Chlorine and the Disinfection Byproducts Rule

Chlorine and the Disinfection Byproducts Rule

July 17, 2008

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For many years, the U.S. Environmental Protection Agency (EPA) has attempted to develop standards to regulate disinfection byproducts, a group of microbial contaminants that result when public water is purified with chlorine. The EPA is working on congressionally mandated deadlines to issue a series of rules to regulate these contaminants. According to the General Accounting Office (GAO), now the Government Accountability Office, the first of two stages of these rules will cost $700 million a year. Because the science used to justify these rules is very weak, it is likely that the public will pay billions in exchange for little or no benefit. Because the rules cause reduced use of chlorination to keep water supplies clean, the public may suffer adverse health impacts. 

The EPA proposed a rule in 1994,2 but Congress extended the deadline until November 1998. The EPA issued stage 1 of the rule on schedule. The law required the EPA to finalize stage of the rule by May 2002, but it did not actually finalize the rule until January 2006. For each regulated contaminant under the Safe Drinking Water Act (SDWA), the EPA usually specifies a maximum contaminant level goal (MCLG), which represents the level of a contaminant that the EPA ideally wants to allow in drinking water. The EPA uses the MCLG as a guide in setting the enforceable standard, the maximum contaminant level (MCL). The MCL represents the amount of a contaminant that systems may legally allow in tap water. In 1998, controversy emerged when the EPA issued its first set of standards for disinfection byproducts. The EPA set a zero MCLG and a 0.08 MCL for a group of four disinfection byproducts called “total trihalomethanes,” of which chloroform is one. A federal court reversed the MCLG for chloroform.