There now exists a very large body of information that directly links the exposure to certain environmental factors with the ultimate development of specific types of human cancer. For this reason, a number of tests possessing varying degrees of biological complexity have been devised with the intent to first identify, and then ultimately reduce the risk of exposure to tumor causing agents. The presently employed chronic whole animal tests generally accepted as measures of human carcinogenicity have certain limitations in that they are lengthy to perform, very expensive, and require complicated pathological examinations of the various tissues. Consequently, there exists a need for short-term whole animal bioassays that can serve to complement such lengthy chronic studies; we are proposing that one such a test can be developed through utilizing procedures that have been designed for evaluating T-cell immunological responses.