Fluoranthene and pyrene enhance benzo[a]pyrene--DNA adduct formation in vivo in mouse skin.

Fluoranthene and pyrene are potent cocarcinogens when applied together with benzo[a]pyrene (BaP) on mouse skin. In this study the effect of fluoranthene, pyrene and phenanthrene on the formation of BaP--DNA adducts in mouse skin was investigated. Co-application of either fluoranthene or pyrene with [3H]BaP resulted in an average increase in the level of [3H]BaP--DNA adducts of 56% to 66%, respectively, as compared to [3H]BaP alone. Only minor differences were observed in the ratio of (+/-)anti- to (+/-)synbenzo[a]pyrene diol epoxide--DNA adducts between experimental groups. An average 17% decrease in the formation of [3H]BaP--DNA adducts was observed upon co-application of [3H]BaP on mouse skin with phenanthrene. These data suggest a correlation between the observed increase in tumorigenicity of BaP in the presence of either fluoranthene or pyrene and an increase in the formation of (+/-)anti-benzo[a]pyrene diol epoxide--DNA adducts.