Mutagenicity of photochemical reaction products of polycyclic aromatic hydrocarbons with nitrite.

Six kinds of polycyclic aromatic hydrocarbons (PAHs) were subjected to ultraviolet light irradiation with nitrite for 1, 4, 8 and 24 h, and the irradiated samples were tested for mutagenicity towards Salmonella typhimurium TA 98, TA 100 and TA 1538. Irradiated samples of pyrene, fluoranthene and benzo[a]pyrene showed marked mutagen responses towards TA 98 and TA 1538, especially in the absence of S9 mix. The direct-acting mutagenic activity of these samples, showing high activities at 1-8 h, decreased greatly with the development of irradiation. Further, these direct-acting mutagens were mostly present in the neutral fraction. On the other hand, the mutagenicity of the irradiated sample of 5,6-benzoquinoline was high both with and without S9 mix, and was mostly present in the basic fraction because of its authentic characteristic. There was no correlation between the yield of 1-nitropyrene and the mutagenic activity of the photochemical reaction product of pyrene with nitrite. Further studies by TLC separation suggested that a considerable number of direct-acting mutagens formed in this experiment were more polar than nitrated PAH such as 1-nitropyrene.