BACTERIAL AND HUMAN CELL MUTAGENICITY STUDY OF SOME C18H10 CYCLOPENTA-FUSED POLYCYCLIC AROMATIC-HYDROCARBONS ASSOCIATED WITH FOSSIL-FUELS COMBUSTION

A number of isomeric C18H10 polycyclic aromatic hydrocarbons (PAHs), t hought to be primarily cyclopenta-fused PAHs, are produced during the combustion and pyrolysis of fossil fuels. To determine the importance of their contributions to the total mutagenic activity of combustion a nd pyrolysis samples in which they are found, we characterized referen ce quantities of four C18H10 CP-PAHs: benzo[ghi]fluoranthene (BF), cyc lopenta[cd]pyrene (CPP), cyclopent[hi]acephenanthrylene (CPAP), and cy clopent[hi]aceanthrylene (CPAA). Synthesis of CPAA and CPAP is describ ed. The availability of reference samples of these isomers also proved to be an essential aid in the identification of the C18H10 species of ten found in combustion and pyrolysis samples. Chemical analysis of se lected combustion and pyrolysis samples showed that CPP was generally the most abundant C18H10 isomer, followed by CPAP and BF. CPAA was det ected only in pyrolysis products from pure PAHs. We tested the four C1 8H10 PAHs for mutagenicity in a forward mutation assay using S. typhim urium. CPP, BF, and CPAA were roughly twice as mutagenic as benzo[a]py rene (BaP), whereas CPAP was only slightly active. These PAHs were als o tested for mutagenic activity in human cells. In this assay, CPP and CPAA were strongly mutagenic but less active than BaP, whereas CPAP a nd BF were inactive at the dose levels tested. Also, the bacterial and human cell mutagenicity of CPAA and CPAP were compared with the mutag enicity of their monocyclopenta-fused analogs, aceanthrylene and aceph enanthrylene. Although the mutagenicities of CPAP and acephenanthrylen e are similar, the mutagenic activity of CPAA is an order of magnitude greater than that of aceanthrylene.