Safety in insecticide usage
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Romeo S. Rejesus
Belen M. Rejesus
"Safety First, The life You Save May Be Your Own" goes the standard caution is risky or dangerous activities and work situations. Yet daring individuals defy such warning, perhaps out of ignorance, expediency, carelessness and belief in the "macho" ego.
Defiance of these basic safety rule results in death and disability in the farm, industrial plants, on the road and other forms of travel, and even at home. Of particular interest to us is safety in handling pesticides, a toxic material in whatever form. There is no substitute for cure in handling insecticides.
It is important to understand some basic principles related to safe usage of insecticides. The term "safety" means different things to different people and its meaning differs mostly with each situation in which it is used; at best it is a very relative term. For purposes of those of us who deal with insecticidal chemicals, it involves the concept of hazard or risk, i.e. the likelihood of some adverse effect resulting from certain sets of circumstances, including the approved use of a chemical or any possible misuse.
Hazard in the use of pesticides may be defined as the likelihood that injury could result from the use of or exposure to the product, Often, hazard and toxicity are considered by many people to mean one and the same.
Toxicity measures the actual harm which results if the product is absorbed while hazard takes into consideration the likelihood of contact or absorption. In many instances toxic substances are handled for long periods with out any harm simply because precautions have been taken to prevent contact or absorption, hence hazard become negligible.
In order to better appreciate safety of insecticide handling and usage, it is important to consider the following hazards and take the necessary precautions:
A. Acute Hazards
a. Oral intake
b. Dermal Absorption
c. Inhalation-There is a risk of absorption through the lungs
B. Chronic Hazards
These can result from faulty practices repeated over extended periods:
These are mainly direct hazards affecting men. Hazards to the environment is an important consideration particularly its negative ecological impact. For our purpose we will concentrate on the dangers to man, the applicator and consumers. It does not necessarily mean that insecticides are bad and should not be used - far from that.
Realizing these hapards, let us now consider the corresponding precautionary measures to counteract these risks.
Toxicological studies are conducted to determine the threshold limit of a chemical which an animal or human is capable of handling without significant biological effects. The usual beginning in any toxicological evaluation is the assessment of the acute toxicity i.e., the effects of a single dosage of the chemical. The general technique is the determination of the LD50 (the dosage necessary to produce death or reproducible effect in 50% of the animal population tested). The compound is administered on a weight/weight basis (milligram or gram of compound per kgm of body weight of test animals) in a suitable solvent or suspension system. This is evaluated by acute tests, orally (AO) or dermally (AD), chronic oral tests (CO), vapor toxicity tests (VA) and chronic vapor tests (VC) or inhalation tests (IT).
Insecticides can be classified according to their toxicity based on the LD50 values:
1. High toxic
AO LD50 = 0-50 mg/kg
AD LD50 = 0-200 mg/kg
IT LC50 = 0-2000 ug/l
Danger, skull and crossbones and poison on label.
2. Moderately toxic
AO LD50 = 51-500 mg/kg
AD LD50 = 201-2000 mg/kg
IT LC50 = 2,0001-20,000 ug/l
Warning on label.
3. Slightly toxic
AO LD50 = 501-5000 mg/kg
AO LD50 = 2,000-20,000 mg/kg
IT LC50 = more than 20,000 ug/l
4. Relatively nontoxic
AO LD50 = 5000 + mg/kg
AD LD50 = 20,000 + mg/kg
AD LC50 = of some of the common insecticides
Generally, the insecticides used in stored product treatment are of low mammalian toxicity (Table 1) and are in a formulation that is likely to be effective against the species involved, persistent for the required period of time under given storage conditions and will not alter the flavor, color of the stored commodity.
The Joint FAD/WHO Codex Alimantarius Commission was established to implement the Joint FAD/WHO Food Standards Programme. The purpose of the Programme is to elaborate international standards for food aimed at protecting the health of the consumer, ensuring fair practions in the food trade, and by their acceptance by governments resulting in the harmonization of national food legislations, thereby facilitating international trade. The food standards incorporate provisions in respect to food hygiene, food additives, pesticide residues, other contaminants and methods of analyis and sampling. The Codex has a committee which establishes maximum limits for pesticide residues in specific food item or group of food, Table 4 presents both the Codex recommended residues and "guideline [eve". The former is intended to assist administering authorities, eventhough acceptable daily intakes have not been established for the individual products.
Table 1. LD50 of some insecticides used for stored product protection'
mg/kg body wt. rat)
|Malathion***||885 - 2800|
|Pirimiphos methyl**||2050 - 2300|
|Chlorpyrifos methyl**||041 - 2140|
|Tetrachlorvinphos*||4000 - 5000|
|Bromophos*||3750 - 7700|
|Dichlorvos**||25 - 170|
|Diazinon*||66 - 600|
|Fenitrothion*||250 - 670|
|Lindane* *||76 - 200|
|DDT*||87 - 500|
|Carbaryl*||307 - 986|
|Alletrin**||680 - 1000|
|Pyrethrine**||200 - 2600|
1 From Kenaga and End 1974.
2 Usage summarized from Champ and Dyte 1971.
* Occasional use
** Moderate use
*** Intensive use
Guidelines for Safe Pesticide Use
Although the use of insecticides has its undesirable side effects (upset biotic balance, leave harmful residues, and insects develop resistance), its use must go on until a better control method has been found. Thus, there is a need for precautionary measures in its use so that the harmful effects can be minimized.
A. Precautionary Measures
1. Never apply more or less than what the pesticide label specified time of application and rates at the specified time of application and follow safety precautions.
2. Store pesticides under lock and key, away from children, pets, food and anything or anybody who does not understand how dangerous they can be.
3. Never leave pesticides unlabeled or misleadingly labeled. Better still, keep them in their original containers, whenever practicable.
4. Do not smoke or eat while handling pesticides. Protective clothing, gloves and masks are desirable when one works closely with them. Discard contaminated clothing and empty packages and always wash thoroughly after handling such toxic chemicals.
5. Never re-use pesticide containers for purposes such as for storing food or water. No one is ever sure that residues will not be there.
6. All poison baits should be clearly marked as dangerous. When baits containing acute poisons are laid, everyone should be excluded from the area; and when treatment is finished all uneaten baits should be collected and burnt along with any rodent corpses found during and after treatment.
7. If symptoms of poisoning (nausea, rashes, vomiting), occur, stop working and run, don't walk, to the nearest antidote. The life you save may be your own.
8. In general, repeated and prolonged contact with any insecticide is to be avoided especially if it is in the form of dusts, mists, vapours, or concentrated formulations.
B. Curative Measures
1. Curative measures - Spillage, breakages and other such accident cannot be entirely ruled out in insecticide use. The following therefore are geared towards minimizing poisonous effects:
a. Spilled materials are immediately wiped with rags which are then buried. Do not burn.
b. Thoroughly wash with soap and water skin that has been in contact with pesticides. Contaminated clothing should be washed thorouhly before use or burned depending on the degree of contamination.
c. If pesticide has been swallowed, induce vomiting and immediately seek medical attention.
d. In cases of dizziness or nausea in the use of pesticides, stop work immediately and get medical attention.
C. First Aid in Case of Energency
Call your physician immediately in case of emergency.
1. Group I - Arsenicals, Organochlorines, Fluorines, Nicotine.
a. For ingestion - Induce vomiting by inserting a finger down the throat of the patient or give a tablespoon of salt in a glass of warm water. Repeat until vomit fluid is clear then give two tablespoons of Epson salts or milk of Magnesia in water and plenty of milk or water. Have the victim lie down and keep him quiet. Keep him warm, use external heat (blanket, hot water bottle). If nicotine is involved, artificial respiration may be needed. Phenobarbital should be given by a physician to control convulsions.
b. External - Wash exposed areas with soap and water.
2. Group II - Di Nitro Compounds
Table 3. Estimates of odor threshold and maximum exposures (ppm) safe for human subjects of some fumigants.
|Single Exposure||Approx. Odor Threshold (ppm)|
|No more than once a week|
|7 hours||1 hour|
|1. Methyl bromide||1,2,3||100||200||none|
|3. Ethylene dibromide||1||50||200||25|
|4. Ethylene dichloride||1||200||1000||50|
|5. Ethylene oxide||1||150||500||300 -1500|
|6. Carbon disulfide||1||100||200||30 - 60|
|7. Carbon tetrachloride||1, 3||50||300||60 - 70|
|8. Propylene oxide||1||400||1000||115 - 350|
|9. Dowfume EB-Sb||1||75||300||25|
a1 - Commodity; 2 - Space; 3 - Structure.
b Mixture of fumigant No. 4, 5 and 7.
c Mixture of fumigant No.6 and 7.
Table 4. The maximum residue limit (ppm) for cereal grains.
|Carbaryl||-||-||3 T||10 T||5 T|
|Chlorpyrifos methyl||-||10 T||0.1 T||10 T||10 T|
|Fenitrothion||10 T||10 T Hulled||-||-|
|& in Husked|
|1 T polished||-||-|
|Methyl Bromide||50 GL|
|Piperonyl Butoxide||20 T||-||-||-||-|
|Pirimiphos methyl||-||7||2 T Hulled|
|10 T in Husked|
|1 T in Polished|
T - Codex Tolerance
GL - Guideline Level
a. For ingestion - Speed is important if body temperature rises, cool with cold presses. Give tablespoon of baking soda in warm water. Repeat until vomit fluid is clear.
b. External - wash with soap and water.
3. Organic Phosphates and Carbamates
a. For ingestion - induce vomiting by inserting finger down throat or by taking tablespoon of salt in glass of warm water. Atropine (0.1 gr.) and oxygen should be administered by a physician. Other agents such as 2-PAM (pyridine-2-aldoxine), DAM (dracetylmonoxime) could be administered by a physician for organophosphate poisoning but never for carbamate poisoning.
b. External Wash with soap and water and swab with ethyl alcohol.
a. In case of poisoning of acute poisons, zinc sulphide, through inhalation or accidental consumption of poison baits, swift action should be taken. Mustard emetic should be immediately administered to induce vomiting. When the vomiting stops, give 6 gms potassium permanganate dissolved in glass of warm water. This will produce insoluble copper sulphide. After that give a purgative - one tablespoon of Epsom salt in water. Call doctor immediately.
b. In case of accidental consumption of this poison, call the physician immediately. Vitamin K administration and blood transfusion are recommended. Never give morphine, baribtuates or tranquilizers. In all cases, do not induce vomiting if patient:
All pesticides must be considered in some way potentially harmful to man and should only be used by trained persons.
In particular, concentrated insecticides, rodenticides and fumigants must be handled with extreme caution. Washing water must be available to operators.
Protective clothing should be available. Rubber gauntlet gloves should be worn when handling concentrated insecticides. Face masks must always be worn when insecticide dusts and sprays are mixed or being applied. They should also be worn when rodenticide dusts or concentrates are being used.
For fumigation involving methyl bromide, full face respirators with the appropriate canisters must be used. For phosphine fumigations, respirators with appropriate canisters must be available for all but the smallest trements (e.g. single bags). In all but the smallest fumigation treatments, two operators should be present with one designated as in-charge.
When mixing concentrated insecticides with water or other diluent, a spoon or other implement must be used. Never use the hands to pick-up concentrated insecticide. During this operation, especially if the store room is small, always leave the door open to prevent a build-up of dust or fumes. Lids should be replaced on concentrate concentrate containers immediately after use.
Care must be taken to ensure that correct application of insecticides is undertaken particularly where insecticides are added directly to food commodities.
ALWAYS READ THE LABEL ON THE CONTAINER AND FOLLOW THE MANUFACTURERS INSTRUCTIONS.
Application equipment for sprays and fumigants must be checked before the start of treatment.
Rodenticides must be placed in locations that are not accessible to domestic or farm animals. Use bait boxes where where possible.
All buildings or stacks of products being fumigated must be clearly labelled. Personnel should not continue to work in the building whilst a fumigation is being carried out and should not resume work there until tests have shown it is safe to do so.
All pesticides should be stored in clearly labelled containers in a safe place under lock and key. Storage should not be in the main warehouse where food is stored, but in a separately designated room. Pesticides should not be stored in or adjacent to living quarters. Storekeepers in charge of pesticides must be properly trained. They must not eat, drink or smoke in pesticide stores. All pesticides must be checked into and out of stores and a record with full details kept. Large stocks of pesticides are best avoided since they can deteriorate quickly at high temperatures and humidities. Efforts should be made to ensure that sufficient pesticides for one season only are stored wherever possible.
1. Snelson, J.T. 1985. Safety considerations in insecticide usage in grain storage. Proc. In Pesticides and Humid Tropical Grain Storage System. International Seminar, Manila, Philippines.27-30, May 1985. ACIAR, NAPHIRE and ASEAN Food Bureau. pp. 87-100.
2. DAVies, F.B. and Freed, V.H. (eds.) (undated). An Agromedical Approach to Pesticide Management: Some health and environmental considerations. Consortium for International Crop Protection. 379 pp.
3. Anon. 1982. The safe use of Pesticide. In International Course on Seed Technology for Vegetable Crops. Pest Control. Tropical Products Institute, London Rd., Slough, UK. p. 98.
1. The Joint FAD/WHO Food Standards Programme and the Codex Alimentarius Commission
The Joint FAD/WHO Codex Alimentarius Commission (the Commission) was established to implement the Joint FAD/WHO Food Standards Programme. Membership of the Commission comprises those Member Nations and Associate Members of FAO and/or WHO which have notified the Organizations of their wish to be considered as Members. By April 1984, 122 countries have become Members of the Commission. Other countries which participate in the work of the Commission or of its subsidiary bodies in an observer capacity are expected to become Members in the near future.
The purpose of the Joint FAD/WHO Food Standards Programme is to protect the health of consumers and to ensure fair practices in the food trade; to promote coordination of all food standards work undertaken by international, governmental and non-governmental organizations; to determine priorities and initiate and guide the preparation of draft standards through and with the aid of appropriate organizations; to finalize standards and following their adoption, publish them in a Codex Alimentarius either as regional or world-wide standards.
For further information concerning the work and procedures of the Commission, readers should refer to the Procedural Manual of the Codex Alimentarius Commission (5th Edition) which also contains definitions of terms for the purpose of the Codex Alimentarius. In addition, Volume I of the Codex Alimentarius (CAC/VOL.I - Ed. 1) includes general information about a wide variety of aspects of the work of the Commission.
2. The Codex Committee on Pesticide Residues
The Codex Committee on Pesticide Residues (CCPR) is an inter-governmental body which advises the Commission on all matters relating to pesticide residues. It meets every year and submits reports ("ALINORM" reports) to the Commission. The CCPR has the responsibility:
(a) to establish maximum limits for pesticide residues in specific food items or in groups of food;
(b) to establish maximum limits for pesticide residues in certain animal feeding stuffs moving in international trade where this is justified for reasons of protection of human health;
(c) to prepare priority lists of pesticides for evaluation by the Joint FAD/WHO Meeting on Pesticide Residues (JMPR);
(d) to consider methods of sampling and analysis for the determination of pesticide residues in food and feed;
(e) to consider other matters in relation to the safety of food and feed containing pesticide residues; and
(f) to establish maximum limits for environmental and industrial contaminants showing chemical or other similarity to pesticides, in specific food items or groups of food.
The CCPR relies on data supplied by Member Governments and on the recommendations and evaluations of the Joint FAD/WHO Meeting on Pesticide Residues (JMPR). The conclusions of the JMPR are submitted to the CCPR for consideration and further elaboration in accordance with the Commission's procedures. After adoption by the Commission, the maximum limits for pesticide residues are submitted to governments for acceptance in accordance with the Procedures for the Acceptance of Codex Maximum Residue Limits laid down by the Commission (see Section 1.7 below).
3. The Joint FAD/WHO Meeting on Pesticide Residues
The Joint FAD/WHO Meeting on Pesticide Residues (JMPR) is composed of expets who serve in a personal capacity. The JMPR evaluates pesticide residues on the basis of all available data supplied by Governments and Industry and, where appropriate, establishes "acceptable daily intakes" (ADls) and recommends maximum limits for pesticide residues in food. The conclusions of the experts are published in joint FAD/WHO reports (Ret: WHO Techn. Rep. Ser. or FAO Plant
Production and Protection Paper Series). Toxicological and residue data are summarized in publications under the series "Evaluations of Some Pesticide Residues in Food" published by FAO. The views and recommendations of the FAD/WHO Experts are taken by the CCPR as the basis for reaching decisions concerning the safety or otherwise of residues of pesticides in food and as the basis on which the CCPR can judge whether such residues are unavoidable in accordance with "Good Agricultural Practice".
4. Procedure for the Elaboration of Codex Maximum Limits for Pesticide Residues
Codex maximum residue limits are elaborated in accordance with a Procedure which affords full participation by Governments and International Organizations, either directly (i.e. at Sessions of the Codex Alimentarius Commission (Steps 5 and 8) or at Sessions of the Codex Committee on Pesticide Residues (Steps 4 and 7) ). The Procedure also allows countries to submit to the Commission (at Step 5) a statement in writing on any impact the draft Codex maximum residue limits may have on their economic interests. Furthermore, comments in writing on the draft Codex maximum residue limits are routinely invited at Steps 3 and 6 of the Procedure. Details of the Codex Procedure are given in the Procedural Manual of the Codex Alimentarius Commission (5th Ed). A summary of the Procedure is given below:
|1,2||In practice, Steps 1 and 2 are omitted.|
|3||The maximum residue limits (MRLs recommended by the JMPR - see Section 1.3 - are sent to Governments and International Organizations for comments.|
|4||The MRLs are considered by the CCPR (see Section 1.2) in the light of written comments received.|
|5||The MRLs are considered by the Commission (see Section 1.1). Economic Impact Statements may be submitted in writing at this Step.|
|6||The MRLs are sent to Governments and International Organizations for comments.'|
|7||The MRLs are considered by the CCPR (see Section 1.2) in the light of written comments received.'|
|8||The MRLs are considered by the Commission and adopted as Codex MRLs (see Section 1.1). Governments may submit proposals for amendment in writing.|
It should be noted that temporary maximum residue limits are no longer adopted by the Commisssion as Codex maximum residue limits. Any existing temporary Codex maximum residue limits are those which were adopted by the Commission previously or maximum residue limits where the "acceptable daily intake" estimated by the JMPR has been converted into a 'temporary acceptable daily intake'.
It should also be noted 'Guideline Levels' (see definitions and Part 3 of the Guide) are not processed beyond Step 4 of the Codex Procedure. Guideline Levels do not constitute Codex recommendations and are published only for the information of Governments, in the expectation that the JMPR will set an 'acceptable daily intake' or 'temporary acceptable daily intake' for the pesticides and their residues concerned.
5. Acceptance of Codex Maximum Limits for Pesticide Residues
Codex maximum residue limits, i.e. those marked "CXL", in the Guide (Part 2) are submitted to all Member Nations and Associate Members of FAO and/or WHO for acceptance in accordance with the Procedure for Acceptance of Codex Maximum Limits for Pesticide Residues contained in paragraph 6 of the General Principles of the Codex Alimentarius, under which the maximum limits may be accepted in one of the three following ways: full acceptance, limited acceptance, target acceptance. The General Principles of the Codex Alimentarius are contained in the Procedural Manual of the Codex Alimentarius Commission (5th Ed).
In interpreting the General Principles of the Codex Alimentarius, it should be recognized that the maximum limits apply to residues of pesticides in food and do not imply recommendations concerning the use of the pesticides. A country accepting a maximum limit for a pesticide residue in any of the ways set forth in paragraph 6 of the General Principles in not thereby prevented from restricting or prohibiting the use of that pesticide, nor is it compelled to permit the use of that pesticide if it is not required in its agriculture or if its use is not desirable for environmental reasons or for other reasons such as the protection of operators.
Letters or instruments of acceptance should specify the type of acceptance in respect of each Codex maximum limit and to indicate all necessary information. To assist Governments in notifying their acceptance or otherwise, a copy of a suitable Acceptance Form relating to the maximum limits is made available.
Governments which are unable to accept a particular Codex maximum residue limit in one of the three ways mentioned above may, nevertheless, be in a position to indicate whether products conforming to that maximum limit may be distributed freely within their territorial jurisdictions, as provided for under paragraph 6.B of the General Principles or may be permitted to be distributed subject to certain specified conditions. Governments are urged to take this possibility into account in cases where full, target or limited acceptance cannot be given.
The Codex Committee on Pesticide Residues is elaborating guidelines on regulatory practices to assist Governments in accepting Codex maximum limits for pesticide residues as soon as completed, the Guidelines will be distributed to Governments.
The Joint Office of the FAD/WHO Food Standards Programme, FAO Headquarters, Rome, will be pleased to provide to the appropriate authorities in each country any information, explanation or assistance that may be required with respect to the Codex maximum residue limits, to the Codex acceptance procedure or to the activities of the Codex Alimentarius Commission in general.
Up-to-date and full details of acceptances and other responses from Governments as at September 1983, have been published in the Codex Alimentarius, Summary of Acceptances Part II - Codex Maximum Limits for Pesticide Residues.
DEFINITION OF TERMS USED BY THE CODEX
The definitions of terms given below are intended for the purposes of the Codex Alimentarius and other Codex publications, such as the present Guide. Governments may wish to use different definitions. It should be noted that the definitions have been reviewed by the Codex Committee on Pesticide Residues and will be considered by the 16th Session of the Codex Alimentarius Commission.
(a) Animal Feed means harvested fodder crops, by-products of agricultural crops and other products of plant or animal origin which are used for animal feeding and which are not intended for human consumption.
(b) Pesticide means any substance intended for preventing, destroying, attracting, repelling, or controlling any pest including unwanted species of plants or animals during the production, storage, transport, distribution, and processing of food, agricultural commodities, or animal feeds or which may be administered to animals for the control of ectoparasites. The term includes substances intended for use as a plant-growth regulator, defoliant, dessicant, fruit thinning agent, or sprouting inhibitor and substances applied to crops either before or after harvest to protect the commodity from deterioration during storage and transport. The term normally excludes fertilizers, plant and animal nutrients, food additives, and animal drugs.
Explanatory Note: "Agricultural commodities" refers to commodities such as raw cereals, sugar beet, and cottonseed which might not, in the general sense, be considered food.
(c) Pesticide Residue means any specified substances in food, agricultural commodities, or animal feed resulting from the use of a pesticide. The term includes any derivatives of a pesticide, such as conversion products, metabolites, reaction products, and impurities considered to be of toxicological significance.
Explanatory Note: The term "pesticide residue" includes residues from unknown or unavoidable sources (e.g., environmental), as well as known uses of the chemical.
(d) Good Agricultural Practice in the Use of Pesticides (GAP) is the officially recommended or authorized usage of pesticides under practical conditions at any stage of production, storage, transport, distribution and processing of food, agricultural commodities, and animal feed bearing in mind the variations in requirements within and between regions, 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.
Explanatory Note: The "officially recommended or authorized usage of pesticides" is that which complies with the procedures, including formulation, dosage rates, frequency of application and preharvest intervals, approved by the national authorities.
(e) Acceptable Daily Intake (ADI) of a chemical is the daily intake which, during an entire lifetime, appears to be without appreciable risk to the health of the consumer on the basis of all the known facts at the time of the evaluation of the chemical by the Joint FAD/WHO Meeting on Pesticide Residues. It is expressed in milligrams of the chemical per kilogram of body weight.
Explanatory Note: For additional information on ADls relative to pesticide residues refer to the Report of the 1975 Joint FAD/WHO Meeting on Pesticide Residues, FAO Plant Production and Protection Series No. 1 or WHO Technical Report Series No. 592.
(f) Temporary Acceptable Daily Intake (TADI) is an acceptable daily intake established for a specified, limited period to enable additional biochemical, toxicological or other data to be obtained as may be required for estimating an acceptable daily intake.
Explanatory Note: A TADI estimated by the Joint FAD/WHO Meeting on Pesticide Residues normally involves the application of a safety factor larger than that used in estimating an ADI.
(g) Maximum Residue Limit (MRL) is the maximum concentration for a pesticide residue resulting from the use of a pesticide according to good agricultural practice that is recommended by the Codex Alimentarius Commission to be legally permitted or recognized as acceptable in or on a food, agricultural commodity, or animal feed. The concentration is expressed in milligrams of pesticide residue per kilogram of the commodity.
Explanatory Note: The "recognized as acceptable" is intended to accommodate Member Countries which, under national legislation, do not use MRLs as legal limits. An MRL is principally based on supervised trials carried out under varying conditions of climate and pest control needs.
(h) Extraneous Residue Limit (ERL) refers to a pesticide residue or a contaminant arising from environmental sources (including former agricultural uses) other than the use of a pesticide or contaminant substance directly or indirectly on the commodity. It is the maximum concentration of a pesticide residue or contaminant that is recommended by the Codex Alimentarius Commission to be legally permitted or recognized as acceptable in or on a food, agricultural commodity or animal feed. The concentration is expressed in milligrams of pesticide residue or contaminant per kilogram of the commodity.
Explanatory Note: The term "practical residue limit" has been used for residues in food from unavoidable sources and in food of animal origin arising from residues in animal feed. This term, which had led to much confusion, was abandoned. Residues in food of animal origin that are controllable by farming practices are now covered by MRLs. Residues from unavoidable sources are covered by ERLs which are usally based on residue data from food monitoring programmes.
(i) Temporary MRL (TMRL) or Temporary ERL (TERL) is an MRL or ERL established for a specified, limited period and is recommended under either of the following conditions:
1. where a temporary acceptable daily intake has been estimated by the Joint FAO/WHO Meeting on Pesticide Residues for the pesticide or contaminant of concern; or
2. where, although an acceptable daily intake has been estimated, the good agricultural practice is not sufficiently known or residue data are inadequate for proposing an MRL or ERL by the Joint FAD/WHO Meeting on Pesticide Residues.
Explanatory Note: TMRLs and TERLs are not to be advanced further than Step 7 of the Codex Procedure.
(j) Guideline Level is used to assist authorities in determining the maximum concentration of a pesticide residue resulting from a use reflecting good agricultural practice but where an acceptable daily intake or temporary acceptable daily intake for the pesticide has not been estimated or has been withdrawn by the Joint FAD/WHO Meeting on Pesticide Residues. The concentration is expressed in milligrams of pesticide residue per kilogram of the commodity.
Explanatory Note: Guideline Levels are not to be advanced further than Step 4 in the Codex Procedure and are to be listed separately from MRLs and TMRLs in Codex documents.
(k) Limit of Determination is the lowest concentration of a pesticide residue or contaminant that can be identified and quantitatively measured in a specified food, agricultural commodity! or animal feed with an acceptable degree of certainty by a regulatory method of analysis.
(l) Regulatory Method of Analysis is a method that has been validated and can be applied using normal laboratory equipment and instrumentation to detect and determine the concentration of a pesticide residue or contaminant in a food, agricultural commodity or animal feed for purposes of determining compliance with a maximum residue limit or extraneous residue limit.
Explanatory Note: for more information on regulatory methods of analysis and their application, refer to Recommendations for Methods of Analysis for Pesticide Residues and Codex Guidelines on Good Analytical Practice.
(m) Intake Study is a study designed to measure or estimate actual dietary exposures of consumers to pesticide residues or contaminants in order to compare such exposures to the acceptable daily intakes for pesticides or contaminants.
Explanatory Note: For more information on intake studies, refer to Guidelines for the Study of Dietary Intakes of Chemical Contaminants prepared by the Joint FAD/WHO Food Contamination Monitoring Programme (WHO-EEPI83.53, FAOESN/M ISC/8312).
GUIDELINES ON GOOD AGRICULTURAL PRACTICE IN THE USE OF PESTICIDES
The main purpose of this document is to indicate guidelines on the use of pesticides on a general basis and to encourage the use of more effective and/or less persistent pesticides so as to reduce the amount of residues in food of plant or animal origin, in animal feed, and in the environment. These guidelines are intended for use by administrators, specialists and advisory agencies. No attempt will be made to elaborate recommendations for the use of individual pesticides and their formulations. It should be emphasized that due to differences in pests, -pest population, commodities, climate and geographical location, it is not possible to propose universal recommendations for the use of specific pesticides against specific pests. It should also be remembered that not all countries have uniform capabilities for the development and implementation of detailed guidelines for the use of pesticides. Therefore, only general guideline practices can be suggested for the use of pesticides, and the details of use will require development of information within the Member countries. The important issue is, however, to try and eliminate disturbing side-effects of certain pesticides or certain applications.
A first basis for general guidelines is provided by the Codex definition of the concept of "good agricultural practice in the use of pesticides", which is as follows:
"Good agricultural practice in the use of pesticides is the officially recommended or authorized usage of pesticides under practical conditions at any stage of production, storage, transport, distribution and processing of food, agricultural commodities and animal feed, bearing in mind the variations in requirements within and between regions, 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".
Explanatory Note: The "officially recommended or authorized usage of pesticides" is that which complies with the procedures, including formulation, dosage rates, frequency of application and pre-harvest intervals, approved by the national authorities.
1. Noting that the occurrence of unintentional residues in a number of food items and animal feedstuffs is partly a result of environmental contamination, the Meeting recommends that efforts be made to discover the sources of such contamination and, where possible, to eliminate them, in order to reduce the background level of pesticide residues.
2. In view of the concern over the extent of the use of certain persistent pesticides, the Meeting recommends that they be replaced, wherever possible, by pesticides, the residues of which are less undesirable toxicologically.
The emphasis in these recommendations is clearly on the desirability of making a conscious effort to replace certain pesticides by alternative chemicals, which are preferable from the food or environmental health point of view. The importance of reducing residues in animal feed has again been emphasized by a recommendation of the 1969 Joint Meeting (WHO Technical Report Series No. 458):
"Because some compounds currently in use as seed protectants are highly toxic to humans, and their uses can result in the occurrence of unintentional residues, the need to develop safer substitutes was emphasized. In the meantime, every effort should be made to reduce the contamination of commercial grain and animal feeds to the minimum and to undertake surveys to ensure that directions are being observed by farmers and others concerned with the handling of treated seeds".
Further discussions during the 1972 Joint Meeting have indicated the desirability of recommending limits for pesticide residues in animal feed (WHO Technical Report Series No. 525):
"In recognition of the fact that residues in animal products can result from residues in feed and that such animal feeds enter into commerce, the Meeting felt it would be appropriate to consider data and to make recommendations on residues in such animal feeds".
It must be recognized that the policy with respect to pesticide regulations or control measures has in many countries followed trends similar to those indicated in the FAD/WHO recommendations. As a consequence, restrictions in the use of certain pesticides have been implemented. It would, therefore, seem useful to translate the principles of the recommendations into terms of general guidelines referring to the particular aspects of pesticide usage.
Before attempting to construe general guidelines from existing principles, such as are laid down in the definition of good agricultural practice, and in the various recommendations from the FAD/WHO Joint Meeting on Pesticide Residues, it may be useful to consider briefly the present pesticide situation as background against which further considerations should be judged. Without being exhaustive, the following summary could serve such purpose:
The use of pesticides for agricultural, veterinary, public health, domestic and industrial purposes has:
(a) ensured a better protection of harvest against unpredictable losses caused by plant diseases and pests;
(b) in general improved both the quantity and quality of food;
(c) decreased the extent of vector-borne and other diseases in humans and animals.
For the foreseeable future agricultural pesticides will continue to be required in the production, transportation and storage of food, feed and fibre. However, most pesticides are derived from, or produced through the use of non-renewable world resources. Wastage in their use should be avoided as part of an overall global effort to conserve these resources, maximize their effectiveness and minimize unnecessary environmental pollution.
Apart from occupational accidents and gross misuse, the regular use of pesticides has resulted in a number of undesirable side-effects, partly attributable to occasional indiscriminate applications, partly due to undoreseen biological effects.
This situation has prompted developments which can be briefly described as follows:
(a) research on alternative methods of pest control, and introduction of these wherever technically possible and economically feasible;
(b) introduction of alternative pesticides with greater safety and suitability;
(c) more adequate legislation or other administrative provisions, coupled with better extension and education facilities in the field of pesticide usage.
At present alternative methods of pest control are not available to the extent that they can be applied on a broad scale as full replacement of pesticides, but they offer possibilities in specific cases, either alone or in combination with selected or selective pesticides.
Research on alternative methods of pest control to be applied in combination with selected or selective pesticides (i.e. integrated pest control) should, therefore, be intensified, and in the meantime emphasis should be placed on a system of supervised control, which aims at a judicious use of pesticides coupled with assessment of economic threshold levels and forecasting systems.
Pesticide legislation or other effective control systems should be introduced and implemented in those countries where they have not yet been established; in other countries with existing legislation or administrative controls, these may need to be intensified in order to strike a better balance of benefits to agriculture against risks to humans, environment and food.
The extent to which regulations are introduced should, on the other hand, not go beyond reasonable and acceptable limits, in order to ensure that plant health and other pest control requirements as well as availability of adequate pesticides are not jeopardized. Regulations should be accompanied by enlightening and meaningful educational programmes on pesticide use and safety.
Legislation on pesticides deals mainly with two fundamental aspects, which are distinctly different though interrelated, i.e.:
(a) use pattern and handling regulations, pertaining to registration and approval on the basis of criteria for effecacy and for side-effects;
(b) residue regulations, pertaining to the establishment of maximum limits of pesticide residues in food and feed on the basis of "good agricultural practice".
Pesticide residues occur in agricultural commodities as a result of (a) intentional use of pesticides for protection of growing crops or stored products or of animals; (b) unintentional exposure to pesticides such as would occur in crops grown in soil treated previously or contaminated by foliar treatments of other crops grown earlier in the rotation; (c) unintentional accumulation in animals from the ingestion of feeds containing pesticide residues; and (d) contamination of crops or animals exposed to chemicals in the environment.
It has to be recognized that differences exist both between and within countries as to pest incidence, pest control conditions, and types of crops, which may be reflected in the different pesticide use patterns, pesticide demands and requirements regarding maximum residure limits.
The prime target of the Codex Alimentarius Commission is to reach agreement on international maximum limits for pesticide residues in food, in order to avoid trade barriers and to secure good agricultural practice under widely varying conditions.
As maximum residue limits, use pattern and good agricultural practice are interrelated, the Codex Committee on Pesticide Residues has also undertaken to formulate these guidelines for the use of pesticides.
Purpose of the Guidelines
These guidelines indicate principles for the use of pesticides in agriculture, and in the harvesting, marketing, transport and storage of foodstuffs. Taking into account the attainment of the desired degree of control of pests at an economic cost and with a minimum of danger to operators, agricultural workers, consumers, beneficial animals and the environment, the following represents a list of goals which should be aimed at in good practice in the use of pesticides for the above mentioned purposes. It should be understood that the information presented in the guidelines is not intended as a substitute for actual supervised trials under the growing conditions of the area involved.
(a) If pesticides reach humans or animals through different routes and thus give rise to additional body loads, the use patterns may have to be adjusted, and if necessary, priority should be given to those uses which are indispensable and for which no adequate alternatives are available.
(b) Maximum residue limits established for products for human consumption are not necessarily acceptable for the same product when this is destined for animal consumption and vice versa, and in such cases this should be indicated as far as possible.
(c) In view of the necessity of preserving a balance between cost, productivity, quality and freedom from residues, the concept of good agricultural practice in relation to pesticide residues embraces all interrelated and essential factors and functions, which ensure that the pests will be controlled effectively, leaving residues that are the smallest amounts practicable and that are toxicologically acceptable.
(d) Therefore, pest control treatments should only be made when necessary. The requirements for pest control should first be established, followed by the application of the preferred method of control.
Choice of Pesticide
(a) All pesticides which are used should be authorized (registered) by appropriate authorities in the country of use. They should only be marketed with labels indicating recommended or approved uses, times, methods and rates of application, and safety precautions for the uses. Such recommended methods of application, should be based on supervised trials and other experimental work, and should take into account such variations in climate, in crop husbandry, and in incidence of pests as may occur under practical conditions from time to time in the various places in which the pesticide may be used (see ALINORM 72/24A, pare 10, and WHO Technical Report series No. 592, page 40, Explanatory Note on Good Agricultural Practice).
(b) Bearing in mind the actual conditions under which the pesticide will be used, the pesticide should be adequately safe to humans and the environment, and at the same time provide adequate pest control.
(c) Where a choice of pesticides is possible, the cost and effectiveness of available pesticides should be weighed against the risks involved, and those which show a more favourable benefit-risk ratio for the particular purpose in question should be preferred.
(d) When pest control is required in the early growing stage of the crop, a pesticide may be needed which has an adequate and acceptable degree of persistence, in order to avoid repeated applications of non-persistent pesticides.
(e) Where plant quarantine and/or phytosanitary requirements make is necessary to apply pesticides close to or after harvest, those which have a short persistence should be preferred (see also 7(a) and 7(b)).
(f) The agricultural use of persistent and/or cumulative pesticides on crops for human consumption should be restricted as much as much as possible, and be limited to the control of pests, weeds and diseases for which at present no suitable alternative chemicals are available.
(g) As a general rule, persistent and/or cumulative pesticides should not be used on fodder crops and not be applied directly to animals for veterinary purposes.
(h) Where post-harvest treatments are required, pesticides which leave residues that are the smallest amounts practicable and that are toxicologically acceptable, do not interact with the food commodity, and/or are readily removed during storage, preparation or cooking, should be preferred.
(i) With respect to post-harvest treatment of stored products (e.g. cereal grains) it is recommended no to use persistent and cumulative pesticides as direct admixture.
(j) The application of adequately durable pesticides to the exterior of packing material for stored products is acceptable, but the use of highly persistent and cumulative pesticides should be avoided as much as possible.
Choice of Formulation
(a) Formulations which combine maximum efficiency of the pesticide with minimum risk should be preferred.
(b) Supplementary adjuvants should be used only if their effects, including toxicological effects, are known and where their use produces a significant improvement in performance.
(c) In general, the use of combined pesticide/ fertilizer formulations should be avoided, However, such practices are recommended by local authorities when they are considered beneficial.
(a) The quantity of pesticide applied should not be greater than the minimum required to achieve the desired degree of control.
(b) The number of treatments should be determined by the desired degree of control and by the severity of pest conditions.
(a) The method of application should be selected to ensure optimum pest control with the minimum contamination of the crop and the environment.
(b) Indirect treatment (such as application to the soil, seed dressing, fumigation of empty silo cells, treatment of alternate hosts)'can, in some cases, be used to supplement or replace direct application to food crops.
(c) Application equipment should at all times be maintained and used according to the makers' instructions.
Timing of Treatment
(a) Treatment should preferably be carried out when the pests are at the most vulnerable stage of development, and when climatic conditions and cultural practices will ensure that the optimum effect can be attained from the treatment. In some instances, however, action may be necessary immediately following detection of the pest species.
(b) The interval between last application and harvest (slaughter in the case of veterinary use) should be as long as possible in order to permit the greatest reduction in pesticide residues, bearing in mind the pest incidence, the degree of control required for a maximum utilization of the commodity, and the vulnerability of the treated crop immediately preharvest. To this end official pre-harvest intervals should be established and adhered to.
(a) Crop rotation should be adjusted in such a manner that unintentional residues in the edible parts of the crop, as a result of previous treatments, will be minimal, particularly if the crop may be used as animal feed, and accumulation in the animal body may lead to undue residues in food products of animal origin.
(b) Seed-grain, treated with pesticides at dosages to provide long-term protection in the soil, must, under no circumstanes, be mixed with commodities destined for human or animal consumption. Sufficient safeguards ought to be provided which would minimize the accident risk of such practices.
(c) Where grain intended for consumption must be protected in storage, only compounds with low chronic toxicity and/or shourt persistence should be used.
(d) In storage practice, the selection of the pesticide for treatment of empty warehouses or ship holds and the subsequent storage arrangements should be such that there is a minimum risk of contaminating feed or food products.
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