Safe Use of Pesticides in Food Production; a Report [by] W.J. Darby, Chairman ... [Et Al.] (1956)

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of chemicals so that they may prescribe specific treatments to fit specific condi- tions. The time is past when agriculture can produce efficiently with only a few pest control materials such as sulfur, copper salts, nicotine, and arsenicals. Today about 100 active materials are being used in the preparation of over 40,000 trade brand pesticides currently regis- tered with the Pesticide Registration Section of the Department of Agricul- ture. Even this relatively large number of active materials is not entirely ade- quate because of the multitude of pests to be controlled, the ability of certain species of pests to acquire resistance to particular chemicals, the necessity of substitution when infestation occurs im- mediately before harvest, and the ex- tremely variable conditions of weather and climate under which the materials must be used. The public welfare demands that two things be done. Every effort must be made to encourage the development of better pesticides, and every possible pre- caution must be taken to see that they are prepared and used in such a fashion that the public will not be exposed to unnecessary hazard. The two require- ments are not at all incompatible, and gratifying progress is being made in both directions. THE HAZARD FROM PESTICIDES Most pesticides have some toxic prop- erties, but this does not necessarily mean that their use will create a hazard to public health. Toxicity and hazard are not synonymous terms. Toxicity is the capacity of a substance to produce injury; hazard is the probability that injury will result from the use of the substance in the quantity and manner proposed. For example, the most toxic material will not present a food hazard if it evaporates or becomes nontoxic by decomposition before the crop is used for food. In any attempt to evaluate hazard, one must distinguish between use or opera- tional hazards involved in applying pesti- cides and the hazards involved in food contamination. In general, operational hazards are related to the acute and sub- acute toxicity of the pesticide and may be estimated from the relative toxicity of the material and the degree of ex- posure to it. The user must be fully in- formed through proper labeling and ade- quate instructions regarding the hazards involved. He should then be at liberty to make a free choice from the materials available and assume full responsibility for his actions. Every effort should be made to reduce operational hazards to a minimum. That such efforts are effective may be re- flected in the fact that farm accidents involving pesticidal chemicals are in- significant in number when compared with farm accidents from use of mechan- ical tools. Food hazard is, in general, closely related to chronic toxicity of the pesti- cide. Chronic toxicity is estimated from biological changes in animals exposed to the intake of small doses of a material over a protracted period. If the mini- mum dose of a pesticide causing chronic effects is known, hazard can be esti- mated from the amount of residue re- maining on or in food reaching the con- sumer. The inherent toxicity of a pesticide to warm-blooded animals may have little or no direct bearing on the final food hazard. Many of the more toxic mate- rials are applied at times when the edi- ble portion of the crop is not exposed. As a rule, such chemicals are applied in proportionately smaller amounts than are less toxic materials, and frequently