Abstract
Mutagenicity of the product induced by phtochemical reaction of road-coating asphalt with nitrogen dioxide (NO2) was investigated using S. typhimurium strains TA98, TA100 and TA98NR, a nitroreductasedeficient strain, and TA98/1, 8-DNP6, a resistant strain to mutagenicity of 1, 8-dinitropyrene.
An asphalt material dissolved in benzene was deposited on filter papers and was dried to remove benzene. This material was then exposed to NO2 (10 ppm) in air stream being irradiated with high pressure mercury lamp for from 0.5 to 4 hr.
Only phtochemical reaction product without exposure to NO2 was not mutagenic for strains TA98 and TA100 with or without S-9 mix, but the product obtained by the reaction with NO2 showed mutagenicity for strains TA98 without S-9 mix (705 revertants/100μg). The mutagenicity of the reaction-product resulted in the marked reduction for strains TA98NR and TA98/1, 8-DNP6. These results suggest that nitroarenes are responsible for most of the mutagenicity. Total mutagenic activity of photochemical reaction-product did not show constant mutagenicity in spite of the amount of asphalt deposited on filters. Therefore, it was suggested that the mutagens were produced by light irradiation on the surface of asphalt deposited on filter papers.
