Detection of N-nitrosamines in water supplies is an environmental and public health issue because many N-nitrosamines are classified as probable human carcinogens. Some analytical methods are inadequate for detecting N-nitrosodimethylamine (NDMA) at low ng/L concentrations in water due to poor extraction efficiencies and nonselective and nondistinctive GC/MS electron ionization techniques. Development of a selective, sensitive, and affordable benchtop analytical method for eight N-nitrosamines, at relevant drinking water concentrations was the primary objective of this project. A solid-phase extraction method using Ambersorb 572 and LiChrolut EN was developed in conjunction with GC/MS ammonia positive chemical ionization (PCI). Ammonia PCI shows excellent sensitivity and selectivity for N-nitrosamines, which were quantified using both isotope dilution/surrogate standard and internal standard procedures. Method detection limits for all investigated N-nitrosamines ranged from 0.4 to 1.6 ng/L. Applying our extraction method to authentic drinking water samples with dissolved organic carbon concentrations of 9 mg/L, we were able to detect N-nitrosodimethylamine (2-180 ng/L) as well as N-nitrosopyrrolidine (2-4 ng/L) and N-nitrosomorpholine (1 ng/L), two N-nitrosamines that have not been reported in drinking water to date. With high recoveries of standards and analytes, the described internal standard method offers a valuable new approach for investigating several N-nitroso compounds at ultratrace levels in drinking water.

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Removal of organic micropollutants from wastewater during secondary treatment followed by reverse osmosis and UV disinfection was evaluated by a combination of four in-vitro cell-based bioassays and chemical analysis of 299 organic compounds. Concentrations detected in recycled water were below the Australian Guidelines for Water Recycling. Thus the detected chemicals were considered not to pose any health risk. The detected pesticides in the wastewater treatment plant effluent and partially advanced treated water explained all observed effects on photosynthesis inhibition. In contrast, mixture toxicity experiments with designed mixtures containing all detected chemicals at their measured concentrations demonstrated that the known chemicals explained less than 3% of the observed cytotoxicity and less than 1% of the oxidative stress response. Pesticides followed by pharmaceuticals and personal care products dominated the observed mixture effects. The detected chemicals were not related to the observed genotoxicity. The large proportion of unknown toxicity calls for effect monitoring complementary to chemical monitoring.

Since the 1974 discovery of trihalomethanes as disinfection by-products (DBPs) in drinking water, the regulatory and public health focus has been primarily directed at halogenated compounds, even though it is well established that chlorination and chloramination also produce non-halogenated DBPs. Specific halogenated DBPs that could reasonably explain the correlation of some adverse health outcomes with consumption of disinfected drinking water in a number of epidemiologic studies have yet to be identified. We therefore explored an emerging class of non-halogenated DBPs, N-nitrosamines, which warrant consideration given public health concerns regarding possible correlations of bladder cancer with exposure to chlorinated drinking water. We developed a dual media (Ambersorb® 572 and LiChrolut® EN), off-line, solid-phase extraction method that utilized a modified commercially-available extraction manifold combined with our previous GC–MS ammonia positive chemical ionization (PCI) quantitative method for analyzing N-nitrosamines in drinking water. We surveyed 20 Alberta municipal drinking-water distribution systems for the presence of N-nitrosodimethylamine (NDMA) and seven other N-nitrosamine species. Analytical results revealed the occurrence of NDMA (up to 100 ng/L) as well as two other N-nitrosamines (N-nitrosopyrrolidine and N-nitrosomorpholine) within select Alberta drinking water supplies.Key words: Alberta, chloramination, disinfection by-products, distribution system, drinking water, N-nitrosamines, NDMA, public health, survey.