Nitro Compounds in Environmental Mixtures and Foods

Nitropyrenes (NPs) are the most potent mutagens that have been detected in environmental pollutants such as airborne particulates (Tokiwa et al., 1981b), car exhaust emissions (Lee et al., 1980; Gibson et al., 1981; Pederson and Siak, 1981; Schuetzle et al., 1981), photocopies (Lofroth et al., 1980; Rosenkranz et al., 1980), wastewater from gasoline stations (Ohnishi et al., 1983; Manabe et al., 1984), and used crankcase oil (Manabe et al., 1984). They are direct-acting mutagens in the Ames Salmonella mutation test; 1-NP, 1,3-diNP, 1,6-diNP, and 1,8-diNP produce 417; 65,500; 82,000; and 100,000 His+ revertants/plate/nmol, respectively, from strain TA98 in the absence of rat liver S9 mix (unpublished data). To induce mutagenicity the NPs are converted to the activated forms by nitroreductases in theSalmonella tester strain (TA98). Since strains TA98NR and TA98/1,8-DNP6 are defective in the specific activating enzymes, they show low mutagenicity by 1-NP and diNPs (Rosenkranz et al., 1981).