Chemicals showing no evidence of carcinogenicity in long-term, two-species rodent studies: the need for short-term test data.

Studies to determine the performance of short-term tests (STT) in predicting chemical carcinogenicity are frequently characterized by a poor representation of noncarcinogens among the test chemicals. As a result, the performance of several STT is well characterized with carcinogenic chemicals, but the ability of the tests to discriminate between carcinogens and noncarcinogens is largely unknown because of the shortage of test results for noncarcinogens. A list of 70 chemicals that have been tested by the National Cancer Institute or the National Toxicology Program in long-term rodent carcinogenicity studies and that have yielded no evidence of cancer induction in male and female rats and mice is presented. The list helps document the shortage of STT results of noncarcinogens and provides a potential source of chemicals for consideration in future studies designed to assess the ability of STT to predict chemical carcinogenicity.