Impact/Purpose:

Develop analytical methods to quantify iodinated DBPs in chloraminated drinking waters and to collaborate with CDC which is developing methods to measure iodo-THMs in human blood/urine.

Description:

Several drinking water treatment plants in the United States have altered their treatment methods and adopted alternative disinfectants in order to comply with a U.S. Environmental Protection Agency (EPA) regulation that limits the level of trihalomethanes (THMs) in drinking water to 0.08 ppm. The alternative disinfectants currently being used in the United States (including ozone, chloramine, and chlorine dioxide) are effective for killing harmful microorganisms in drinking water, and they do not produce significant levels of THMs. However, there is only very limited information concerning what chemical disinfection by-products (DBPs) are produced from these alternative disinfectants. As a result, there is significant uncertainty over the chemicals that people drinking this water are exposed to.

Results of the Nationwide DBP Occurrence Study revealed the presence of iodinated acids as DBPs for the first time in chloramine-treated drinking water. One of these (iodoacetic acid) has been shown to be more genotoxic than the haloacetic acids that are currently regulated and to cause neural tube defects in mouse embryos at low doses. Iodo-THMs were also found to be at their highest levels in chloraminated drinking water in the Nationwide Study, and they have been predicted to be highly toxic (planned for study at NHEERL). Increased formation of iodinated DBPs in chloraminated drinking water has also been recently predicted in the literature. Since many drinking water treatment plants have switched from chlorine to chloramines, additional exposure and toxicity information is needed on iodoacids to characterize the potential risk to humans. As a result, this task sets out to quantify iodo-DBPs (iodo-acids and iodo-THMs) in chloraminated drinking waters, where they are expected to be maximized. Because no quantitative data exists for iodo-acids, there is an immediate need for quantitative occurrence data. The Centers for Disease Control and Prevention (CDC) has agreed to collaborate on this project; they will develop an analytical method for measuring iodo-THMs in drinking water and in human blood and urine. ERD will develop an analytical method for measuring the iodo-acids in drinking water. The CDC has an interest in quantifying iodo-THMs in human blood and urine to expand on their previous human exposure work with the four regulated THMs. The CDC has conducted human exposure experiments previously and would provide funding to obtain the needed human biological samples.

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