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OCCURRENCE AND TOXICITY OF IODO-ACID DISINFECTION BY-PRODUCTS IN CHLORAMINATED DRINKING WATER
Citation:
RICHARDSON, S. D., J. J. ELLINGTON, F. G. CRUMLEY, J. J. EVANS, M. J. PLEWA, AND E. D. WAGNER. OCCURRENCE AND TOXICITY OF IODO-ACID DISINFECTION BY-PRODUCTS IN CHLORAMINATED DRINKING WATER. Presented at Symposium "Safe Drinking Water: Where Science Meets Policy.", Chapel Hill, NC, March 16 - 17, 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:
As part of a recent Nationwide Disinfection By-Product (DBP) Occurrence Study, iodo-acids were identified for the first time as DBPs in drinking water disinfected with chloramines. The iodo-acids identified included iodoacetic acid (IAA), bromoiodoacetic acid, (E)-3-bromo-3-iodo-propenoic acid, (Z)-3-bromo-3-iodo-propenoic acid, and (E)-2-iodo-3-methylbutenedioic acid. There is concern about these new iodo-acid DBPs because mammalian cell cytotoxicity and genotoxicity studies have revealed that IAA is highly cytotoxic and genotoxic, with a genotoxicity potency 2X higher than bromoacetic acid, the most genotoxic of the regulated haloacetic acids (HAAs). Also, many drinking water treatment plants in the United States have switched from chlorine to chloramines for treatment. New evidence indicates that iodinated DBPs may be increased in formation in chloraminated vs. chlorinated drinking water. The goal of this work was to develop an analytical method to quantify these five iodo-acids in drinking water, measure their occurrence in drinking waters treated with chloramination, and investigate the toxicity of the four synthesized iodo-acids (beyond IAA). An initial sampling of chloramine drinking water treatment plants conducted in May 2005 revealed IAA in all finished waters; bromoiodoacetic acid in 4 of the 5 finished waters; and the other iodo-acids in one of the finished waters. The highest level was 1.7 ppb (for IAA) in waters from two cities. The study was then expanded in the fall of 2005 to include 22 cities - 21 cities in the U.S. and one in Canada--that use chloramination. These samples are currently being analyzed, and data from these samples will be presented, along with new toxicity information.