Author(s)

S. D. Richardson

Abstract

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. As a result, we recently conducted a nationwide study to obtain occurrence data for unregulated, high priority DBPs that were predicted to cause adverse health effects. The goal of this work was to determine how often and at what levels these DBPs occurred, so that DBPs could be prioritized for future health effects studies. In addition to providing important quantitative information on these unregulated, priority DBPs, we discovered that many of the priority DBPs were formed at higher levels with alternative disinfectants than with chlorine. Also, new iodo-acid DBPs were identified for the first time—and one of these—iodoacetic acid has been shown to be more genotoxic than all of the other haloacid DBPs currently regulated. New research includes toxicological and quantitative occurrence measurements for the five iodo-acids identified. In addition, another 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. 1 Introduction Drinking water disinfection by-products (DBPs) are of concern because some epidemiologic studies have shown that some DBPs are associated with cancer or

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