There are various aspects of pesticide hazards, but it is proposed to deal here with only one aspect, viz., the pesticide hazards to man under present-day conditions in India.
Basic Points to be Kept in View:
The following basic points have to be kept in view:
(a) Public concern about hazards of large-scale use of pesticides is universal. Advanced countries like USA and UK have taken cognizance of these hazards from the very beginning. In UK the Minister of Agriculture and Fisheries appointed a working party under the chairmanship of Professor Zuckerman in 1950, and since then several committees have gone into the matter. The final stage is represented by Cook’s reports (1964) in which specific recommendations have been made for continuing or discontinuing the use of particular insecticides for particular purposes.
In USA the actions taken have been all the more legalistic, and a number of Acts and Amendments have been passed from time to time since 1938. The latest position is represented by the report of the President’s Science Advisory Committee (1963). In 1963, WHO and FAO held a joint meeting on the evaluation of the toxicity of pesticide residues. Thus, it is imperative for India to take serious note of the problems of pesticides and to create effective organizations for keeping the hazards under check. In fact, this action is overdue.
(b) At the same time, because of the immense amount of good done by pesticides, particularly in increasing the efficiency of production and in preservation of food, the hazards involved must be properly weighed against this benefit before accepting or rejecting the use of pesticides. It is difficult to visualize a total stoppage of the use of pesticides in modern agriculture.
Before the discovery of DDT, agricultural scientists used to dream of a persistent contact poison because all the inorganic insecticides then used acted only as stomach poisons and hence were of limited utility. The present wide-spread concern about the adverse effects of modern pesticides is a testimony to their popularity.
(c) All modern advances involve a certain amount of risk, and all human activities are subject to accidents. Hence, accidents associated with the use of pesticides, such as those which occurred in Kerala some years ago and those subsequently reported from the Punjab, should lead only to greater awareness and alertness of the public and the governments; they should not be allowed to create undue scare in the public mind. Even in advanced countries like Japan there have been several accidental deaths every year from Parathion, the insecticide involved in the Kerala accident.
(d) Developing pesticides is a time-taking and costly process. Each marketable chemical meant an investment of 1 to 3 million dollars before it was made available. For investment of such magnitude the industry certainly requires proper incentives, which should not be marred by taking an unbalanced view of the situation.
(e) When knowledge is scanty, precautions are all the more necessary. It is often argued that restriction on the use of pesticides in the absence of definite information of the harm done by them is not quite scientific. It may be pointed out that collection of necessary information is bound to take considerable time, and it is not unlikely that if a harmful chemical is already in indiscriminate use it might well cause enough damage before sufficient scientific data regarding its hazards are collected.
Types of Pesticides Hazards:
There are various types of hazards of the large-scale use of pesticides in the fields of agriculture and public health.
The following classifications from different angles give an idea of their nature and magnitude, which have to be kept in view in recommending precautions against them:
(a) Hazards at Different Stages:
(i) Accidental and intentional poisoning. Because most pesticides are poisonous to warm-blooded animals including man, chances of accidental poisoning are always there. These poisons can also be used for suicide or homicide. These hazards, however, are not peculiar to pesticides; they are common to all kinds of poison, including sleeping pills.
(ii) Operational hazards during manufacture and distribution of pesticides.
(iii) Operational hazards during application of pesticides.
(iv) Post-application hazards due to pesticide residues.
(b) Risks to Different Categories:
Effort has to be made to safeguard the following categories from pesticide hazards:
(i) Pesticide users
(ii) Factory workers
(iii) Consumers of treated food and fodder
(iv) Third parties, such as children, animals, passers-by and so on.
(c) Graded Types of Pesticide Toxicity:
(i) Acute Toxicity:
Two types of acute toxicity have to be reckoned with, i.e. oral toxicity from accidental or intentional ingestion of the pesticide or heavily contaminated food, and dermal toxicity from spilling of the pesticide concentrate over the body or garments of workers. Although oral toxicity is more acute and dangerous than dermal toxicity, it is the latter which is more difficult to avoid.
(ii) Subacute Toxicity:
This occurs when exposure continues for several days so successively and excessively that the enzymatic function does not fully recover and the poisons are not completely eliminated during the night’s rest. Such a situation may arise in the case of farmers who try to complete their spraying schedule within a short period.
(iii) Subchronic Toxicity:
Workers in pesticide factory, personnel engaged in pest control and vector control, and aircraft pilots may become repeatedly exposed to small doses for a full season of pest control.
(iv) Chronic Toxicity:
This is largely from pesticide residues in food and environment. Every nation and its laws are generally prepared adequately to face the problems of acute toxicity, but those of subacute and chronic toxicity are more difficult to deal with. The public, in general, has become most concerned about hazards of chronic toxicity due to increasing quantities of pesticides being used in modern agriculture.
(d) Inherent Types of Operational Hazards:
These are mainly due to:
(i) Spilling over of pesticide formulations in careless handling,
(ii) Inhaling of the pesticide mist or dust, and
(iii) Coming in contact with treated crops or surfaces, or handling of used equipment.
Generally, protective clothing and gasmasks are recommended for avoiding operational hazards, but these recommendations are generally impracticable in the excessive heat and humidity of tropical and subtropical countries.
(e) Indirect Hazards through Food Chain:
Public safety has to be ensured not only against direct poisoning by pesticides but also against indirect poisoning through the food chain. Contamination of fodder or dairy premises may lead to excretion of the pesticide in milk. Grazing by cows and goats on treated pastures may lead to contaminated milk and meat. At times this food chain leads to a progressive concentration of the pesticide.
Review of Recommendations of Various Committees in UK and USA and of FAO and WHO in the Light of Conditions in India:
It was easy for the President’s Science Advisory Committee (USA) and the Cook’s Committee (UK) to examine each of the uses of particular insecticides because in either country there exists adequate official machinery for formulating and implementing what may be called official recommendations for pest control. In the USA there is a Federal Pest Control Review Board and an Interdepartmental Committee on Pest Control.
In the UK this work is carried out by- (i) the Agricultural Chemical Approval Organization and (ii) the Advisory Committee on Poisonous Substances used in Agriculture; Food and Storage and its Subcommittee; and Veterinary Products Safety Precautions Scheme. In India there are no organizations like these. Although there are a number of booklets containing recommendations for pest control, yet all these recommendations are from individuals and on individual’s personal responsibility.
There is no organization or body to scrutinize all these varied recommendations and to formulate such agreed recommendations as may guide, and be obligatory for, those engaged in control operations. Thus, recommendations for the control of different pests vary widely as regards the active chemical to be used, its formulations, and the quantity to be applied per unit area. For checking hazards it is necessary that these recommendations are first reduced to a small manageable number and then scrutinized from the point of view of residue and health hazards.
We should also constitute what may be called the Insect Pest and Disease Control Advisory Committee (IPDCAC), which should make official recommendations for the control of different pests and diseases and also for integrated control schedules for different crops. Its functions should be somewhat on the lines of the Variety Release Committee, which considers the varieties recommended by plant breeders and officially releases some of them for adoption.
In the same manner, the IPDCAC should examine all methods of pest control and officially approve them before the extension workers carry them to the cultivator. These recommendations should be reviewed at periodical intervals in the light of further knowledge regarding their efficacy and the hazards involved in their implementation.
In both UK and USA there is arrangement for registration of pesticides. No such arrangement exists in India. In the USA and UK the manufacturers have to supply detailed toxicological data before they are allowed to market the pesticides. These data, with necessary modifications, can be adopted for Indian conditions; but pesticide formulators and distributors should be required also to supply accumulated data on pesticide residues on various crops for which their use is recommended.
Public concern in UK and USA regarding pesticide hazards has been realistic, based on the results of monitoring of pesticide residues. In India, in the absence of such information, it is not possible to make specific recommendations. It is, therefore, suggested that provision should be made for monitoring pesticide residues mainly to assess the extent of hazards involved in the use of pesticides in agriculture, forestry, fisheries, and veterinary and public health including hazards resulting from mothproofing of human clothing.
Work done at the IARI has shown that this monitoring work will require careful standardization of each technique to be used in the chemical analysis of a particular pesticide used on a particular commodity. Investigations on residues of pesticides have been going on for some years at the IARI.
Studies on the persistence of some commonly employed pesticides, such as DDT, BHC, Lindane, Aldrin, Endrin and Malathion, with respect to different crops and crop materials have provided basic information for toxicity studies related to man and animals, modification of application schedules, safe interval between application and harvest, and so on.
This is, however, only a small beginning, and much more remains to be done with respect to many more chemicals, crops, soils, and climatic conditions in various regions of the country.
That the recommendations made in other countries have to be carefully scrutinized in the light of conditions in India is borne out by the fact that the main risk from pesticide residues, on the basis of which Cook’s recommendations are made, appears to be for predatory birds. Indian agriculture is becoming more and more concerned about the number of species of birds that have become serious pests of both agricultural and horticultural crops.
The balance sheet of the utility and harmfulness of different species of birds taking mixed vegetable and animal diet is yet to be worked out. It has also to be decided how far predatory birds are useful in controlling the pests against which the pesticides are used.
The recommendations of the American committee are:
(i) To assess the level of pesticides in man and his environment,
(ii) To formulate measures which will augment the safety of the current practices,
(iii) To undertake needed research for development of safer and more specific methods of pest control,
(iv) To suggest amendments of public laws governing the use of pesticides, and
(v) To educate the public. For the first purpose the committee recommended the development of a programme for collecting comprehensive data so that levels of pesticides can be determined in occupational workers and others, and a continuing network to monitor residue levels in air, water, soil, man, wildlife and fish.
For the second purpose its recommendations are to improve and augment the organization for reviewing:
(a) Residue tolerances and the experimental studies on which they are based, and
(b) Current and proposed control and eradication programmes to reduce their hazards.
For the third purpose it recommended that emphasis on research should be shifted from broad- spectrum chemicals to such items as could lead to selectively toxic chemicals, non-persistent chemicals, selective methods of application, and non-chemical methods as well as more research on toxicity studies related to man.
For the fourth purpose it recommended that public laws should be reviewed to make them more effective; for example, it should be required that every pesticide formulation carries its official registration number on the label. For the fifth purpose it recommended that programmes of public education on the toxic nature of pesticides and their proper use should be augmented.
In the joint meeting of FAO and WHO (1963) on the evaluation of toxicity of pesticide residues in food a very useful concept of ‘acceptable daily intake’ of different pesticides, was developed. On the basis of all toxicological data available, an effort was made to determine the quantity of each insecticide in terms of mg/kg body weight which man could daily consume without appreciable risk for his full life time. It was suggested that this information could serve as a basis on which different nations might form their own recommendations on the permissible limits of contamination by each pesticide on each commodity based on average consumption of each commodity and average weight of individuals.
Review of Precautions Generally Recommended, and Additional Suggestions:
(1) Measures to Prevent Hazards at the Stage of Manufacture and Formulation:
(a) Measures Generally Recommended:
There is an Industrial Hygiene Division of the US Public Health Sciences which issues instructions to the industry to adopt uniform and co-operative steps to prevent hazards.
The instructions include provision of:
(i) Proper exhaust ventilation,
(ii) Suitable working clothes, and
(iii) Adequate washing facilities.
The primary producers of the chemicals have also extended their responsibilities by advising and controlling the activities of the firms that formulate their products.
(b) Additional Measures Suggested:
The following further measures are essential:
(i) Authority with the government to inspect pesticide manufacturing plants.
(ii) Prevention of faulty disposal of factory affluents and wastes; pesticide firms, manufacturers and formulators to obtain a waste disposal permit.
(iii) Prevention of dangerously adulterated and mislabeled pesticides from reaching the market, and provisions for their seizures.
(iv) Provisions to see that the manufacturing enterprise is not located near populated areas.
(v) Regulations for disposal of empty pesticide containers.
(vi) Provision of warning facilities in cases of excessive contamination during manufacture and formulation of toxic materials.
(2) Measures to Prevent Hazards at the Stage of Marketing:
In the USA the Insecticides, Fungicides and Rodenticides Act provides that every product must have attached to it a label showing:
(i) Name and address of the manufacturer,
(ii) Name, brand or trade-mark under which the chemical is sold,
(iii) The net content,
(iv) Ingredient declaration,
(v) Appropriate warning or caution statement when necessary to prevent injury to man, livestock vegetation and useful invertebrate animals,
(vi) Labels of the world ‘Poison’ in red skull and cross bones, and a statement of antidotes. Provision is made also for testing products as they are encountered in the regular channels of trade to determine whether they are in compliance with the law. Those that are found to violate the law may be seized by the government and removed from the channel of trade.
Additional Suggestions:
(i) The internationally accepted common name must be indicated conspicuously on the labels.
(ii) The sale of pesticides should be restricted to farmers who are educated and trained for the purpose and who use them under the supervision of plant protection, block development, or other officials of the state department of agriculture.
(iii) Pesticidal formulations, particularly concentrates, should be marketed in suitable containers of handy size so that there is least chance of unconsumed material being left.
(3) Measures to Check Hazards to Workers Engaged in Pesticide use Programme:
In the UK the Agriculture (Poisonous Substance) Act is designed to protect agricultural workers by ensuring that they are supplied with protective clothing when working with the more toxic pesticides included in regulations made under the Act.
In India the following recommendations are generally made:
(i) Use of protective clothing,
(ii) Operators not to work for more than 8 hours a day,
(iii) Operators to be checked by a physician periodically.
Further Suggestions:
(i) Protective clothing should be specified, keeping in view the weather conditions under which the operators have to work. Operational studies on this aspect need to be carried out; for example, it will be necessary to give periodical recess for pesticide operators, and to allow each operator to stop work for a suitable period and take rest in fresh air before resuming it.
(ii) The operators should be trained in safe handling of insecticides.
(iii) Popular publications in local languages on correct methods of application, personal hygiene and protection as well as storage and disposal of containers would be useful.
(4) Measures to Check Post-Application Hazards:
A. Measures Adopted in Other Countries:
(i) Fixation of tolerance limits for each pesticide on each commodity- The Pesticide Chemicals Amendment to the Federal Food, Drug and Cosmetic Act (Public Law 518) (The Miller’s Bill) in the USA provides practical methods of establishing safe tolerance for residues of pesticide chemicals in food. Under this law the petitioner who requests establishment of a safe tolerance for insecticides submits data to the government to support the application.
Information is required on the following:
(a) Name, chemical identity and composition of the pesticide chemical
(b) Amount, frequency, and time of application of the pesticide chemical.
(c) Full reports of investigations made on the chemical (long-term feeding tests required).
(d) Results of tests on the amount of residues remaining, including description of the analytical method used.
(e) Practical method for removing residues which exceed any proposed tolerance.
(ii) Fixation of acceptable daily intake of each pesticide- A joint meeting of the WHO and FAO in 1963 prescribed the values of acceptable daily intake of a number of pesticides on the basis of all available data.
(iii) Fixation of minimum time lag between application of pesticide and harvest of the crop. In the UK a working party suggested restrictive conditions of pesticide use, viz., use on specified crops only, maximum rates of application, and minimum intervals between the last application and harvest.
(iv) Banning or discouraging the use of certain pesticides. This has been suggested by Cook’s Committee (UK) for certain insecticides.
B. Suggestions for India:
(i) India should adopt No. (i), enforced by law in USA, and fix tolerance limits for each pesticide on each commodity.
(ii) It should fix the minimum time lag between application of pesticide and harvest, and this should be advisory so that cultivators may be reasonably sure that their produce will comply with legal regulations for tolerance limits.
(iii) For the acceptable daily intake no specific action is needed separately because these values are considered to be applicable to the human species in general.
(iv) Banning the use of an insecticide may be done only when there are enough scientific data for recommending a firm decision and there is a prima facie for it. For example, there can be hardly any difference of opinion on the necessity of extreme precautions against direct contamination of food grains and fresh vegetables and indirect contamination of milk.
(v) It should also give such advice as may be necessary for reducing hazards of skin contamination of cultivators during weeding, picking, harvesting and handling treated harvest.
It should be easy to recommend, on the basis of existing knowledge and common sense, precautions against operational hazards from pesticides right up to the application of pesticides. It is, however, the hazards from pesticide residues which have caused the greatest concern all over the world. For recommending precautions against residue hazards many carefully collected data are needed, but these are not available for Indian conditions.
Hence, only the most obvious precautions can be recommended at present. It is necessary to constitute certain standing bodies and to create certain organizational facilities for keeping constant vigil over pesticide hazards and for collecting necessary data for formulating rational precautions from time to time.
1. For chemical treatment of vegetables, harvesting of which continues for a good part of the season when pesticidal operations have to be carried out, only safer insecticides of plant origin should be used. Even with readily breaking down organo-phosphorus insecticides fatal accidents may occur sometimes because of harvesting and consumption soon after spraying, and it may be difficult to ascribe these to pesticide poisoning because by the time the legality of getting the residues is complied with the insecticides may break down into non-toxic compounds.
It is necessary to make legal provisions to collect samples from vegetable markets to have them quickly analysed, and to take necessary action against those found guilty.
2. Special precautions are necessary to check insecticide contamination of cereals, pulses and tubers (potato, sweet-potato), which are consumed in large quantities and to preserve which it is tempting to use insecticides. Hence, it is necessary to discourage this practice as much as possible and to make legal provisions to collect samples from the market for quick analysis and prompt legal action. This is particularly necessary because the alternative fumigation methods are there to check infestation of stored products.
3. Efforts should be intensified to increase the production of pyrethrum, for it provides the safest insecticide so far known. An argument against pyrethrum is its high cost and non-availability. On the other hand, producers of pyrethrum complain of insufficient interest in its use.
A conference held in Jammu in 1961 passed the following resolutions:
a. “It was unanimously felt while the users of pyrethrum are not sure of the supply of pyrethrum in sufficient quantity and at competitive rates, the producers of pyrethrum are apprehensive that they may not find proper demand for their produce. When the question of enhancing the pyrethrum production is discussed, doubts are often expressed whether pyrethrum will be able to compete with synthetic products. On the other hand, when the question of using pyrethrum on large scale is discussed, the argument is put forth that pyrethrum is not available and is very costly. It is, therefore, fully established that on its intrinsic merits, pyrethrum is preferable to most of the synthetics especially in the field of storage of food grains. Both pyrethrum industry and food grain storage are suffering mainly because of a lack of proper co-ordination between the producers and users of pyrethrum”.
b. “It was recalled that due to the fact that the producers did not find proper market, the cultivation of pyrethrum had to be given up in Assam and in the Nilgiris and even in Kashmir area under pyrethrum cultivation had to undergo considerable reduction. On the other hand, it is mainly because of the non-availability of pyrethrum in sufficient quantity and at remunerative price that toxic chemicals like Lindane, Malathion, etc., are being recommended for use in the storage of food grains.”
c. “Discussion on various other plant products showed that what has been stated above about pyrethrum is also applicable in various degrees to several drugs of plant origin. It was, therefore, unanimously resolved to recommend the formation of an All-India Co-ordination Council for the Production and Utilisation of Pyrethrum and other such plant products. This Council should be entrusted with the task of maintaining a close liaison between the producers and users of pyrethrum and other such products to ensure a proper supply of pyrethrum to the users and proper market to the producers.”
4. Specific legal provisions should be made for setting up tolerance limits of pesticides, as has been in the USA. The Central Committee for food standards which, it is understood, has made some attempt for recommending tolerance limits for certain chemicals is not the appropriate body because tolerance limits are to be fixed not only for food grains but also for vegetables, fruits and even fodder. The standing committees and the organizational facilities needed for this and related purposes are indicated below.
5. A standing Insect Pest and Disease Control Advisory Committee (IPDCAC) should be set up somewhat on the lines of the Federal Pest Control Review Board of the USA. This committee should act on the lines of the American Board and on the Agricultural Pesticides Approval Scheme of the UK. It should periodically examine all methods of pest control recommended by various workers in the country and should officially approve those which show optimum combination of efficiency and safety.
The committee should consist of research and extension workers in almost equal numbers. It should periodically invite recommendations for pest control from various workers in the country, consider them, and issue a list of approved methods of pest control from time to time. This should be mainly on the basis of efficiency of the pest control methods recommended, but the committee should take into consideration the hazards also.
It should fix and periodically review the minimum time that must elapse between the last application of insecticide and the harvest of different crops to ensure with reasonable certainty that the residues will remain within tolerance limits.
6. A standing interdepartmental Pesticide Hazards Committee (PHC) should be constituted on the lines of the British Advisory Committee on Poisonous Substances used in Agriculture and Food Storage.
This committee should carry out mainly the following functions:
(a) To fix and periodically review tolerance limits of various insecticides in various commodities of food, fodder, etc.
(b) To determine and periodically review the hazards from grazing by animals and skin contamination in men and animals during agricultural operations in treated fields.
(c) To determine and periodically review all operational hazards in the manufacture, distribution, dilution, handling, etc. of insecticides.
(d) To determine and periodically review the contamination of the environment by insecticidal fumes from factories and refuse let out into rivers, etc.
(e) To keep a vigil on the new types of hazards arising from the introduction of new chemicals or new forms of application.
7. The functions of and the interrelations between, the IPDCAC and the PHC should be clearly spelt out.
The interrelations should be as follows:
The IPDCAC should first finalize its selection of control measures purely on the basis of their efficiency, and thereafter the PHC should scrutinize these selected methods in respect of hazards. Finally, the IPDCAC should consider the recommendations of the PHC and finalize its own recommendations for extension workers and pest control personnel on the basis of optimum combination of efficiency and safety.
8. There should be a legal provision that only those pest control measures shall be carried out which have been approved by the IPDCAC.
9. An effective monitoring organization for proper assessment of pesticide residues should be established.
10. Agricultural operations are generally intermingled. For example, chemical spraying against pests, diseases and weeds may get intermingled with operations like weeding and repeated harvesting of crops like cotton. It is necessary to save the workers from contamination with pesticide residues on crops. The extent of such contamination should be studied and necessary precautions taken against such hazards.
11. The nature of protective clothing should be specified, and there should be legal provision to have the items periodically checked. The PHC should examine the various types of protective clothing available in the country from time to time. For example, a medical engineering firm put forth gasmasks and certain other equipment for the use of the workers in the pesticide industry and research institutions. These devices should be allowed to be marketed only after they have been approved by the PHC.