GENERATION OF MUTAGENIC TRANSFORMATION PRODUCTS DURING THE IRRADIATION OF SIMULATED URBAN ATMOSPHERES

Mixtures of air pollutants simulating urban atmospheres were irradiated in a smog chamber, and the resultant products were monitored for the production of mutagenic and other hazardous compounds. The production of biologically active compounds was detected through use of the Ames mutagenicity assay with Salmonella typhimurium, strain TA100. Irradiations of the pollutant mixture were conducted at HC/NO(x) ratios of 20 and 11. Overall, the mutagenicity of the products and the formation of oxygenated primary and secondary reaction products were greater for the simulations with the higher initial HC/NO(x) value. The origin of the mutagenicity from the reactant mixture was examined by conducting experiments with individual paraffinic, olefinic, and aromatic hydrocarbons. The chemicals examined during this aspect of the study were the paraffin n-butane, the olefin propylene, and the aromatic toluene. For the conditions studied, the activity of the toluene products was generally greater than that of propylene or n-butane, and the propylene products showed greater activity than did the n-butane products. The production of n-butane products was generally limited by its low rate of reaction with hydroxyl radicals. Photo-oxidation products from secondary reactions were most important in the toluene and propylene systems.