Abstract
The universality of the genetic system in living organisms and the high experimental correlation between mutagenicity and carcinogenicity provide the rational basis for the use of mutagenicity in screening of possible carcinogens. The present genetic methodologies using microorganisms, cell cultures, Drosophila, and rodents are evaluated. No mutagenicity test can cover all aspects of tumor formation in the whole animal or human body, because each species and tissue has its own capacity for repair as well as balance of activation and deactivation mechanisms. The strategy of testing must vary, depending on the nature and use of the chemicals.