Quantitative analyses of radiation- and chemical-induced lethality and mutagenesis in Chinese hamster ovary cells

The Chinese hamster ovary cell/hypoxanthine-guanine phosphoribosyl transferase (CHO/HGPRT) mutational assay selects for mutant clones, of which greater than 98% are deficient in HGPRT enzyme activity. This system sensitively determines the mutagenicity of a variety of chemical and physical agents. With all chemical mutagens studied, mutation induction increases linearly with increasing mutagen concentration, without an apparent threshold effect. Direct-acting alkylating agents were used to study the interrelationships among chemical structure, cellular lethality, and mutagenic activity. Physical agents such as uv and x irradiation and various light sources were also studied. Among a total of 42 agents with documented carcinogenic or noncarcinogenic activity, the correlation with mutagenic activity in the CHO/HGPRT system was 95.2%