CASE STUDIES AND VAlUE OF RESEARCH
How Foundation Research on Nitrosamines has Benefited
the Water Industry
Stuart W. Krasner, Principal Environmental Specialist, Metropolitan Water District of Southern California
Nitrosamines are emerging contaminants in water where there is health and regulatory concern. Since the 1970s,
numerous researchers have reported on the presence of various nitrosamines in many foodstuffs (e.g., beer, meat, and
cheese products preserved with nitrite) and consumer products (e.g., tobacco smoke and latex products). Nitrosamines
can cause cancers in a wide variety of animal species and the USEPA classified a number of them as probable human
carcinogens. They have 10-6 risk levels at low nanogram-per-liter (ng/L) levels.
In the 1990s, N-nitrosodimethylamine (NDMA) was found in drinking water in Ontario, Canada and in California.
Initially, its presence was associated with industrial contamination. Soon after, it was found to be a by-product of
drinking water treatment, in particular at plants that used certain (polyamine) polymers and/or chloramines. In addition,
it was found in treated wastewater. As a result, Ontario set a maximum acceptable concentration for NDMA at 9 ng/L
and California established notification levels for three nitrosamines (NDMA, N-nitrosodiethylamine [NDEA], and
N-nitrosodipropylamine [NDPA]) at 10 ng/L each. Although there is currently no federal standard for nitrosamines in
drinking water, the USEPA included several nitrosamines in the Unregulated Contaminant Monitoring Rule 2 (UCMR2)
and on the Contaminant Candidate List 3 (CCL3). Preliminary results indicate that NDMA and other nitrosamines are in
a number of U.S. drinking waters. Thus, it is likely that this class of chemicals will be regulated in the future.
To provide valuable information to the water industry on this emerging class of chemicals, the Water Research
Foundation has been funding research on NDMA and other nitrosamines since 2000. The first completed project,
Factors Affecting the Formation of NDMA in Water and Occurrence (2006, order #91063/project #2678),
included a survey of drinking water, recycled water, and treated wastewater in the United States and Canada.
This groundbreaking project established that NDMA could be formed via a non-nitrosation mechanism during
chloramination and that certain amine-based polyelectrolytes and anion-exchange resins used in drinking water
treatment were important sources of NDMA precursors.
Subsequently, the Foundation has supported a wide range of projects to examine the sources of nitrosamine precursors
in water and the occurrence, formation, and control of nitrosamines, which is providing the water industry with critical
information. One report, Contribution of Wastewater to DBP Formation (2008, order #91206/project #2948),
showed that wastewater treatment plants could be an important source of nitrosamines and their precursors. With
both planned and unplanned reuse, this has become a substantial issue for drinking water treatment plants, especially
in arid parts of the United States, as well as in highly urbanized regions. This study included the development of a
reactivity-based formation potential (FP) test to determine the levels of nitrosamine precursors in treated wastewater
and in drinking water, photolysis studies to examine the degradation of nitrosamines in receiving waters, and the fate
and transport of nitrosamine precursors in effluent-impacted water supplies.
The Foundation funded research conducted in Germany and Switzerland, Strategies for Minimizing Nitrosamine
Formation During Disinfection (2006, order #91209/project #2979), to support international research on identifying
different ways of controlling nitrosamines. This report demonstrated that NDMA precursors could be naturally removed
through riverbank filtration or artificial groundwater recharge and that NDMA precursors could be destroyed or
transformed during pre-oxidation (with ozone or chlorine). Moreover, this innovative completed project examined a
wide range of amine-based chemicals to determine their likelihood as NDMA precursors. For example, ranitidine, a
pharmaceutical used as an antacid, had a much higher conversion efficiency to NDMA than dimethylamine (DMA).