• carcinogenicity

• developmental toxicity

• mutagenicity tests

• general metabolism study

More than 30% of the tests for pesticides submitted to EPA in the past have been rejected. Those rejected must be resubmitted until they are in conformance with EPA criteria before registrations can be granted. The criteria for rejection are summarized in Table 4-3. Some of them fall in the category of regulatory policy; others involve scientific concerns. The most commonly cited reason for noncompliance is lack of characterization of the test material. To improve the quality of testing and incorporate new scientific methods in its testing requirements, EPA is currently revising the 40 CFR Part 158 data requirements for food and nonfood use pesticides. The proposed revisions to these requirements can be found in Table 4-4.

ACUTE TOXICITY STUDIES

General Description

Acute toxicity studies provide information on the potential for health hazards that may arise as result of short-term exposure. Determination of acute oral, dermal, and inhalation toxicity is usually the initial step in evaluating the toxic characteristics of a pesticide. In each of these tests the animal is exposed to the test material only once on 1 day. Together with information derived from primary eye and primary dermal irritation studies (also 1 dose on 1 day), which assess possible hazards resulting from pesticide contact with eyes and skin, these data provide a basis for precautionary labeling and may influence the classification of a pesticide for restricted use. Acute toxicity data also provide information used to determine the need for child-resistant packaging, for protective clothing requirements for applicator, and for calculation of farm worker reentry intervals. A minimum number of animals, usually adults, are used in these studies and only the end points of concern are monitored, i.e., mortality, observable skin or eye effects, dermal sensitization, and observable neurotoxic behavioral changes. One exception is the inclusion of microscopic examination of neural tissues in the newly required acute neurotoxicity study.

EPA's Proposed Changes

Guideline number 81-1 (EPA, 1984), acute oral study in the rat, would be revised to include special visual system testing, which would be required for all organophosphate pesticide and other pesticides known to affect the visual system.



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