Benz[a]anthracene-induced alterations in the metabolic activation of benzo[a]pyrene by hamster embryo cell cultures.

Co-administration of benz[a]anthracene (BA) with benzo[a]pyrene (B[a]P) to hamster embryo cell cultures for 24 h resulted in a decrease in the metabolism of benzo[a]pyrene by 40%, a decrease in the level of binding of B[a]P to DNA by 70% and a 10-fold reduction in mutation induction in a hamster embryo cell-mediated V79 cell mutation assay. This data indicates that the biological effects of co-administration of BA with B[a]P result from inhibition of the metabolic activation of B[a]P rather than induction of enzymes that detoxify the B[a]P.