Impact/Purpose:

Determine the actual concentrations of suspected health-impacting DBPs produced using non-chlorine disinfectants, how often they occur, under what conditions they are formed, and their fate and transport in the distribution system.

Description:

Due to concerns over trihalomethanes (THMs) and other halogenated by-products that can be formed during chlorination of drinking water, alternative disinfectants are being explored. 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 has reduced the permissible level of THMs in drinking water to 0.080 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 using these alternative disinfectants. As a result, there is significant uncertainty over the chemicals that people drinking this water are exposed to. These alternative disinfectants may produce compounds as or more harmful than those produced by chlorine. This project represents the extramural part (cooperative agreement) of the nationwide DBP occurrence study. Approximately 600 DBPs that have been reported previously in the literature were evaluated by expert toxicologists and prioritized according to probable adverse health effects. The 'top 50' DBPs resulting from the prioritization were included in this nationwide occurrence study in order to determine at what levels these DBPs are present, how often they occur, and under what conditions they are produced. These DBPs will also be followed throughout the potable water distribution system so that it can be determined whether these DBPs make it to the tap (and at what levels) or whether they are hydrolyzed/otherwise transformed into other chemicals during transport. After analytical methods are optimized for extracting and analyzing these DBPs, treated drinking water will be collected from different parts of the U.S. where different disinfectants are used (chlorine, chloramine, ozone, chlorine dioxide). The results of this study will be used to target future health effects research on those suspect DBPs that have the highest actual exposure probability.

Record Details:

Record Type:PROJECT

Start Date:10/01/1999

Completion Date:09/30/2002

OMB Category:Other

Record ID: 18291

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Project Information:

Progress :Completed task on 9/30/02. Nationwide DBP Occurrence Study was completed and an EPA report written (APM 65). High priority DBPs were measured in drinking water samples collected across the U.S., and new DBPs were also identified in this effort. Important results of this study include the finding of high priority DBPs at significant levels (similar to other regulated DBPs); finding that the use of alternative disinfectants actually increased the formation of many of these DBPs (e.g., trihalonitromethanes, MX and analogs, iodo-THMs, and haloaldehydes; and identifying iodo-acids as DBPs for the first time.

Relevance :This research is important to determine what chemical DBPs people are actually exposed to or could be exposed to through their drinking water when using non-chlorine disinfection technology. This is the first study to expand our knowledge on the occurrence of DBPs beyond those that are currently regulated. This study obtains actual critical concentration and fate and transport information for high priority DBPs, for which there is no available information. It is also the first study to focus efforts on DBPs that are a priority according to probable adverse health effects. Therefore, this study will provide the most focused information to date on DBPs of possible health risk from both chlorine and alternative disinfection technologies. This work relates to Drinking Water Disinfection, which is one of ORD's six high-priority areas, and it relates to Goal 2--Clean and Safe Water (2.1.7 Safe Drinking Water Research--By 2003, provide a stronger scientific basis for future implementation of the Safe Drinking Water Act).

Clients :Office of Water (OGWDW), contact: Jennifer McLain.

Research Component :M/DBP (DBP)

Risk Paradigm :EXPOSURE

Project IDs:

ID Code :none

Project type :ORD-DW Plan

ID Code :3741

Project type :OMIS