For a pesticide to be registered, manufacturers must submit to EPA the data needed to support the product's registration, including substantiation of its usefulness and disclosure of its chemical and toxic properties, its likely distribution in the environment, and its possible effects on wildlife and plants.

Pesticides that are to be registered for use on food crops must be granted a tolerance by EPA. These tolerances constitute the principal mechanism by which EPA limits levels of pesticides residues in foods. A tolerance concentration is defined under FFDCA as the maximum quantity of a pesticide residue allowable on a raw agricultural commodity (RAC) (FFDCA, Section 408) and in processed food when the pesticide has concentrated during processing (FFDCA, Section 409). A tolerance must be defined for any pesticide used on food crops. Tolerance concentrations on RACs are based on the result of field trials conducted by pesticide manufacturers and are designed to reflect the highest residue concentrations likely under normal agricultural practice. Thus, tolerances are based on good agricultural practice rather than on considerations of human health.

The determination of what might be a safe level of residue exposure is made by considering the results of toxicological studies of the pesticide's effects on animals and, when data are available, on humans. Both acute and chronic effects, including cancer, are considered, although currently, acute effects are treated separately. These data are used to establish human exposure guidelines (i.e., reference dose, RfD) against which one can compare the expected exposure. Exposure is a function of the amount and kind of foods consumed and the amount and identity of residues in the foods (i.e., Theoretical Maximum Residue Contributions, TMRCs). If the TMRCs exceed the RfD, then anticipated residues are calculated and compared with the proposed tolerance. The percent of crop acreage treated is also considered. If the anticipated residues exceed the RfD, then the proposed tolerance is rejected, and the manufacturer may recommend a new level.

Tolerances are the single most important tool by which the U.S. Government regulates pesticide residues in food. More than 8,500 food tolerances for all pesticides are currently listed in the Code of Federal Regulations (CFR). Approximately 8,350 of these tolerances are for residues on raw commodities (promulgated under section 408) and about 150 are for residues known to concentrate in processed foods (promulgated under Section 409). Table 1-1 shows the number of tolerances established for insecticides, herbicides, and fungicides in the mid-1980s for purposes of comparison.

APPROACH TO THE STUDY

Infants and children are unique. They are undergoing growth and development. Their metabolic rates are rapid. Their diets and their patterns



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