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THE NEXT GENERATION OF DRINKING WATER DISINFECTION BY-PRODUCTS AND HEALTH ISSUES
Citation:
RICHARDSON, S. D. THE NEXT GENERATION OF DRINKING WATER DISINFECTION BY-PRODUCTS AND HEALTH ISSUES. Presented at Invited Seminar at the University of Alberta, Edmonton, AB, CANADA, March 03, 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 an effort to obtain new information on unregulated DBPs, we initiated a Nationwide Occurrence Study to quantify priority DBPs (those predicted by toxicology experts to have an adverse health effect) to determine how often they occur and at what levels. Various analytical methods, including mass spectrometry, were used to quantify these priority DBPs and identify new ones. An important and unexpected finding of this study was that many of the priority DBPs (e.g., iodo-trihalomethanes, trihalonitromethanes, MX analogs, and dihaloaldehydes) were formed at higher levels with the use of alternative disinfectants (ozone, chloramines, chlorine dioxide) as compared to chlorine. In addition, five iodo-acids were identified for the first time. One of these iodo-acids-- iodoacetic acid--is more genotoxic and cytotoxic than other DBPs currently regulated, and there is information that points to increased iodo-DBP formation with the use of chloramines. A follow-up iodo-DBP occurrence study is currently in progress, where these iodo-acid and iodo-trihalomethane DBPs are being quantified in chloraminated drinking waters across the United States (and one site in Canada). In addition, a new EPA study (the Four Lab Study), which involves the chemical and toxicological evaluation of complex drinking water mixtures treated with chlorine and alternative disinfectants, will be briefly discussed, along with other important new health effects information.