The induction of somatic mutations in mouse embryos by benzo(a)pyrene

With the object of establishing a test for specific locus mutations in the somatic cells of mice, the effect of benzo(a)pyrene on the developing pigment cells of mouse embryos was investigated. Embryos were heterozygous for genes affecting coat-colour so that mutations could be scored as spots on the adult mouse. If the pregnant female was treated, with 2 mg/day orally, before day 7 or after day 10 of pregnancy no mutations were seen in the offspring. Treatment at any time from day 7 to day 10 was effective in producing mutations with no day giving a peak response. The effect of treatment on consecutive days appears to be additive. It is suggested that further chemicals be investigated lest differing rates of uptake and metabolism should alter the period in which treatment should be given in order to detect a mutagenic effect.