An enhanced thirteen-week bioassay as an alternative for screening for carcinogenesis factors.

Utilizing basic concepts of chemical carcinogenesis and the human relevance framework based on mode of action analysis of animal carcinogens, an alternative is proposed for the two-year bioassay for screening chemicals for potential carcinogenic risk in humans. This model includes short-term screening of chemicals for DNA reactivity, immunosuppressive and, estrogenic activity, and potential increased cell proliferation. Follow-up studies can provide detailed information with regard to dose response and mode of action, with a detailed evaluation of potential relevance to humans. It is no longer appropriate to continue performing two year rodent bioassays.