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CHLORINATED VS. CHLORAMINATED DRINKING WATER: TOXICITY-BASED IDENTIFICATION OF DISINFECTION BY-PRODUCTS USING ESI-MS AND ESI-MS/MS
Citation:
RICHARDSON, S. D., F. G. CRUMLEY, M. J. PLEWA, E. D. WAGNER, T. H. MIZE, AND R. ORLANDO. CHLORINATED VS. CHLORAMINATED DRINKING WATER: TOXICITY-BASED IDENTIFICATION OF DISINFECTION BY-PRODUCTS USING ESI-MS AND ESI-MS/MS. Presented at 19th Annual Tandem Mass Spectrometry Workshop, Lake Louise, AB, CANADA, November 29 - December 02, 2006.
Impact/Purpose:
(1) Use a toxicity-based approach to prioritize and identify DBPs that show the greatest toxic response. (2) Comprehensively identify DBPs formed by different disinfectant regimes for the 'Four Lab Study'. (3) Determine the mechanisms of formation for potentially hazardous bromonitromethane DBPs.
Description:
Drinking water disinfection by-products (DBPs) are of concern because some epidemiologic studies have shown that some DBPs are associated with cancer or adverse reproductive/developmental effects in human populations, and other studies have shown that certain DBPs cause similar health effects in laboratory animals. As a result, the U.S. EPA has regulated several DBPs. However, more than 500 DBPs have been reported in drinking water for which little or no occurrence and health data exist. In addition, there is almost no information on high molecular weight DBPs (>1000 Da), which are indicated to comprise >50% of the total organic halide (TOX) from chlorinated drinking water. None of these high molecular weight halogenated by-products have ever been precisely identified, and there is no information on potential toxicity of this high molecular weight fraction. There is also very little information regarding highly polar DBPs, which are missed by most commonly used analytical techniques.
The goal of this research is to use a bio-assay directed approach to focus identification work on the most toxicologically important DBPs. To this end, drinking water is being collected from full-scale treatment plants that use chlorine, ozone, chlorine dioxide, and chloramines as disinfectants, and this drinking water is being fractionated initially according to molecular size (through the use of ultrafiltration membranes). Previous results from our research have shown that most of the toxicity resides in the <1000 Da fraction, with significant toxicity also in the 1000-5000 Da fraction. New research is further refining these fractions and investigating molecular weight fractions of <500, 500-1000, 1000-3000, 3000-5000, and >5000 Da. A mammalian cell genotoxicity/cytotoxicity assay is being used to determine the toxicity of each fraction and to direct the identification work. Gas chromatography (GC) with high resolution mass spectrometry (MS) is being used to identify the lower molecular weight, non-polar drinking water DBPs; ESI-MS and ESI-MS/MS with a linear ion trap-Fourier transform (FT) mass spectrometer are being used to obtain structural information on high molecular weight and highly polar DBPs. Tentative identifications of new chloro-bromo DBPs will be presented, along with new toxicity information on the five molecular weight fractions collected.