DBP in Drinking Water: Measures and Data
Why is there concern about disinfection byproducts (DBPs)?Some DBPs have been associated with cancers and adverse pregnancy outcomes. Long-term exposure to some DBPs has been associated with bladder, colon, and rectal cancer. Even low levels of some DBPs over time may be potentially harmful to fetuses. The expense of mitigating for DBPs may be prohibitive for smaller water systems. The number of DBPs grows as new methods of disinfection are developed.
How are DBPs tracked?Four classes of DBP chemicals—trihalomethanes, haloacetic acids, bromates, and chlorites—are tracked through state regulatory programs by the EPA. Most systems use chlorine and track the first two classes. DBPs are measured at multiple locations within each distribution system that delivers a community water supply. The EPA’s rules have become progressively more stringent since tracking began in 1979.
What can be done about DBPs to minimize public health risk?Limiting organic matter from surface water sources by filtration can reduce DBP concentrations in finished water. Water systems can monitor groundwater sources, when subject to seawater intrusion in wells or in specific geological circumstances, for elevated bromide levels prior to disinfection. More research is needed on emerging DBP compounds and on providing cost-effective ways to mitigate or avoid high DBP levels.
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