Environmental mutagens in urban air particulates.

A bioassay capable of detecting carcinogenic substances that are associated with the elevated incidence of cancer in the urban environment would be important for epidemiologic and environmental analyses. The feasibility of using the Salmonella mutagenesis system developed by Ames for this purpose has been tested by analyzing Chicago air particulate samples. Active material, as evidenced by enhanced rates of mutation, both in the presence of microsomes and in their absence, is readily extractable from samples of air particulates. Dose-response curves have been obtained from such extracts of 15 successive samples, taken at intervals during 1975 from a sampling site in South Chicago. A method for analyzing such data in order to evaluate the relative mutagenic activity of different samples is described. The presence of a number of mutagenic constituents has been demonstrated by means of thin-layer chromatography of particularly active samples, in which the active material is located by mutagenic analysis of successive chromatographic zones. Mass spectrometer analysis of material isolated from an original sample in this way indicates that benzo[a]pyrene and benzo[e]pyrene, which are known to be mutagenic and carcinogenic, are present. It is concluded that within certain constraints, which are described, the methodology can serve the purpose of an environmental bioassay for organic carcinogens.