NDMA Formation in Water and Wastewater

Abstract

N‐nitrosodimethylamine (NDMA) is a carcinogen known to be present in various foods and industrial products. The US Environmental Protection Agency has established a 10–6 cancer risk level for NDMA of 0.7 ng/L. NDMA has been found in the effluents of various water and wastewater plants, but its formation mechanism is not yet understood. This study evaluated NDMA formation during various water and wastewater treatment processes including chlorination and chloramination, ozonation, and ion exchange. On the basis of the limited results obtained in this study, NDMA appears to be a by‐product of the chloramination of water and wastewater, with the level of NDMA formed directly related to the chloramine dose. In the waters tested, NDMA did not form on contact with free chlorine or ozone. Contact of one water with typical levels of amine‐based polymer did not form any measurable NDMA levels (<2 ng/L). Batch testing was conducted with four strong‐base anion exchange resins contacted with untreated groundwater and with buffered deionized water. Results showed that some resins might leach or form NDMA and the level of NDMA produced is a function of the chemical functional group on the surface of the resin.

Occurrences of nitrosamines in chlorinated and chloraminated drinking water in three representative cities, China

“…The concentrations of NDMA in raw water from P1 were similar to those from P2, P3 and P5, but NDMA concentrations in finished water from P1 were higher than the others. These results are consistent with those of previous reports that chloramination may produce more NDMA than chlorination, and that NDMA concentrations in waters disinfected by chlorination are typically less than 10 ng/L for surface waters (Najm and Trussell, 2001). NDMA levels in finished water of P6 decreased to n.d. after O 3 treatment.…”

“…Published kinetic data also suggested that O 3 treatment reduced NDMA formation by oxidizing any secondary amines present in the source water (Zhao et al, 2008); however, this is based on the assumption that O 3 treatment removes DMA by completely mineralizing the secondary amine (Andrzejewski et al, 2008). Several alternative disinfectants such as O 3 are able to produce nitrosamines, but usually at lower concentrations than chloramines (Najm and Trussell, 2001;Andrzejewski et al, 2008). In contrast, UV and advanced oxidation processes have both been investigated as possible strategies to decrease or eliminate nitrosamine in water (Stefan and Bolton, 2002;Lee et al, 2005;Landsman et al, 2007).…”

“…Nitrosamines as emerging DBPs have become a concern of research recently, they have been shown to be present in meats, beers, pickles, tobacco smoke and may cause adverse effects on human health (IARC, 1978;Richardson, 2009). Nitrosodimethylamine (NDMA) was initially identified as a type of DBPs in drinking water in Ontario, Canada, in 1989(Charrois et al, 2007, and as a groundwater contaminant at a northern California aerospace facility in 1998 (Najm and Trussell, 2001). In the last 10 years, the majority of studies of DBPs have focused on NDMA because it is most frequently detected in drinking water.…”

N-Nitrosodimethylamine (NDMA) as a Drinking Water Contaminant: A Review

“…The two-step mechanism elucidated by Mitch and Sedlak (2002a) and Valentine (2002a, 2002b) is consistent with observations (Najm and Trussell, 2001;Berger et al, 2002;Najm and Ma, 2002;Wilczek et al, 2002) that the use of monochloramine in water treatment greatly increases NDMA formation. Because NDMA formation is slow (Mitch and Sedlak, 2002a;Mitch et al, 2003), the use of monochloramine to maintain a chlorine residual can result in increasing concentrations of NDMA within the distribution system.…”

New disinfection by-product issues: emerging DBPs and alternative routes of exposure

“…Nitrosodimethylamine (NDMA) is recognized as a probable human carcinogen, and until recently, concerns about NDMA primarily stemmed from its presence in food, beverages, consumer products, contaminated groundwater (from the use of rocket fuel), and polluted air (e.g., tobacco smoke) (Mitch et al, 2003). However, it has recently become evident that NDMA is also a drinking water DBP, which could make human exposure more widespread (Jobb et al, 1992;Graham et al, 1995;Kohut and Andrews, 2002;Andrews and Taguchi, 2000;Najm and Trussell, 2001). NDMA has primarily been found in chloraminated drinking water, where the nitrogen in monochloramine (NH 2 Cl) is incorporated into the structure of the NDMA by-product formed (Choi and Valentine, 2002).…”