The genotoxicity of unsubstituted and nitrated polycyclic aromatic hydrocarbons.

To determine the DNA damaging properties of unsubstituted and substituted polycyclic hydrocarbons, 61 aromatic and heterocyclic compounds were examined for the induction of the SOS system in E. coli PQ37. PAH such as benzo[ghi]fluoranthene, benzo[j]fluoranthene, benzo[c]phenanthrene, benzo[a]pyrene, chrysene, dibenzo[a,1]pyrene, fluoranthene and triphenylene showed relatively high genotoxicity. With respect to the nitroarenes, the highest genotoxic potencies were exhibited by the dinitropyrenes. The SOS-inducing potency of nitroarenes increased from the bicyclic to the tetracyclic ring system. Additionally, it was seen that any increase in the extent of nitration is paralleled by an increase of genotoxicity. Whereas PAH required metabolic activation by hepatic cytochrome P-450 enzymes, nPAH were direct-acting genotoxicants.