should be viewed more seriously. Monkey and dog bites often cause serious
wounds which needs to be stitched up under sterile conditions and needs
proper care which includes anti tetanus and anti rabies vaccine.
It is advisable to have all the staff immunised with anti rabies and
hepatitis B vaccine every year. When the monkeys are caught from endemic
2
Health Hazards Among Small Laboratory Animal Workers
areas of herpes B virus and Kyasanoor Forest Diseases special care has to be
taken to vaccinate persons against those diseases also.
With reference to maintenance of dogs, one should take care about the
effect of continuous barking on the workers psychologically. There is also a fear
complex associated with anxiety among workers handling the dogs. This can be
avoided by adopting a work regimen of frequently rotating the workers between
different facilities of the animal house.
General Physical Hazards
In an animal colony doing experimentation there is always some
minor technical operations and surgical operations.
In such situations,
handling of needles for injections
and surgical scalpels may
cause
accidental injuries. If the same needle and scalpel are used for animals such
wounds should be treated separately.
History of such animals and their
symptoms need to be obtained. It is therefore better that protective gloves are
used in all situations.
During some experiments with animals, aerosols are used for disinfecting
the animal cages and animal rooms. The concentration of the aerosols used
like formalin should be carefully monitored. A wash with mild disinfectant aerosol
is mandatory. A period of time is to be allowed after aerosol disinfection
before allowing the personnel to enter the rooms in such situations.
Other aerosols are the animal dust, fur and hair , which can cause
irritation to the eye and nasal mucosa from the animals which may later on
develop into allergic reactions. In such cases the personnel should be skin
tested to allergies against each of the species handled prior to commencing
the work and wherever possible avoid or minimse contact by use of protective
clothing. Even the odour of urine and faeces may be sometimes allergic to the
workers, which can be avoided by using protective masks. Smoking in the
vicinity of animal rooms causes the inhalation of allergic dust, fur, hair and
other odours. This should be avoided.
Biological Hazards
All animals must be regarded as potential sources of naturally
transmitting infections, which are called zoonotic diseases.
Though this risk
varies widely with the class and species of animals involved, an animal which
is more closely related with human has greater likelihood of transferring the
disease to man. It is for this special reason that special precaution has long
been advocated for handling non-human primates.
3
Health Hazards Among Small Laboratory Animal Workers
While most of the infectious agents show a considerable degree
of species specificity, they may also vary from time to time widely in their
virulence and their capacity to break through species barrier. These infections,
which are not commonly considered hazardous to human beings, may
sporadically affect susceptible persons when come in contact with animals.
Numerous
pathogenic microorganisms such
as those responsible for
tuberculosis, brucellosis, rabies, tetanus may be transmissible to man. Infections
such as ringworm are particularly wide spread often in a subclincal state.
The life cycle of a causative organism implicated in a number of indirect
infections transmittable to man through one or more intermediate hosts are
toxoplasmosis, taeniasis, tularaemia and vesicular stomatitis. In case of
cold-blooded animals like tortoises with salmonella infections can cause human
health hazard.
The transmission of infections from animal to man can generally be
avoided through proper veterinary care and adherence to careful experimental
procedures. Quarantining of animals before they are introduced into the colony
and thorough
examination
of
animals
including
the microbiological,
parasitological and viral monitoring would go a long way in ensuring the safety of
workers working with animals.
It is important to ensure that animal technicians and workers are healthy
and have normal resistance to infection. Particular attention should be given to
allergic reaction of the worker to animal dust, fur, waste and excreta.
Bio Hazard identification And Hazard Protection
Diseases can be transmitted from man to animals and animals to man.
The former could be avoided by carefully monitoring the animal workers' health.
If the worker is ill, the medical officer concerned should decide whether or not
the person should continue to work with animals. Similarly the responsible
veterinarian or supervisor must decide whether or not to continue the
utilisation of worker handling the animals.
Personnel cleanliness is an important barrier to infection. Washing of
hands after handling animals will reduce the risk of disease spreading and self
infection. To facilitate this each animal room should be provided with small
hand sink, soap and paper towels. In any event, the working staff should be
continuously reminded of this simple but significant precaution.
Smoking, eating and drinking should not be allowed in animal holding
rooms and other areas in which pathogenic microorganisms are being handled.
No person with open wounds or an eczematous condition should be allowed to
work where he is likely to come in contact with pathogenic microorganism
unless he has sufficient protective clothing and gloves.
4
Health Hazards Among Small Laboratory Animal Workers
Laboratory clothing worn in risk areas should be autoclaved before
they are washed. Shoes should have disposable covers in barrier and high
risk areas.
If highly infective animals and agents are to be used, the experimental
animals should be isolated. Ventilated cabinets or cages should be sterilised
(Horsfal and Biolaminar flow units) and all exhausted air should be burnt out or
filtered.s
When animals are injected with pathogenic material, the animal worker
should wear protective gloves. Gloves should be worn while feeding, watering
and removing the infected animals.
Necroscopy
and autopsy of animals infected
with contagious
organisms should be carried out in ventilated safety cabinet. Necroscopy
material for disposal should be sealed in plastic bags which are sealed, properly
labeled and incinerated.
Chemical Hazards
Injuries from chemicals can be avoided by treating all chemicals with
care and by knowing their properties and adhering to the accepted safety
procedures for handling that type of substance. In assessing a chemical, the
following points should be noted:
a.
b.
c.
d.
e.
f.
gh.
Name
Physical state (solid, liquid, gas)
Toxicity (acute or chronic), by injection, inhalation and absorption
Maximum permissible concentration
Vapour density (concentrations at ceiling and flooring)
Miscibility with water (antidote)
Compatibility with other chemicals
Inflammability (whether high or low) and storage condition requirements
These chemicals should not be stored with animal feed. Volatile liquids
used as anaesthetics or for euthanasia and other toxic and volatile materials
should be stored in separate cool, well ventilated and at specially designated no
smoking areas and away from fire hazard zones. .
Animal house wastes which cannot be rapidly disposed off should be
stored in a cold storage area provided forthat purpose. Such areas must be
vemin free, easily cleaned and disinfected as well as being physically
separated from the other storage facilities. The waste storage areas should
be located so that the wastes are not carried through other rooms of the facility.
5
Health Hazards Among Small Laboratory Animal Workers
National guidelines as well as local provincial laws with regard to waste
disposal should be followed.
An incinerator with controlled air system is probably the most efficient
with very low stack emission.
Radiation And Ultraviolet
Radioactive wastes present special hazards to the workers working
with these material. They should know the properties of each and should be
familiar with appropriate safe handling techniques and other regularities. The
workers and technicians working with radio active materials should be specially
trained in the radiation safety procedures.
Isotope treated animals may pass radioactive material in their
excrement and also exhale radioactive vapours. Personnel should take
special precaution to avoid animal scratches or bites. Complete records
should be kept throughout the final disposition of these animals.
The radiation areas should be separated from other animal housing
and work areas. Isotope rooms should be covered with non porous material
which can be replaced if contaminated where extreme precaution are needed
for disposal. Water proof paper with gummed backing may be applied to walls,
floors, benche tops and discarded after use with due precautions.
The eye and skin are critical areas for ultra violet exposures. The eye,
in particular, can be seriously injured if U.V. lights are accidentally switched on.
The workers can use wrap around safety glasses.
The maximum
intensities which could be for sensitive person ranges from 0.1 - 0.5 milli watt per
sft.
Precautions To Be Taken By Animal Workers
1.
Use rubber gloves while handling animals,
tissues.
2.
Require routine use of lab. coats and overalls
animal quarters.
3.
Carry out prolonged procedures for animals under a ventilating hood.
animal wastes and animal
issued specifically for
6
Health Hazards Among Small Laboratory Animal Workers
4.
Keep oral and injectable anti histamines for urticaria and
rhinoconjunctivitis, adrenergic compounds such as ephedrin for asthma.
5.
Work involving exposure to hazardous microorganism may require prior
immunisation of staff if a vaccine is available. Serological testing and
banking of a reference serum sample from all personnel working in the
animal facility is an advisable procedure to follow.
6.
Caution should be exercised in assigning women of child bearing status
to animal care duties that might expose them to potential or known
teratogenic agents.
Hazards Of Laboratory Animal Workers:
Examples of cross infection in laboratory animals
1.
Rat
Mice-* Man:
Dogs-*Rodents-* Man
Cats -* Pigs -* Man
Guinea pigs-* cats-* Man
Dogs -* Monkeys-* Man
2.
Salmonellosis and respiratory diseases.
Respiratory diseases, cestodes.
Respiratory infections, skin infection and
tetanus.
Pseudotuberculosis.
Ringworm (M. camis)
Routes Of Infection:
1.
2.
3.
4.
5.
6.
7.
8.
Bite: Direct inoculation often deep
Scratch: Often introduces dirt into wound.
Existing wounds: Accidental inoculation by contact
Aerosol by infected saliva or other body fluids via lungs, eyes etc.,
Mammal infection via mouth from contaminated fingers
Accidents involving skin punctures from soiled needles etc.
Anthropod vector (ectoparasites or substitute hosts)
Inhalation of contaminated dust or dried fecal material
3. Mice And Rats:
Diseases transmissible to man from rats and mice:
Murine pneumonitis virus
Lymphocytic choreomeningitis virus
Pastuerella multoceda (septica)
Respiratory pyrexia
Respiratory pyrexia
Respiratory pyrexia
Salmonella Typhimirium
Enteritis
Trychophyton metagraphitis
Ring worm
7
Health Hazards Among Small Laboratory Animal Workers
Streptobacillus monilliformis
Leptospira icterohaemorrhagica
Spirillum minus
4.
Dogs
Diseases transmittable from dogs to human:
Toxacara canis
Ancylostoma canninum
Echinococcus granulosus
Toxiplama Gondii
Microsporum canis
Leptospira canicola
5.
Arthritis
Leptospirosis, infectious jaundice
Rat bite fever
Canine roundworm
canine hookworm
Tapeworm (leads to hydatid cyst)
Ring worm
Ringworm
Leptospirosis, infectious jundice
Diseases Tranmitted From Monkeys To Man
Scrub typhus, scabies, pulmonary
ascariasis
Ectoparasites
mites
Endoparasites
Schistosoma sp.
flukes
Tapeworms
Roundworms Hookworms and filariae
Protozoal diseases
1. Intestinal
2. Blood bome
Entamoeba (amoebic dysentry)
Trypanasomes, sporozoa(malaria), toxoplasma
Bacterial diseases
1. Enteric
2. Blood borne
3. Respiratory
Shigella species (bacillary dysentry)
Spirochaetes
Tuberculosis
Viruses
1. Normally occurring non-pathogenic types in apes and monkeys transmitted
to human become fatal. Eg: Yellow fever
Herpes B. simiae
Lassa fever
8
Health Hazards Among Small Laboratory Animal Workers
5. Safety Philosophy
a.
b.
c.
d.
e.
f.
g.
h.
Aim for good accommodation and husbandry
Beware of potential hazards
Report all incidents
Prohibitions are applied rigidly irrespective of the status of the person
Firm and discreet policing of general procedures
Regular review of procedures
Designate a safety officer with full authority to act
In-house training at appropriate levels is a must
ROHC-WHO Trg. Prog. OnOcc. Health in Agricultural Sector, Feb. 8-12,1999: LN.-18
Causation of Work Environment And Chemically Induced
Cardiac Diseases
DR. U.B. KHANOLKAR, DR. A. GORI
Wockhardt Hospital & Heart Institute, 14, Cunningham Road, Bangalore-560 052.
Cardiovascular function is regulated to preserve two vital functions, tissue
oxygenation and normal body temperature. For example, during muscular
exercise, the oxygen supply to the working muscles must be increased, and
concurrently the increased heat generated must be dissipated. Humans are often
subjected to environmental factors that stress cardiovascular regulation severely.
Exposure to high altitude induces atmospheric hypoxia, which reduces muscular
working capacity in spite of major adaptation to preserve tissue oxygenation. In
hot environments, temperature regulation must compete with increased demand
for oxygen during exercise and here again working capacity is reduced.
Regrettably our environment is frequently contaminated with noxious substances
one of the most lethal of which is carbon monoxide.
To the patient the
cardiovascular disease adaptation to such environmental stresses as heat, cold or
the high altitude induced hypoxia becomes an even greater challenge.
Ascent to high altitude increases myocardial oxygen demand, primarily
through increased Heart Rate (HR). Such increased demand must be met by
increase in oxygen supply.
In general, this is accomplished by increasing
coronary blood flow. Within a few days HR will decrease and arterial oxygen
content will be restored by haemoconcentration. In addition, there is a shift of the
oxygen dissociation curve to the right.
In patients with stable coronary heart disease and reasonably good
exercise tolerance at sea level, exposure to high altitude is not likely to precipitate
a coronary event. The heart rate for a given level of exercise is higher but there
is no increase in ST-T changes.
Acute ascent up to 10,000 feet (3000 meters) does not result an increase
pulmonary artery pressure. Residence at the altitude will result in pulmonary
hypertension. The pulmonary artery pressure (PAP) is usually twice that at sea
level, the mean PAP ranges from 11-45 mm Hg. and during exercise may exceed
60 mm Hg. The pulmonary hypertension of high altitude is generally benign, non
progressive and reversible with descent to lower altitude.
Occasionally patients ascending to high altitude develop acute high
altitude pulmonary edema (HARE). The incidence is between 1 and 10 per
10,000 persons ascending rapidly to high altitudes above 8,000 feet (2,400
meters). Symptoms are usually seen between the second and seventh day at
such high altitudes.
The patient has undue shortness of breath, cyanosis,
tachycardia, crepitations, fatigue and non-productive cough. This is a form
2
Causation of Work Environment And Chemically Induced Cardiac Diseases
of non-cardiogenic pulmonary edema and recovery is prompt on descent to lower
altitude. The pathogenesis is uncertain. It is either due to increased permeability
of the lung vessels or increased pressure within the pulmonary vessels which
force fluid into the lungs. The consensus is that HAPE is part of the spectrum of
acute mountain sickness, with relative hypoventilation and abnormal fluid retention
as underlying factors.
Heat Stress
Humans adjust to heat stress mainly by altering the vasomotor state of the
skin to regulate heat exchange with the environment. Sweating and shivering
further modifies thermal balance.
Patients with mild CHF when exposed to heat stress can have acute
cardiovascular collapse. Heat injury in saunas can occur rapidly with no
prodromal warning. The risk is higher in-patients who are hypertensive or who are
prone to coronary insufficiency.
Cold stress
Exercise in cold environment is stressful to patients with effort angina.
The cold environment probably causes a reflex sympathetic stimulation with a
resultant increase in systolic blood pressure and a modest increase in heart rate.
This elevation of the rate of pressure product increases myocardial oxygen
demand, which is normally met by endothelial dependent coronary vasodilatation.
In-patients with coronary artery disease, there is a paradoxical decrease in
coronary blood flow because the loss of endothelial function results in unopposed
constrictive influence of sympathetic stimulation.
Exposure to noxious substances
Cartoon monoxide exposure is common, in work places close to motor
vehicle exhaust and near mal-functioning furnaces. By reducing oxygen transport
by hemoglobin and by inhibiting mitochondria metabolism, cartoon monoxide
can aggravate coronary disease. Methylene chloride, a solvent used in paint
stripping, is converted to cartoon monoxide and thus poses the same risk.
Exposure to cartoon disulfide, a chemical used in the production of rayon,
accelerates the rate of atherosclerotic plaque formation.
3
Causation of Work Environment And Chemically Induced Cardiac Diseases
Mental stress
Stress is the body's response to real or imagined events perceived or
requiring some adaptive response and or producing strain. Environmental factors
such as excitatory psycho-emotional influences may be one of the factors
responsible for the hemodynamic expression of genes responsible for
hypertension. The metabolic and physical consequences of stress can contribute
to atherosclerotic plaque rupture. Cardiac ischemia induced by mental stress
might be produced by a combination of factors, including increased myocardial
oxygen demand and reduced coronary blood flow secondary to coronary
vasospasm.
ROHC-WHO Trg. Prog. On Occ. Health Problems in Agricultural Sector, Feb. 8-12, 1999: L.N. 20
Industrial Hygiene Survey In Coir, Agarbathi And Tea
Industry
DR. V. KRISHNA MURTHY
Senior Research Officer, Regional Occupational Health Center (Southern), I.C.M.R.,
Library and Information Center Block,
Bangalore Medical College Campus,
Bangalore - 560 002.
Occupational Hazards in Coir Work
Coir is of great economic importance for India in general and Kerala State in
particular. India contributes 60% of total contribution.
Besides the huge foreign
exchange earnings coir work provides a means of sustenance for very large
population. The operations are not mechanized but conventional methods of large,
heavy looms are employed to weave the coir mats. Before the yam is spun, the
husks are retted in backwaters of the sea for a lengthy period, they are then beaten
manually to release fibbers and spun by hand operated spinning wheels to make into
ropes which will be the raw material for weaving and mattress manufacture.
The principal work processes in the coir work are:
1. Tree climbing
2. Retting
3.
Dehusking
4. Beating
5. Spinnig
6. Bleaching/smoking
7. Dyeing of yam/Stenciling of mats, rugs
8. Weaving
9. Shearing
10. Finishing (edge trimming, dipping, stitching etc.)
An environmental hygiene study in coir industries (14 small cottage coir units
where smoking, bleaching and dyeing processes of the coir yam was existing) along
with collection of environmental samples from open environment where husking and
retting processes were going on, near the sea shore was carried out.
The following parameters were studied in these coir industries:
Dust and dustiness in work environment
a)
b)
Sulfur dioxide concentration in big coir units, where sulfur was burnt in
smoking rooms.
Prevalent noise levels were monitored
c)
d)
Prevalent thermal parameters were monitored.
2
Industrial Hygiene Survey In Coir, Agarbathi And Tea Industry
Table - 1: Mean levels of dust concentration recorded in different sections in
coir industries
1.
2.
3.
4.
Section
Weaving
Shearing
Finishing
Dyeing
Total Dust pig/m3
Mean (Range)
5.17(2.50 - 6.80)
24.16 (1.28 -83.70)
3.00 ( 0.075 - 6.96)
3.94(3.16 -5.60)
Resp. Dust |ig/m3
Mean (Range)
1.91 (0.95—2.45)
2.60 (0.19-11.15)
0.30
Dust particles have an important property of adsoprtion due to their large
surface area. They can adsorb harmful gases many times their own weight
depending on the specific adsorption. Viewed in his context, the dust in the
environment of coir processing along with sulfur dioxide may have significant
influence.
The results could be summarized as under:
1. Average air bome total dust and restorable particulate concentration in most of
the sections monitored in big and small cottage coir units are found to be less
than TLV Prescribed (i.e. 10 mg/m3).
2.
Dust concentration was found maximum (24.16 mg/m3) in the Shearing
department of big coir units. In other departments total dust concentration was
not high.
3.
Average values of respirable dust also show higher levels in shearing section
(2.6 mg/m3) than weaving section (1.91 mg/m3). The maximum value recorded
for respirable dust in Shearing section is 11.15mg/m3 (Table-1).
Fuming with sulfur dioxide (SO2)in a fuming chamber bleaches mats. In most
of the factories fuming chamber is usually located very close to he shearing machine.
The sulfur dioxide concentration was monitored only in the smoking chambers of big
coir units.
Table - 2: Sulfur-dioxide concentration in different sections in Coir Industries
Total No. of
Resp. Dust jig/m3
Section
Samples
Mean (Range)
1. Shearing___________
3
5767 (2100-8000)
2. Smoking Room_____
14
2706(550-7223)
Entrance-smoke room
9
1751 (500-3334)
4. Finishing & Packing
6
2414(1666-5600)
5. Dyeing____________
2
T races______
6. Gen. Environment
10
1345(20-4000)
3
Industrial Hygiene Survey In Coir, Agarbathi And Tea Industry
It was observed that the sulfur dioxide concentration was very high inside the
smoking chambers of these units TLV prescribed for SO2 by ACGIH is 13 mg/m3).
The concentration of SO2 in the general environment was less than TLV (1.345
mg/m3).
The values near the shearer are in the range of 2.1 - 8.0 mg/m3. The
shearer not only works amidst concentrated dusty atmosphere, but also in an
atmosphere with considerable SOP levels. That may be the cause of frequent
respiratory system complaints of the shearers and other workers working in the
smoking room were complaining of irritation of the eyes, throat and nausea.
Sections like finishing, trimming, packing etc. have been classed together and
shown as ‘finishing’ in the Table-1 & 2.
The dust levels in those sections are
considerably less than those in the shearing section. However, sulfur dioxide levels
recorded in these sections are high. Dust levels though low when compared along
with high sulfur-dioxide levels indicate that the working environment may be
hazardous
The noise levels in both big and small coir unit were within the permissible
level of 90 dBA. The noise levels were monitored at shearing and weaving
departments.
The thermal parameters were recorded in different departments especially at
dyeing and bleaching sections. The WBGT values were not high and the were within
the recommended values for the work carried out in these units.
Agarbathi Industry:
Incense and fumigants represent the oldest mathod of perfume release (per,
fumum - through smoke). The perfumes are organic chemical compounds whihc
produce pleasant olfactory sensation either in the concentrated or suitably diluted
forms. The salient features of the agarbathi industry are :
a.
Units are concentrated in City of Bangalore and some other parts of
Karnataka State.
b.
The industry is less organized involving workers of all age groups. Bangalore
city has over 300 agrabathi manufacturing industries. 134 out of these
are registered under Factories Act. Over 5000 workers are engaged in this
industrry at Bangalore.
4
Industrial Hygiene Survey In Coir, Agarbathi And Tea Industry
Objectives of the study were :
1.
To assess the dust concentration in work environment at some important
workspots
2.
To enquire into general health status of workers.
A total number of 13 factories were selected for industrial hygiene (dust
monitoring) survey.
Flow chart showing the manufacturing process of agarbathies
Jigatu powder(30%) Spent wood powder(25%)
Charcoal Powder(25%)
▼
Mixed in water
Rolled on bamboo^ticks and dried
Raw sticks (Unscented)
Dipping or sprinkling
Draining aifd drying
Agarbathies
(Incense^ticks)
Packed in plastic or paper covers
Packed in pre-fabricated containers or cartons
Wrapped in visually appealing paper
Packed in wooden crates
^Transported to dealer
Results:
Table ~3:The mean levels of dust recorded in different sections
Dust:Pers. Sampling Dust: Resp. levels
Dust L.V.Sampling
Section
ug/m3___
______ pg/m3_____
ug/m3
96.16
1347.83
383.47
1. Mixing
(49.9-150.3)
(226.4-4697.3)
(170.3-517.4)
20.18
632.29
163.77
2. Rolling
(12.9-33.4)
(135.1-852.8)
(97.4-270.3)
15.94
343.32
123.54
3. Packing
(10.8-27.4)
(321.6-367.1)
(65.4-210.7)
56.90
4. G. Envi.
(47.5-110.2)
(Admn.)
5
Industrial Hygiene Survey In Coir, Agarbathi And Tea Industry
Low volume air sampling(representing background dust concentration is
work environment) method has shown comparatively lesser concentration when
compared to personal sampling method indicating subjective exposure concentration
is more. That is dust concentration in the breathing zone as a hazard is prevalent
at the work spots monitored.
However, the proportion of total respirable particulates is comparatively lesser
at all the corresponding sections. This suggests that the nature of particulates as
being larger in seize and heavier in mass; hence tend to settle down soon after
evolution during working. Of the three main sections monitored, mixing of raw
materials for making a dough is the work which liberates considerable dust particles
to which those particular workers are exposed. This operation is chiefly done by
by women.
A large varieties of organic chemicals which liberate the aroma are used
(predominently the esters, aldehydes, ketones, synthetic and natural oils like
cedar wood oil, clove oil, amir, bliss, rose oil etc.) which are the derivatives eg.
aldehydes, amyl benzoate, benzyl butyrate, methyl phenyl acetate etc., are used in
large quantities. Besides these many unknown formulations under various trade
names are also utilised. Solvents for diluting the perfumes and oils used are
dimethyl phathalate, dimethyl sulphate.
Suggestions:
Dust control measusres such as the operation to be carried out in well
ventilated areas (preferable exhaust ventilation facility) and workers be provided with
dust masks (filter pad type) as personal protective device and asked to wear while
they mix the chemicals is suggested. Hand gloves and aprons(impermeable) are
suggested to be worn when the workers are to work with the organic chemicals.
Tea Industry
India is one of the largest tea producer of tea in the world accounting for nearly 33%
of the global production.
Brief description of tea production:
The tea plant grows well only in the slopes of hills in the elevation of 1000 m
to 3000 m. It is a bushy plant about 4 feet tall and 6 ft. across. Only the tender
leaves can make a good tea. These te4nder leaves in the form of "two leaves and a
Bud" are hand plucked periodically, usually onceonce in 2 to 3 weeks. The tea
plucking is done by women. The plucking rate varies from 20 to 80 kg worker per
day but the average is about 25 kg. and the same is sent to the factories for
further processing.
6
Industrial Hygiene Survey In Coir, Agarbathi And Tea Industry
Factory work:
Withering: The tea leaves are spread on the lofts through which a current of air is
forcibly blown to reduce the moisture content of the leaves. This process lasts for
8-10 hours, and the mss is reduced by one half of the original weight.
Rolling : The whithered leaves are then fed to the rolling machine which partially
crush the leaves and twists them. The rolling is done to rupture the cells in the
leaves. Fermentation: The rolled leaves are heaped in special trays and kept in
fermentation chambers where temperature and humidity are carefully controlled,
this is an important step which determines the flavour of the tea.
Drying/Firing : The fermented leaves is quikly dried in a drier, the drier is a long
conveyor belt heated by hot air drawn from a furnace, the conveyor is so arranged
to give graded heating. The furnace is heated by burning coal, firewood or oil. The
modem furnaces are electrically heated.
Sifting: The dried tea leaves are subjected to cleaning process to eliminate
stalks which are handpicked or removed using electrostatic separators called
Fibrex machines. The cleaned tea is now graded by sieving through sieve of
different meshes. This is the sifting operation. This is a dusty operation during
which a cloud of fine tea dust called fluff arises.
Packing: The graded ted leaves are packed in aluminium foillined wooden chests
and sent to the market. Furnace operation: In addition to the above operations a
furnace is kept continuously operative at 250 deg. F. Coal is fed once in 10-15
minutes using a shovel and the slag is removed periodically.
Work disribution:
Workers are not strictly alloted or confined to specific
sections in the factory; they work in different sections and may be shifted from one
section to another according to work load and experience. In the present industrial
hygiene survey, 4 factories were included
for monitoring.
The parameters
monitored
in different sections re dust monitoring(particulate size), thermal
measurements and noise levels.
Results:
Table-4 Dust particulate concentration in different sections of the tea industries
Department
Pariticulate Concentration
________ (mppcf)_______
Sifting
1.
29.62 (3.70-5.50)
2.
Firing
4.93 (1.70 - 9.00)
Rolling
3.
3.05 (1.30 - 5.50)
4.
Whithering
2.34 (1.10-3.80)
5.
Packing
1.88 (1.80 - 2.60)
7
Industrial Hygiene Survey In Coir, Agarbathi And Tea Industry
Dust levels were high in sifting rooms (59.5 mppcf). The levels in other
sections ranged between 1.88 to 4.93 mppcf (Table - 4). A notable feature in the
dust is that generally it is respirable in character. At these dusts contain alkaloids
of tea, the effect of inhaling such dust should form an interesting study.
Envvironmental physical parameters ((Range of values):
A.
Temperature : The overall range of radiant temperature (GT) recording
are 19.5 deg C - 46 deg. C . The firing /drying sections are the hottest
because of the presence of the furnace. The highest radiant temperature
here recorded was 46 deg. C.
1.
2.
3.
4.
5.
Department
Sifting_____
Firing/Drying
Rolling_____
Whithering
Packing
GT(°C)
19.50- 35.00
28.00-46.00
WBGT(°C)
17.10- 26.60
20.43 - 30.90
17.20-21.80
16.30-23.50
22.10- 24.50
18.50-26.50
20.00-28.00
27.00-31.00
B.
Heat stress: WBGT index ranged from 16.3 to 30.9 deg . Except the
firing /drying section these were well within normal limits in all the other
sections.
C.
Humidity: Ranged from 23% - 96%; but the overall valued was within the
normal limits. Higher readings were obtained in the withering (44%-88%) and
rolling sections (33% - 96%).
Table - 5: Noise levels at different work spots
Department
Sifting
1.
Firing
2.
Rolling
3.
4.
Whithering
Packing
5.
D.
Noise dB(A)
78-102
70-84
78-86
76-92
98-102
Noise levels: The noise levels at the points measured (a total of 36 points
covering all sections) were higher than 70 dB. 31 points had a level between
70-90 dB and 5 points had levels above 90 dB. These were the fan end of
the withering section, sifting and milling machines, packing section).
8
Industrial Hygiene Survey In Coir, Agarbathi And Tea Industry
Further Suggested Reading:
1.
Annual Reports: National Institute of Occupational Health, (ICMR), Meghani
Nagar, Ahmedabad, 1979,145-152.
2.
Annual Reports: National Institute of Occupational Health, (ICMR), Meghani
Nagar, Ahmedabad, 1980,139-162.
3.
Rathnakara, U.P, Krishnha Murthy, V, Rajmohan, HR, Lalitha Nagarajan and
Vasundhra MK.
An enquiry into work environmental status and health of workers involved in
production of incense sticks in Ciry of Bangalore, Indian Journal OF Public
Health, Vol. Xxxvi, No.2, Apri- June, 1992, p.38-44.
4.
Report: Health Status of Tea Plantation Workers With Special Reference To
Their Occupation, Part I - Joint Study by Ross Institute of Occupational
Health (St. John’s Medical College), Bangalore and Regional Occupational
Health Centre (S), Bangalroe, 1979-1982.
ROHC-WHO Trg. Prog. On Occ. Health in Agricultural Sector, Feb. 8-12,1999: LN.-21
Health Hazards Of Workers Engaged In Coir, Agarbathi
& Tea Plantations
Dr. H. R. RAJMOHAN
Asst. Director, Regional Occupational Health Centre (South), Library and
Bangalore Information Centre Block, Bangalore Medical College Campus,
560 002.
This paper highlights the observation made by the scientists of Regional
Occupational Health Centre (South) with respect to the health hazards of
workers engaged in coir, agarabathi and tea plantations. Every occupational
health problem needs to be understood both from the point of occupational
environment (work environment) and also the dwelling environment where the
person spends most of the time. In this paper, the relevance of observations
made by the Centre through their multidisciplinary groups on the basis of
epidemiological guidelines are being discussed individually.
Health Hazards Of Workers Engaged In Coir Operations
Coir Industries
Coir is coconut husk, discarded after consuming tender coconut
water and the copra. This coir is of very great national economic importance for
India in general and Kerala in particular. The importance of coir industry is
also felt in other states. The coir industry used to dominate only in coastal
states because of coconut cultivation, climatic factors and other facilities for its
processing with
available natural resources. Nearly 60% of the world's
production is met by the Indian Coir industry.
Wherever the coir industry has existed, it provides means of sustenance
and lively hood. Because of the economic importance and enterprising
nature of the industry, industries developmental activities are being looked
after, encouraged financed and regulated through the Coir Board a
autonomous board under Union Government of India, Few states have also
their State Coir Board for the same purpose.
Coir Workers
Traditionally the coir workers are from the lower socio-economic
groups of population belonging to the areas where the industry is dominated. It
is a age-old occupation. It has seen the lime light in the last 2-3 decades. The
work force includes both male and female workers of the family. Hence, it
2
Health Hazards Of Workers Engaged In Coir, Agarbathi & Tea Plantations
can be said that coir industry is more a cottage industry participated by the
rural family units. Though there are specified jobs, same individual carrying
out multiple operations still exists because of their convenience, operational
reasons, individual skills and economic reasons.
From the point of work
force participation, coir industry is dominated by family participation.
It can be observed that the persons who are
partially disabled
because of elephantiasis are also employed in the industry. It infers that
the disabilities are not the hindrances and when there is no other job opportunity
elsewhere the person can think of earning lively hood through a job in coir
occupation. This peculiar and interesting circumstances are highly complex and
difficult to understand, to identify the specific occupational health problems
associated with coir operations.
Climate
As discussed earlier the workers are exposed to the prevailing general
environment, particularly in the coastal areas, it is warm, humid and sultry
environment. Most of the seasons with moderately heavy rain seasons. The
factory environment to some extent exposes the workers to the dusty and warm
environment
in few jobs. The influences of work environment and dwelling
environment are very much there on these workers.
Coir Work
Coir work is mainly carried out in two places, one is at the place of
dwelling and second at the factory. The main occupation generally practiced
are tree
climbing, dehusking, retting, beating,
hand spinning, wheel
spinning, weaving, dyeing, finishing, stencilling and other category of unspecified
jobs.
In the coir factory, the occupations include curling, dry beating, wet
beating, drying, spinning, bundle rolling, packing, bailing and becking of
bristles.
Morbidity Conditions
Some of the commonly noticed morbidity conditions in coir industry are
fever with cough, gastrointestinal disturbances, non-itching patch and other
skin diseases, asthmatic and chronic bronchitis and elephantiasis.
3
Health Hazards Of Workers Engaged In Coir, Agarbathi & Tea Plantations
The prevalence of chronic bronchitis was observed more among male
workers compared to control workers. Trends of higher morbidity rates among
retting, finishing and weaving male workers.
Bulk of the morbidity among female workers was observed in spinning
occupation. The observations were pointing in favour of synergic interaction
between smoking, geographical, climatic and ethnic factors.
No particular coir work had a higher risk of diseases
particular coir operation was absolutely free from disease.
nor
any
The Centre also attempted to introduce a ergonomic device called
hand grip made out of wood for the coir yam spinners who fed the raw husk with
their hands to the moving charakas. These workers were prone to develop
deep cut injuries of both the palms. The raw fibre was creating not only
injury and suffering, but also disability, loss of wages, financial problems,
absenteeism and loss of Productivity at large.
The observation of the trials conducted with this ergonomic handgrip
were :
1.
2.
The device reduces injuries of palms and there by alleviate the agonising
pain and suffering.
It was felt that the device need reduction in size, weight and
modifications.
HEALTH HAZARDS OF WORKERS ENGAGED IN AGARABATHI
MANUFACTURING
Agarabathi/lncense sticks are manufactured normally in cottage industries.
Karnataka has a large number of industries, ranging from small to large
employing 10 to 100 workers. Industry is less organised involving workers
of all age groups working at their place of residence. Incense and fumigants are
traditionally practiced methods of perfumes release by way of burning incense
sticks. The perfumes used are organic compounds which produce pleasant
olfactory sensation. The organic chemicals are predominantly esters, aldehydes
and ketones. Synthetic and natural oils like cedar wood oil, clove oil, amir, blins,
rose oil etc. are also used. Besides these many mixtures of chemicals of
unknown formulation are also used in the industry. The raw materials are jigatuthe bark of Machilus Makarantha as a binding agent, spent sandal wood
(sap wood), charcoal powder as a glowing agent, (occasionally the saw dust),
bamboo sticks, colouring agents and packing materials are used.
4
Health Hazards Of Workers Engaged In Coir, Agarbathi & Tea Plantations
Work Force
Mainly belongs to low socio-economic strata of society. They undertake
the job on piece basis and in bulk. The majority of workers earned a meager
income.
70.20% of workers are reported to be earning Rs. 1200/- per month.
High prevalence of illiteracy among workers existed.
and 51.54% of females were illiterate.
89.20% of males
Occupation
Mainly
a.
b.
c.
d.
e.
Mixing of raw materials and agarabathis
Dipping into and sprinkling of perfumes
Sorting and packing
Managerial & administration
Miscellaneous
(loaders, crate packers, sweepers,
drivers)
Rolling, Dipping and sprinkling
Sorting and packing is done by males.
exclusively
32%.
10%
43%
6%
9%
carried out by females.
Occupational Hazards
The subjective complaints narrated by the workers were :
22.16%
1. Low back ache
22.10%
2. Tiredness/sleeplessness
20.35%
3. Headache
19.91%
4. Irritation of eyes
15.32%
5. Joint pains
11.59%
6. Chest pain
7.22%
7. Running nose
7.00%
8. Abdominal pain
3.72%
9. Tremors
The complaints of female workers were more when compared to male
workers.
Low backache among the agarabathi rolling workers (females) was
the commonest complaint possibly attributable for their squatting posture
during the course of work.
5
Health Hazards Of Workers Engaged In Coir, Agarbathi & Tea Plantations
Sex wise distribution of illness observed by clinical examination were dyspepsia 4.37%, acne vulgaris 3.5%, hypertension 3.25%, acute tonsillitis
3.06%, DNS 3.06%, cataract 2.84%.
Among male workers acne vulgaris 7.73% and acute tonsillitis 5.67%,
DNS 3.09% were the commonest clinical findings.
Among female workers, dyspepsia 6.08% was the commonest followed
by cataract 4.56%, hypertension 3.80% and dermatitis 3.8%.
The complaint of low back ache more in dipping and rolling workers was
significant.
The symptoms like head ache, tiredness, joint pains and running nose
were equally distributed in all the sections.
The higher prevalence of eosinophilia among workers in all sections
was a salient feature (42.53%). This needs to be interpreted only after de
worming for any prevalent worm infestations, for identifying the possibility of
occupational allergens if any.
HEALTH HAZARDS OF WORKERS ENGAGED IN TEA PLANTATION
Introduction
This is one of the most important plantation crops in India and has a
national economic importance. Nearly 3,63,303 hectares of land is cultivated
for tea. 33% of global production is contributed by India. In India the plantation
are situated in Eastern India, Assam, Western ghats of South India (Nilgiris
and Annamalai Hills of Tamil Nadu, Kannandevan Hills of Kerala).
Tea is grown at high altitudes (elevation of 1000-3000 mt). The plants
are 4' tall, 6‘ across and grows like a bush. Tenderieaves make good tea.
Normally the tea leaves are plucked in Apr-June. Processing is done in
factory. The cultivation is like any other agriculture activity with special features.
Tea Plantation Workers
Workers are mainly from low socio-economic group of society, tribal
and hill region population, some are migratory work force from neighbouring
states. Both male and female workers are actively involved in plantation
activity.
Here
also
the
labourers involvement is more like a family
involvement rather than individuals. Approximately 8 lakh workers are
6
Health Hazards Of Workers Engaged In Coir, Agarbathi & Tea Plantations
employed in tea plantation alone. Nearly 56% of them are women work force.
The tea plantation comes under the Tea Plantation Labour Act 1954.
Occupations
Field Workers,
The occupations are mainly of 4 categories viz.,
Factory workers,
supportive workers and administration work force which
includes supervisory and managerial staff.
The details of specific occupations is given below :
Occupations In Tea Plantation
Field
Worker
Factory
Worker
Supportive
Services
Plucking
Cleaning
Planting
Manuring
Weeding
Pruning
Lopping
Spraying
Withering
Rolling
Fermentation
Drying/
Firing
Sifting/
stalk
extraction
packing
Furnace
operation
Sweepers
Gardeners
Helpers
Watchman
Driver
Store keeper
Electrician
Mechanic
Plumber
Medical staff
Welfare staff
Misc.
Manual &
Driving
AdminJ
Supervisory/
Managerial
Office Staff
Managers
Supervisors
Conductors
Plucking in the field and sifting/ stalk extraction in factory are mainly done by
women work force. Pesticide spraying is done by male workforce.
Occupational Health Problems/Hazards
The
occupational health hazards
commonly noticed among tea
plantation workers are mainly from physical, chemical, biological, mechanical
and psycho- social environment prevailing in plantation work place and place
of dwelling. The place of dwelling normally is the plantation itself.
The
employees encounter almost all the public health problems which are common
elsewhere. The details of causative factor is given below. Long hours of hand
work in incliment weather further adds to the adverse influences on health.
7
Health Hazards Of Workers Engaged In Coir, Agarbathi & Tea Plantations
General Environment
Geographic location/ :
Altitude
1000-2000 mt. Above sea level
Temperature
Ranges from 54-95% (54-summer);(95-winter)
Humidity
June-September also during winter season
Rainfall
100-110 mm.
Air Velocity
Cool breeze most of the year with stronger winds
Water Supply
Mountain springs, tube and open wells
Housing
Labour colonies, Pacca housing Damp proof floor &
tile concrete or asbestos roof
Sanitation
Septic tank
Chemical Environment
Fertilisers
Pesticides
ORGANIC
- Insecticides
- Miticides
- Rodenticides
- Fungicides
- Bactericides
- Nematocides
- Manure from
farm animals
- Bone meal,
- Composts
MINERAL
- Nitrogen
- Phosphorus
- Potassium
Biological Environment
- Very complex, include Flora and Fauna
- Wild animals/Game - accidental invasion, Mauling
- Domestic animals / live stock- injuries, zooming
Herbicides/
Weedicides
- Chemicals
used for weed
control
8
Health Hazards Of Workers Engaged In Coir, Agarbathi & Tea Plantations
- Snakes
- Insects and Pests (9)
- Diseases of tea bush (primary fungal -16)
- Helminths
- Insect vectors disease (Malaria and Gastro-enteritis)
Mechanical Environment
- Mechanisation
- Agriculture/Plantation implements
- Gradients
Psycho-Social Environment
- Life style
- Relationships
- Attitude
- Education
- Isolation
- Status of women
- Dependence
- Social stratification (labour/staff/management)
- Diversity
Occupational Health Hazards
These are similar to occupational health hazards common to other
agriculture labour. In addition to these, the specific influencing factors which
have a direct bearing on the health of tea plantation work force are
incliment weather, poor environmental sanitation, chronic effects of handling
agricultural chemicals, hazards due to close proximity to animals, increasing
mechanisation and stress related problems.
The Most Common Health Hazards (Symptoms & Signs) Are :
-
Leech bites, snake and scorpion bites
Insect stings
Worm infestations
Accidents (Men)
Backaches
Joint pain
Anaemia
Menstrual disturbances
9
Health Hazards Of Workers Engaged In Coir, Agarbathi & Tea Plantations
- Leukorrhoea
- Head aches
- Anonexia
- History of parasthesia & neuritis
- Varicose veins
- Insomnia
- Signs of Vitamin B deficiency
- Infective lesions of skin
- Respiratory infections
- Burning micturition
Coir dust being vegetable dust was thought to be a respiratory allergen, but
does not seem to have any effect on pulmonary function tests.
UNEP.
FAO
WHO
JOINT WHO/FAO/UNEP PANEL OF EXPERTS
ON ENVIRONMENTAL MANAGEMENT FOR VECTOR CONTROL
PEEM/7/87.7
ENGLISH ONLY
SEVENTH ANNUAL MEETING
.ome, 7-11 September 1987
EPIDEMIOLOGICAL PATTERNS ASSOCIATED WITH
AGRICULTURAL ACTIVITIES’ IN THE TROPICS
D.J. Bradley and R. Narayan
r
The issue of this document does not constitute formal
nuhliratinn
It should not be reviewed, abstracted
Ce document ne constitue pas une publication. II nt
doit faire I'objet d'aucun compte rendu ou resume n
«
EPIDEMIOLOGICAL PATTERNS ASSOCIATED WITH AGRICULTURAL ACTIVITIES IN
IN THE TROPICS WITH SPECIAL REFERENCE TO VECTOR-BORNE DISEASES.
David Bradley^ and Ravi Narayan^
Introduction
For most rural populations of the tropics, agriculture is the
normative occupation.
Therefore our picture of the health and diseases of
tropical communities consists of the epidemiological patterns associated
with agricultural activities. The patterns are complex and diverse.
Tropical peasant agriculture is usually characterized by a high infant and
child death rate, malnutrition which may be seasonal, acute respiratory
infections and diarrhoea as the main causes of death, particularly of
children, frequent tuberculosis and skin infections, trauma and disability,
and infection by a variety of endemic parasitic worms and protozoa at high
prevalence but showing much regional variation. They will include many
vector-borne diseases among which malaria, filariasis, arbovirus
infections, schistosomiasis and the other human trematode infections, and
the haemoflagellate infections are of particular importance (Table 2).
Typically, the subsistence farmer will live with his family on or near to
his fields and there will be no sharp boundary between his occupational and
general health.
To separate the two is neither feasible nor particularly useful. The
person’s health problems are experienced as a whole and they are the concern
of the Ministy of Health.
Some diseases may be linked to specific
components of life and of activity and may be open to change, but in general
there will be a health care system concerned with all the local diseases and
health problems and the agriculture-related diseases can only be approached
by observing health changes if the people migrate to a city and nothing else
changes in the environment.
Even then, the multiplicity of changes is so
great that to relate all the differences to loss of agricultural activity
will be clearly mistaken.
While it is difficult in the subsistence situation to separate
agricultural occupational health problems from the remainder of the
community’s health, once changes in agricultural activity take place the
consequent health changes may be more readily identified and measured, We
now therefore concentrate on the health consequences of changing
agricultural activity, Health problems may get worse or better - too often
different factions of those who study the problem only focus on one of these
aspects. We first analyse the types of agricultural change and their health
effects, then illustrate the effects of common groupings of changes, and
thirdly review a set of particularly important types of agricultural change
and their epidemiological implications.
We present a broad rather than a detailed picture, both because of
space limitations and also because many of the papers that follow will
describe particular aspects of the problem or specific examples.
Agricultural change tends primarily to involve alterations in the basic
environment, domestic plants and animals, and farming methods (Table 1).
The two main types of environmental modification are the provision of
increased, or more controlled, water for vegetation growth and the opening
up of additional land.
I
1 Director, Ross Institute for Tropical Hygiene, London, UK
^Academic visitor, London School of Hygiene and Tropical Medicine,
London, UK
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Water resource developments
Water resource developments have been much studied and may comprise
impoundments of water in artificial lakes, sometimes of huge size, and
irrigation systems to bring the water to the fields and plants. The
resulting increase in availability and diversity of surface water both in
area and in duration through the year tends to lead to increased populations
of still-water vectors, particularly mosquitoes and water snails, The
torrent-breeding Simulium vectors of onchoceriasis may have their habitats
destroyed by inundation. The converse aspect of water management, drainage
of swamps and waterlogged areas, will reduce breeding of mosquitoes and the
amphibious snail hosts of Schistosoma japonicum. While increased surface
waters with more vector habitats and increased vector populations will tend
usually to more mosquitoes biting man, contact between snail parasites and
man will be dependent on the detailed changes in water availability man/vector contact may even be reduced due to a dilution effect.
Land Use Extension
Extension of land use brings different vector hazards, chiefly
resulting from man’s intrusion into new ecosystems with disturbance of
parasite life cycles maintained as zoonoses in the undisturbed environment.
Leishmaniasis provides a clear example, both in the deforestation on the
Amazon region where agricultural settlers are exposed to Leishmania
braziliensis causing muco-cutaneous disease and in the southern USSR where
cutaneous leishmaniasis, transmitted by sandflies between huge populations
of the colonial burrowing gerbil Rhombomys opimus is a major hazard to
farming settlement (Lainson et al., 1963). More lethal problems from
sleeping sickness have resulted from agricultural resettlement or patchily
cleared secondary forest in South Busoga, Uganda. Audy has emphasized the
importance of eco-tones in the epidemiology of vector-borne zoonoses and
land use extension creates extended ecotones, edge-effects between different
ecosystems (Audy, 1968).
Malaria outbreaks in Thailand due to Anopheles
dirus (formerly called A. balabacensis), and to be described by Sornmani,
are of this type also.
An ecologically comparable situation is where man enters a habitat for
some form of agricultural activity of a more hunter-gathering type and
thereby enters a zoonotic life cycle habitat. The chewing-gum collectors of
Honduras are exposed to Leishmania mexicana, which mutilates their external
ears, in this way (Garnham, 1971). Another example is Kyasanur Forest
Disease, an arboviral infection in Karnataka State, South India where
affected men and cattle have previously come in contact with Haemaphysalis
spinigera, a monkey biting hard tick during excursions into the forest
(Singh, 1971).
Domestic animals and cultivated plants
Changes in plants and animals for domestic use may affect vector-borne
Many of
diseases, usually because they require changed cultural practices,
the high-yielding varieties of rice and wheat, which are the key feature of
the ’’green revolution" have requirements for water and fertilizer that
prolong the period of available surface water for vector breeding.
The time scale of health impacts on agricultural change are both
variable and complex. A common effect of water resource developments is to
decrease seasonal effects, to make irrigation water available in the dry
season.
So vector presence changes from seasonal to perennial. Often the
loss of seasonality will be accompanied by increased vector populations, but
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least as harmful as the perennial transmission of the forest zone in West
Africa.
The degree of persisting seasonality will depend on small scale
decisions.
For example, with the multiple cropping of irrigated rice the
fields may be planted synchronously, or they may be totally staggered with
the consequence that there will always be rice present at the particular
growing stage that provides the best habitat for a particular vector.
The loss of seasonality may also remove the "hungry period" and its
accompanying seasonal overwork and synchronous malaria transmission that lethal combination which so raises the seasonal death rate in the
savannah of West Africa and elsewhere.
Some changes will be of a secular type on a very long timetable. Thus
the eutrophication sequence of lake Volta in Ghana is now settling after
some 15 years, during which there were massive increases and now falls in
the submerged macrophytes which acted as habitats for the snail intermediate
hosts of urinary schistosomiasis (Bulinus truncatus rolfsi) (Obeng, 1975).
f
The trend towards multiple cropping which depends on both irrigation
and appropriate crop varieties can, in the case of rice, increase the period
when the ricefields provide breeding habitats threefold in the absence of
However, selection of crop
measures to restrict mosquito larval survival,
rotations within the year can reduce the time when free surface water is
present.
Changes in livestock may affect vector-borne disease patterns in
complex manner.
Increased animal populations may direct mosquito biting
activity away from man, especially if the livestock pens are sited between
the breeding sites and human settlements. On the other hand, the stock may
act as amplifier populations, allowing the great proliferation of
arboviruses normally transmitted at a lower level among wild birds or
mammals.
Subsequently the infection may spill over into the human
population, as may occur with Japanese encephalitis virus, amplified in
domestic pig populations.
Livestock populations, by increasing food
supplies for mosquitoes and tsetse, may also encourage larger vector
population than otherwise would be the case, but little quantitative data
are available.
In the case of schistosomiasis in East Asia, domestic
animals are susceptible and may play a role in maintaining the parasite life
cycle in the Philippines and elsewhere.
Farming methods
Changes in agricultural methodology, such as increased mechanization
and the use of pesticides, herbicides and fertilizers, will often affect
vector-borne disease transmission but it is difficult to generalize about
the precise consequences. For example, insecticides applied for
agricultural purposes may initially also reduce vector insect populations
substantially, they may select insecticide-resistant strains, and they may
continue to reduce natural populations of other invertebrates that limit the
vector breeding success.
The outcome after a time may be more rather than
less disease transmission, but the time scale of such changes may vary
greatly.
Herbicides may render the irrigation channel less suitable for
vector breeding (or more so for other species), they may be lethal to snail
hosts of trematodes, and the medium-term ecosystem changes may influence the
vector populations in complex ways.
Eutrophication from fertilizers may
indirectly increase snail breeding and have complex effects on the balance
of aquatic organisms.
Increased mechanization, to be discussed fully by Service, has both
direct effects through changes in the ricefield or other agricultural
environment that mav decrease snail populations by better clearing of
FEtn//rwr/o/.I
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vegetation from canals, for example, and indirectly may lead to larger
fields, better levelling, drainage of marshy areas, and a sharper separation
of land and water which will generally tend to decrease vectors of
disease.
Most forms of mechanical equipment will also tend to reduce persona),
contact of farm workers and the aquatic environment.
Thus,
schistosomiasis transmission will be reduced, so will leptospirosis with its
rodent reservoirs, but no invertebrate vector. Where mechanical means are
used to harvest crops or cut sugar-cane there will be a decreased risk of
snake-bite (a substantial hazard in some parts of Asia).
Increased
sophistication of methods short of mechanisation may also reduce
schistosomiasis in those working in water while better clothing will
decrease leech bites and insect bites among plantation workers such as teapluckers•
As agricultural activity and culture methods become more
sophisticated and higher yields are systematically sought, a more evenly
cultivated landscape will result.
The ecotones, patches of waste land and
water will be reduced and many disease vectors will decrease.
There may
however be larger populations of a few vectors whose ecological preferences
happen to coincide with the spreading pattern of agriculture.
c
Changes in people, agents of disease and vectors
Types of agricultural change are outlined above.
Either in order to
achieve them or following their introduction, substantial human population
changes frequently occur.
The most obvious are immigration of farmers to
newly opened up or newly irrigated lands.
Often they may come from overpopulated hill areas where endemic malaria and other primarily warm climate
diseases are uncommon.
Such immigrants suffer heavily - ’’malaria of the
tropical migration of labour" is, for example, a well-known and named
entity.
The malnutrition which often occurs in the first years in a new
site takes its toll and may exacerbate other diseases.
The immigrants may
precede the provision of health services.
Unplanned immigrants,
especially fishermen invading water resource developments, may suffer
from vector-borne diseases such as schistosomiasis but benefit in
economic terms (Pesigan, 1958).
Even more unfortunate are indigenous
inhabitants displaced by the agricultural innovations of the water resource
developments undertaken to provide them. Their health problems are
compounded by poverty and upheaval. Resettlement is usually inadequate
and a health service to take particular care oo new disease hazards is
unavailable .
Where the agricultural shift is to cash crops from subsistence, family
nutrition usually suffers, at least in the short run, from the loss of local
cereals and pulses, sometimes from increased labour demand and less time for
child-rearing.
The effect of malnutrition on vector-borne diseases is
complex and agent-specific, they are not always made worse.
Patterns of settlement often change from scattered homesteads to
compact villages.
Health care can be made more accessible but some forms
of disease transmission - hookworm and other geohelminths, the childhood
virus fevers, and other infectious conditions may become more frequent.
Common source disease outbreaks will be larger.
Many activities, and their health consequences, will tend to become
less seasonal than before, and the ’’hungry season’’ that coincided often with
maximal transmission of vector-borne disease, may become less pronounced.
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New pathogenic organisms may infect man: new in the sense that they
were previously unknown in the locality. This may be because of the
environmental changes in agricultural practice described above, introduction
by immigrant farm workers, or amplification of zoonotic viruses by
introduced livestock.
Infections already present may become more
prevalent, and in the case of helminthic infections the parasite burden may
be increased, with a resulting risk in overt disease.
Thus the Egyptian
transition from annual flood irrigation to perennial irrigation in the Nile
valley haa led to a changed balance between schistosome species and a
greater intensity of infection.
Vector populations may increase in numbers, or in a few cases decrease,
have an extended season of activity and undergo the many complex changes to’
be described in subsequent papers at this conference.
The emphasis in the above summary has been oo the health effects of
agriculture as rmediated by change in the natural and biological environment,
But agricultural change has social and economic effects and their effect on
human health may be yet more important,
Effective agricultural development
will raise aggregate income, with potential health benefits, but it often
also increases disparities of income and the poor, usually landless
labourers, may become yet poorer and marginal farmers become worse off
with consequences for nutritional status and access to health services’
Consequential inevitable urbanization of the poorest farmers, with its
different health hazards, may be a consequence of agricultural change.
A further group of indirect health effects follow from the various
types of seasonal migration related to agriculture, from the regular
traditional transhumance of mountain pastoralists to the much larger scale
seasonal labour requirements for planting and harvest of sugarcane in
Thailand, cotton in the Sudan, and various crops in Asian Turkey. In the
last case, problems of welfare taxation greatly complicated control of
malaria; both there and in Thailand, as is often the case, migrant labour
chiefly suffers from the endemic malaria even though local perception may
be reversed, with the migrants being blamed for the malaria which they have
in fact contracted only on arrival.
Housing for such temporary migrants
is not only often very bad, but the transient structures may lack proper
walls ans be difficult to spray with residual insecticides against mosquito
vectors.
Permanent agricultural housing over large tracts of South America
is liable to colonization by reduviid bugs, who by their nocturnal blood
feeding on inhabitants may transmit Chagas’ disease.
Where livestock shares the farmers’ dwelling at night, other vectorborne disease problems are locally significant.
Cattle ticks of the genus
Ornithodorus in Tanzania will travel up the bedposts, especially if they are
fixed into the ground, and transmit relapsing fever among the inhabitants.
In areas of sheep herding domestic dogs become important in the transmission
of hydatid disease to man while rabies is a hazard also.
The patterns of disease observed in different agricultural communities
will depend upon the specific agricultural variables listed in Table 1
together with the local features of climate, degree of socio-economic
development, and cultural variables.
Certain broad patterns may emerge, in
different geographical regions, though the vector-borne diseases in
particular will tend to show micro-geographical variations in both the
types
and prevalences of diseases encountered.
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Implications of agricultural types
Asian rice cultivation will be dominated by malaria, schistosomiasis
and Japanese encephalitis, with smaller contributions from gastro-intestinal
and hepatic flukes.
But all these diseases are patchily distributed and in
many areas malaria is prevalent but unrelated to agricultural activity. ,
Similar problems occur with irrigated rice elsewhere, though different
arboviruses will replace the Japanese encephalitis, especially in the
Americas, and the filariases will play a variable role.
The problems of extending cultivable land into forested areas are
likely to include zoonoses such as leishmaniasis, sleeping sickness and some
arbovirus infections while some Asian malaria vectors flourish in such
ecotones as does scrub typhus.
Plantation agriculture has usually followed control of malaria, and
particular health hazards are related to labour-intensive activity in close
contact with trees and shrubs where insect stings, leeches and snakebite may
be frequent. A range of vector-borne diseases may occur but are more easily
controlled than in the unorganized rural agricultural sector of contiguous
areas.
The move to highly mechanized advanced agriculture is accompanied by
massive falls in the farming population, larger plots and more capitalintensive methods than usually tend to reduce the hazards of vector—borne
disease. Contact with vector snails will tend to fall, even if they are
present in the water bodies, and the main residual problems will be vector
mosquito breeding if rice or similar crops are grown and health hazards from
seasonal labour migrants where these are needed for harvesting.
Mechanization and/or sophistication of technology are invariably involved
with greater capital intensive production reducing labour demand and hence
increasing rural unemployment, especially if alternative employment through
rural or urban industrialization cannot keep pace.
This could further
complicate the situation of poverty and disease.
Particular issues of agricultural change.
Various Arcadian memories or dreams exist concerning healthy
agricultural practices and environments in the past, and hunter-gatherers
seem to often have lighter levels of parasitic infections that do those in
settled agriculture. The ancient hydraulic agricultural communities of Sri
Lanka were said to have a relatively low incidence of vector-borne disease
as a result of having a network of small units serving limited populations,
without use of pesticides and fertilizers but with careful maintenance of
tanks and canals and carefully followed cycles of seasonal flooding and
drying out of the channels.
Similarly, in more recent times the Sudan
Gezira Board achieved good control of schistosomiasis and of malaria by a
complex of environmental and behavioural measures enforced with an iron hand
It is far from clear how
in the earlier years of that irrigation scheme.
far, in the absence of coercion or very strong other incentives it is
possible to have an environmentally and behaviourally determined relatively
safe agricultural programme in the tropics involving water resource
development but certainly this area needs further study.
The practical issues of attempting a return to this Arcadia are raised
by considerations that have increased since the availability of greater
evaluated experience of "the green revolution" and the awareness of an
increasing range of detrimental effects that have accompanied the increased
food availability - not the least of which are the pesticide "treadmill
effect, oesticide hazards, and the socio-economic effects mentioned earlier.
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The quest for sustainable agriculture - that produces higher yields but
with very limited fertilizer and other modern sector inputs has been gaining
ground through experiments in Japan, India, USA and UK.
This situation may
be good for environmental control of vectors but little directly relevant
research^ is yet available and needs to be planned for.
Development strategies involving both agricultural and industrial
interventions are increasingly beginning to focus on those sections of
society who do not adequately participate or benefit from the existing modes
of development.
While environmental and socio-economic changes in the
community have been adequately documented, only in some limited specific
cases has data about the health and nutrition effects of agricultural
development been applied in impact evaluation. Much more needs to be done.
The analysis of health consequences of agricultural change has
predominantly considered one disease at a time and traced the biological and
behavioural determinants of transmission.
Less often, a single change in
agriculture or a single intervention has been considered in relation to all
its health consequences, as when the effects of increasing irrigated rice
fields or introducing piped water are considered.
But the farming family
see their health as a whole in relation to themselves rather than a single
agricultural change or occupational hazard. Moreover the farming community
is essentially a stratified community divided into different groups by
socio-economic status, land ownership and wage relations.
Agricultural
change whether single or multidimensional, affects different groups in
different ways - quantitatively and qualitatively.
There is a need for
community based epidemiological studies that will consider agriculture as
one of the many determining variables for health and measure its impact on
the stratified agricultural community.
This is not only to give a sense of
proportion but also to view the problems and thus seek solutions from the
viewpoint of the farmer and the agricultural community.
References
Audy, J.R., (1968). Red Mites and Typhus, Atholone Press, London.
Garnham, P.C.C.,(1971). Bull.Wld.Hlth.Qrg. 44: 521-527
Lainson, R., et al., (1963). Trans.Roy.Soc.Trop.Med.Hyg . 57: 242
Loevinsohn, M. E., (1987). Lancet, June 13, 1987. pl359.
Obeng, L.E., (1975). In: Man-made Lakes and Human Health, N.F. Stanley and
M.P. Alpers (Eds), Academic Press, London.
Pesigan,
, et al., (1958). Bull.Wld.Hlth.Qrg, 18: 481-578
Singh, K.R.P., (1971). Ind.J.Med.Res. 59: 312
.
TABLE 1: Epidemiologically Relevant Aspects of Agricultural Change
New or Qualitatively
Changed
Increased Quantitatively
PRIMARY AGRICULTURAL CHANGES
ENVIRONMENT
Water resources development
Land use extension
ORGANISMS
Plants
Livestock
CULTURAL METHODS
Chemicals
Machinery
JO
io
a
Reservoirs, dams. Land
drainage. Irrigation
schemes
Irrigation canals
Clearing, deforestation
Extensive ecotones
New High-yielding varieties
Move to cash crops
Intercropping
Multiple cropping
New breeds
Increased animal husbandry
Pesticides
Herbicides
Mechanization
Fertilizers
SECONDARY EPIDEMIOLOGICAL CHANGES
People
Settlement
Changes in Seasonal Patterns
Nutritional status
immigration
Vectors
Species changes
Population changes
Disease agents
Species changes
New introductions
New hosts acquired
/Amplification by
stock
Table 2.
page 9
Major vector-borne diseases that may be related to agriculture
Protozoa
Malaria
Anopheline mosquito vector may breed in
standing water
Sleeping sickness
Tsetse-borne disease related to extending
land use into forest
Chagas’ ^Disease
Transmitted by bugs living in walls of
houses, especially when livestock there
Visceral leishmaniasis
Sporadic, sometimes epidemic in semi-arid
regions, sandfly transmitted
Cutaneous leishmaniasis
Rodent reservoirs disturbed in Asian land use
Muco-cutaneous leishmaniasis
Forest zoonosis of Amazon forests, to man
during deforestation
Trematodes and Cestodes
Schistosomiases
Major irrigation problems spread by
aquatic and amphibious snails
Hydatid
Dog tapeworms, larva usually in sheep,
harmful to man in sheep-herding areas
Other tapeworms
Problems where undercooked beef and pore
concerned
Other trematodes
Transmitted by snails through undercooked
freshwater animals
Nematodes
Guinea-worm
Transmitted through defective water supplies
by water-flea type crustacean. Big effect on
agriculture
Filariases
Transmitted by anopheline and culicine
mosquitoes
Oncherciasis
Transmitted by fast-water breeding
Simulium flies
Other microbes
Relapsing fever
Tickborne problem where stock and man
share accommodation
Yellow fever
Hazard at forest edge (and in urban areas)
Dengue
Japanese encephalitis
Other encephalitides
Other arbovirus infections
Viruses transmitted by mosquitoes, mainly
culicines, breeding in irrigated fields and
standing water
Scrub typhus
Mite-borne zoonosis of the forest edge
Non-vector-borne diseases
Leptospirosis
Rabies
Snakebite, leeches
Especially problem of marshy and irrigated
agriculture
Hazard of pastoral areas where dogs used
Hazard in forest plantation agriculture
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