Transgenic mouse mutation assay systems can play an important role in regulatory mutagenicity testing in vivo for the detection of site-of-contact mutagens

Transgenic mouse mutation assays, such as Muta(TM)Mouse (lacZ, CD2F1) and B ig Blue(R) (lacI, B6C3F1), afford the opportunity to evaluate the mutagenic potential of chemicals in any target organ in vivo. This paper discusses p ublished data collected from the analysis of the skin, stomach and lung DNA after topical, oral and inhalation exposure, respectively. These data indi cate that both Muta(TM)Mouse and Big Blue(R) should play an important part in the evaluation of genotoxicity in vivo, particularly where the endpoint or target tissue available in the more conventional tests is inappropriate. It is concluded that there is a distinct role for this type of assay in ge netic toxicology testing. For substances applied to the skin or dosed orall y or by inhalation and which are unlikely to reach either the bone marrow o r the liver, then data derived from these assays may be more relevant to an assessment of possible risk to man than the currently used unscheduled DNA synthesis in liver and cytogenetics assays in bone marrow or peripheral bl ood.