Mouse skin tumor-initiating activity of benz[e]aceanthrylene and benz[l]aceanthrylene in SENCAR mice.

Benz[e] aceanthrylene (B[e]A) and benz[l] aceanthrylene (B[l]A), cyclopenta-fused derivatives of benz[a]anthracene, have been reported to be active bacterial cell and mammalian cell gene mutagens. In this study they were evaluated as skin tumor initiators in both male and female SENCAR mice. Both polycyclic aromatic hydrocarbons (PAHs) induced papilloma formation in the range of 50-1000 nmol/mouse. B[l]A was the most active, being approximately 4 times as active as benzo[a]pyrene (B[a]P) while B[e]A had activity approximately equivalent to B[a]P. These results are in contrast to those reported for the air pollutant, cyclopenta[cd]pyrene, another cyclopenta-fused PAH, which is a weak mouse skin tumor initiator. We postulate that these cyclopenta-PAHs are formed by pyrosynthetic routes similar to other environmental cyclopenta-PAHs and that they may be of importance as contributors to air pollution carcinogenesis.