| Summary: | This study presents the first investigation into the occurrence of N-nitrosodiphenylamine (NDPhA), a thermally unstable nitrosamine, in drinking water from Canada and the United States. NDPhA, in addition to 8 other nitrosamines, were determined in water samples collected from 38 drinking water distribution systems using high performance liquid chromatography-tandem mass spectrometry (LC/MS/MS). Of the 9 nitrosamines analyzed, NDPhA, NMor and NDMA were detected. Our results show that nitrosamine concentrations change in the distribution system, demonstrating that measurements done solely at the water treatment plant may misestimate the nitrosamine concentrations consumers are exposed to and that NDPhA exposure should be explored. These results are useful for directing future exposure assessments and chloramination treatment.
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