METABOLISM AND BACTERIAL MUTAGENICITY OF BINARY-MIXTURES OF BENZO(A)PYRENE AND POLYCHLORINATED AROMATIC-HYDROCARBONS

The results of both the Salmonella/microsome mutagenicity assay and high‐performance liquid chromatography (HPLC) analysis were used to evaluate the interactions of binary mixtures of benzo(a)pyrene (BAP) and several different polychlorinated aromatic hydrocarbons. Binary mixtures of either 2‐nitro‐3,7,8‐trichlorodibenzo‐p‐dioxin (2NTCDD) or pentachlorophenol (PCP) with BAP produced synergism, whereas strictly additive effects were observed with mixtures of acta‐ or hepta‐chlorodibenzo‐p‐dioxin and BAP. At a dose of 50 μg per plate, BAP induced 120 total revertants, whereas the binary mixture of BAP and PCP induced 303 total revertants. The binary mixture of BAP at 1 μg per plate and 2NTCDD at 0.5 μg per plate induced 261 net revertants, whereas BAP alone induced 42 net revertants. HPLC analysis of the mixtures indicated that preincubation of BAP with 2NTCDD increased the quantity of benzo(a)pyrene‐7,8‐dihydrodiol, and 9,10‐dihydrodiol metabolites detected. The data suggest that nonmutagenic components of a complex mixture may alter the metabolism of promixate mutagens. Thus, in the present study, 2NTCDD appears to have inhibited the detoxication of BAP metabolites. Copyright © 1990 Wiley‐Liss, Inc., A Wiley Company