The Testing Scheme

The selection of toxicological tests is crucial to any experimental program. Similarly, decisions regarding: the amount of chemical to be tested; the route of exposure; the test animal species; the composition of the test population (homogeneous or heterogeneous); the effects to be observed; and the duration of the study affect the usefulness and reliability of the resulting data. Although based on scientific judgment, all such decisions introduce elements of subjectivity into the testing scheme. The outcome of the test may be shaped by the specific nature of the test itself. For example, the decision to conduct an inhalation study might preclude discovering toxic effects via a different route of exposure. For this reason, a route of exposure is selected to approximate real-life conditions.

Demonstration of carcinogenicity requires strict observance of analytical protocols. NCI (IRLG 1979) presents criteria for evaluating experimental designs (see Table 11.8.1). Laboratory data not developed in compliance with these protocols are questionable.

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