Abstract
Biphenyl (BP) was irradiated under a xenon lamp in the presence of various concentrations of NOX. Some nitrobiphenyl compounds (2-nitrobiphenyl, 4-nitrobiphenyl, 2, 2'-dinitrobiphenyl, 2, 4'-dinitrobiphenyl and 4, 4'-dinitrobiphenyl) were detected among the reaction products by gas chromatography. The organic compounds were tested for mutagenicity towards Salmonella typhimurium TA 98 by means of the plate-incorporation test, and 4, 4'-dinitrobiphenyl was the most potent mutagen among the products identified in the present study. However, the mutagenicity of the photochemical reaction mixture of biphenyl (1 mmol) with NOX (6 mmol) was about eight times stronger than that of an artificial mixture of intact biphenyl and the identified nitrobiphenyls in the absence of the S-9 microsomal activation system. In summary, unidentified components of the photochemical reaction mixture of biphenyl with NOX are the major direct mutagens ; the amount of these components increased with increasing amount of NOX, and reached 54.8% of the total reaction mixture by weight (for 1 mmol BP with 6 mmol NOX).
