Genotoxic activity of 1-nitropyrene in water from the Yodo River, Japan

The identification of mutagenic 1-nitropyrene, one of the direct-acting nitroarenes, in a source of municipal drinking water is described. A diethyl ether extract recovered from river water by the XAD-2 resin column method was separated into neutral, acid and basic fractions. The neutral fraction accounted for 52 and 36%, respectively, of the genotoxicity of the extract in the absence and the presence of the metabolic activation system, for strain NM2009, which is sensitive to nitroarenes and/or aminoarenes. When separated by silica gel column chromatography, the benzene fraction of the neutral fraction, showed the highest genotoxic activity. The genotoxicity of the benzene fraction accounted for 80 and 60%, respectively, of the neutral fraction, in the absence and the presence of S9 mix. These results show that mutagenic nitroarenes might be contained in the benzene fraction of the neutral one. The benzene fraction was further subjected to HPLC and fractionated. A 1-nitropyrene-corresponding fraction was collected and subjected to capillary gas chromatography-mass spectrometry (GC-MS). The mass spectrum showed molecular and fragment ion peaks of 1-nitropyrene: 247, 217, 201, 189. Moreover, the concentration of 1-nitropyrene in municipal river water was 1 ng/l, accounting for only 1% of the total genotoxicity.