Cyclopenta[cd]fluoranthene and its precursors in combustion exhausts: A survey of their bacterial mutagenic activity

Cyclopenta[cd]fluoranthene ( 1 ) and 3‐ethynylfluoranthene ( 2 ) have both recently been identified in combustion exhausts. In this study, their mutagenic activities were compared to that of fluoranthene ( 3 ), one of the most abundant polycyclic aromatic hydrocarbons (PAHs) in combustion exhausts, in the Salmonella/microsome reversion assay (Ames assay) using S. typhimurium strain TA98. The mutagenicity of 1 was modest in comparison to other active cyclopenta PAHs. Unexpectedly, 2 was mutagenic both with and without exogenous metabolic activation (rat liver S9). Furthermore, cyclopenta[cd]fluoranthene‐3,4‐epoxide ( 6 ) was synthesized in order to evaluate its role as the ultimate mutagenic active form of 1 . The epoxide 6 was a direct‐acting mutagen. In addition, a pyrolysate containing a mixture of 1 (85%), 2 (2%), and 3 (13%) obtained by flash vacuum thermolysis of 3‐(1‐chloroethenyl)fluoranthene ( 2a ) at 1,050°C was also mutagenic, but a significant mutagenic response was detected only in the presence of S9 activation. The results of this study indicate that 1 and 2 can contribute to the mutagenic activity of combustion exhausts. Environ. Mol. Mutagen. 44:304–312, 2004. © 2004 Wiley‐Liss, Inc.