Disinfection By-Products


Characterization of DBPs

Fate and Transport of DBPs in the Environment

Monitoring in the Environment

Exposure Pathways

Reducing Exposure


Potential Health Effects

Haloacetic Acids




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Strategies for Reducing Exposure to Disinfection Byproducts

More than 98% of water treatment systems in the U.S. use a form of chlorine for disinfection.6 Chlorine is not the only disinfectant that can produce DBPs, but it is the main chemical responsible for the formation of THMs and HAAs. The use of chlorine has many advantages over other disinfection methods: it is easy to use, relatively inexpensive, maintains a residual through the distribution system, and reduces bad odors and tastes. There has been some suggestion of the use of chloramines (formed from combining chlorine with ammonia) instead of chlorine for water disinfection. Chloramines are a weaker disinfectant, but more stable, and do not react as readily with organic matter thereby reducing the potential formation of certain DBPs.4 It is reasonable to say, however, that chlorine will continue to be the most widely used disinfectant in water treatment for the foreseeable future. One reason is that the EPA has not yet identified a causal link between exposure to DBPs and cancer, reproductive or developmental effects. Also, chlorine has been recognized as an “effective defense against many biological warfare agents”6. Since the signing of the 2002 Bioterrorism Act, more attention has been focused on the safety of public water supplies, and chlorine disinfection is an integral part of these safety measures.

For these reasons, exposure reduction becomes a personal responsibility for individuals concerned with the possible risks posed by DBPs. The use of bottled drinking water may be one way to reduce exposure to DBPs by ingestion. The Natural Resources Defense Council (NRDC) conducted a study testing many brands of bottled water and the level of contaminants found in each. This study included the concentration of Total trihalomethanes (TTHMs), which are often used as an indicator of overall DBP levels. For individuals interested in investigating bottled-water alternatives, an extensive table summarizing the results of the study can be found at the NRDC website (http://www.nrdc.org/water/drinking/bw/appa.asp). Activated carbon filters (such as the ones used in BRITA pitchers) are not effective in removing any of the four major DBPs regulated by the EPA. Additionally, there are many other home water treatment devices that can be used to remove various substances from water used for showering and bathing. These devices range from point-of-entry systems (to treat most or all of the water entering a particular residence) to point-of-use systems (to treat the water coming out of a particular shower head, for example). The NSF Consumer website has explanations of the various types of home water treatment systems, as well as a list of devices that are certified to reduce DBPs (www.nsfconsumer.org).


4. NSF International Consumer Information (2003). Disinfection Byproducts. [Online] http://www.nsfconsumer.org/events/disinfection_byproducts.asp

5. U.S. Environmental Protection Agency (2003). Disinfection Byproduct Health Effects. [Online] http:///www.epa.gov/enviro/html/icr/dbp_health.html

6. Water & Wastes Digest Water Quality Products. Disinfection Part 2: Is Chlorine Still the Answer? January 2003 [Online] http://www.wwdmag.com/wwd/index.cfm;jsessionid=80302469361065105167419?