An evaluation of the roles of mammalian cell mutation assays in the testing of chemical genotoxicity.

The present status of the applicability of mammalian cell gene mutation assays in the safety evaluation of industrial chemicals is evaluated from the industrial and regulatory point of view, with emphasis being placed on the CHO/HGPRT and mouse lymphoma tk +/- assays. The CHO/HGPRT assay was concluded to be a highly specific assay, but it might be less sensitive to mutagens that mainly induced large deletions. The mouse lymphoma assay was concluded to be sensitive, but it might have a lower specificity due to experimental artifacts such as pH and osmolality changes. Mammalian gene mutation assays, when conducted within their limitations, are concluded to be valuable in safety evaluation, providing results complementary to the Ames test and cytogenetic assays.