Formation of N -Nitrosamines in Drinking Water Sources: Case Studies From Western Australia

The occurrence and formation of N-nitrosamines in water supplies is of concern to the water industry, as N-nitrosamines have been reported to be carcinogenic, mutagenic, and/or teratogenic. The US Environmental Protection Agency’s (USEPA’s) Integrated Risk Information System indicates that N-nitrosodimethylamine (NDMA) is a probable human carcinogen (USEPA 1997). Other N-nitrosamines typically measured are shown in Table 1. Although N-nitrosamines are present at very low concentrations, they are more toxic than trihalomethanes and haloacetic acids and represent a greater potential public health risk. The N-nitrosamine that is most frequently detected in drinking water is NDMA, which is often, but not always, associated with anthropogenic impact on the source water and with chloraminated drinking waters (Uzun et al. 2015, Krasner et al. 2013, Charrois et al. 2007, Mitch et al. 2003a). Eight other N-nitrosamines have also been reported in drinking waters, but they are detected less frequently and at lower concentrations (typically <10 ng/L) than NDMA (Bei et al. 2016; Liew et al. 2016; Wang et al. 2016; Brisson et al. 2013; Templeton & Chen 2010; Charrois et al. 2007, 2004). N-nitrosamines that have previously been detected in chloraminated systems include N-nitrosopyrrolidine (NPYR), N-nitrosomorpholine (NMOR) (Boyd et al. 2011, Charrois et al. 2004), and N-nitrosoethylmethylamine, or NEMA (Brisson et al. 2013). N-nitrosamines that have been detected in chlorinated waters include N-nitrosodiethylamine (NDEA), NPYR, and NMOR (Planas et al. 2008), N-nitrosodibutylamine, or NDBA (Templeton & Chen 2010), and N-nitrosopiperidine, or NPIP (Brisson et al. 2013). Recent studies from China have shown more frequent occurrence of N-nitrosamines at higher concentrations (Bei et al. 2016, Wang et al. 2016). This higher formation has been linked to the presence of secondary amines (e.g., dimethylamine and diethylamine) in the source water (Ma et al. 2012, Wang et al. 2011), failure to achieve breakpoint chlorination at many Chinese drinking water treatment plants (Bei et al. 2016), and the potential effect of wastewater and industrial discharge on drinking water quality (Bei et al. 2016, Wang et al. 2016). Chemicals identified as precursors for NDMA include natural amines (secondary and tertiary amines) in source waters, or amine-based coagulants used in the watertreatment process (Hanigan et al. 2015, Shah & Mitch 2012, Mitch et al. 2003a). Rubber products have been reported as a source of both N-nitrosamines and Peer Reviewed