The lifetime feeding study in mice and rats--an examination of its validity as a bioassay for human carcinogens.

Currently used designs for carcinogenic bioassay (lifetime feeding studies in mice or rats using maximum tolerated doses of the test compound) are examined to see if they meet the requirements of a bioassay, using the results of 170 compounds reported on as of June, 1980, by the National Cancer Institute. It is concluded that the lifetime feeding study has never been subjected to proper validation as an assay for human carcinogens. When an attempt is made to validate it on the basis of these reported studies and those in the literature, it appears to lack acceptable specificity and sensitivity. It is suggested that a drastically different design is needed and that such redesigning of the assay will require proper validation.