United States Environmental Protection Agency Office of Research and Development National Exposure Research Laboratory Research Abstract Government Performance Results Act (GPRA) Goal 2 Annual Performance Measure #202 Significant Research Findings: Method Development for the Determination of N-Nitrosodimethylamine (NDMA) in Drinking Water NDMA is an emerging drinking water contaminant that is of interest to EPA and the environmental community. Its presence in drinking water is a potential health concern, because the EPA's IRIS data base lists the concentration of NDMA required to result in a one in one million lifetime cancer risk to be only 0.7 ng/L. NDMA is produced by industrial sources, such as the manufacture of rocket fuel, but has also been identified as a potential disinfection by-product. The focus of NERL's research was to develop an improved analytical method for the analysis of NDMA in drinking water that was sensitive, specific and cost-effective. Existing methods for measuring NDMA in water are expensive and labor intensive, and some require the use of very large amounts of toxic solvents such as methylene chloride. In addition, the sensitivity of some existing methods is insufficient for conducting low-level monitoring. The method was developed for inclusion in EPA's Unregulated Contaminant Monitoring Rule, scheduled for proposal in 2005, in order for the EPA Office of Water to collect nationwide occurrence data on nitrosamines in drinking water and make a regulatory determination. If NDMA or other nitrosamines become regulated drinking water contaminants in the future, the method could also be used for compliance monitoring. The research goal was to develop a sensitive, selective and cost-effective method for measuring NDMA (and other additional nitrosamines.) The initial method sensitivity goal for NDMA was to demonstrate a Minimum Reporting Level (MRL) near 1 ng/L, a value as close as practically possible to the one in one million cancer risk concentration. Gas chromatography with chemical ionization tandem mass spectrometry (GC/MS/MS) was investigated for the chromatographic separation and detection steps, because of its sensitivity and its specificity. To avoid the use of large volumes of toxic organic solvents, solid phase extraction techniques were investigated for the extraction of nitrosamines. A variety of commercially available solid phase sorbents proved to be ineffective for NDMA, given its high water solubility. However, the research demonstrated that coconut Scientific Problem and Policy Issues Research Approach ------- charcoal was both efficient as the solid phase sorbent and provided the additional benefit of being inexpensive. The approach involved developing procedures for (1) sample collection, preservation, shipping and handling, (2) extraction and concentration of the target analytes from aqueous solution, (3) separation of the analytes chromatographically, and (4) detection and quantitation. Results and The analytical method developed by NERL has overcome many of the Impact difficulties related to the current methods (poor sensitivity, specificity and cost-effectiveness, complexity and use toxic solvents), and provides a well documented and standardized method for the measurement of NDMA and other nitrosamines.. The analytical method developed from this research can be used to measure NDMA and six additional nitrosamines in drinking water samples. The MRL achieved for NDMA was 1.6 ng/L, and ranged from 1.2 to 2.1 ng/L for the other method analytes. This method is an improvement over other published methods for nitrosamines in the following ways: (1) the sample preparation steps are simple, efficient, and relatively inexpensive while using only small amounts of toxic solvents, (2) use of the tandem mass spectrometer as the detector provides positive identification of all method analytes without the use of additional confirmatory techniques, and 3) the quality control steps in establishing and verifying the MRL ensure both precision and accuracy in the measurement of trace amounts of the method analytes. These improvements will meet EPA's data quality objectives in the collection of nationwide occurrence data to support regulatory decision making for nitrosamines, while reducing the cost of analysis. Publications resulting from this research: Munch, J.W. and M. V. Bassett, "Methods for Emerging Contaminant Groups: Explosives and Nitrosamines", Proceedings: American Water Works Water Quality Technology Conference, Philadelphia, PA, Nov. 3, 2003. Munch, J.W. and M.V. Bassett, "U.S. EPA Method 521: Determination of Nitrosamines in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography with Large Volume Injection and Chemical Ionization Tandem Mass Spectrometry (MS/MS)", National Exposure Research Laboratory, Microbiological and Chemical Exposure Assessment Research Division, Chemical Exposure Research Branch, 26 W. Martin Luther King Dr., Cincinnati, Ohio, 45268-1564. Future Research Due to the success of the method development, no further research is planned at this time. This method, EPA Method 521, is available for use as the required analytical method in the Office of Ground Water and Drinking Water's upcoming proposal for the Unregulated Contaminant Monitoring Research Collaboration and Research Products ------- Rule. When finalized, this regulation will require a nationwide monitoring survey of selected CCL contaminants and emerging drinking water contaminants, including NDMA. Occurrence data from this survey will be used in the decision making process for the possible regulation of NDMA. Contacts for Additional Information Questions and inquiries can be directed to: Jean W. Munch USEPA National Exposure Research Laboratory 26 W. Martin Luther King Dr. Cincinnati, OH 45268-1564 Phone: (513) 569-7465 e-mail: munch.iean@epa.gov Funding for this project was through the U.S. EPA'S Office of Research and Development, National Exposure Research Laboratory, and the work was conducted by the Microbiological and Chemical Exposure Assessment Research Division. ------- |