Transformation of rat and mouse embryo cells by a new class of carcinogenic compounds isolated from particles in city air.

Abstract

AbstractThe customary benzene extraction of airborne particulate matter collected in Los Angeles has previously been shown to yield carcinogenic material. The residue from the benzene extraction contains substances soluble in methanol, some of which are organic. This methanol extract and a number of its component fractions have been tested in rodent cell culture systems developed as assay methods for screening carcinogens. In one system a high‐passage Fischer rat embryo cell line was used. In the other a low‐passage cell line derived from NIH Swiss albino mouse embryos and infected with AKR leukemia virus was used. In both systems the methanol extract showed cell transformation activity approaching that of 3‐methylcholanthrene. In the mouse cell system the activities of several fractions were also examined. The major inorganic component, ammonium nitrate, showed no activity. Neither the neutrals alone nor the recombined non‐neutral fractions separately showed any activity, although they were active together. The basic materials separated by ion exchange were also active. The methanol extract combined with the conventional benzene extract showed much lower activity than either extract alone.