Court rejects EPA chloroform rule

Court rejects EPA chloroform rule
June 1, 2000

Bonner R. Cohen

Bonner R. Cohen is a senior fellow with the National Center for Public Policy Research, a position... (read full bio)

The U.S. Court of Appeals for the District of Columbia ruled on March 31 that the U.S. Environmental Protection Agency violated the Safe Drinking Water Act by failing to use the "best available peer¬reviewed science" in establishing the Maximum Contaminant Level Goal (MCLG) for chloroform, a byproduct of drinking water disinfection.

Writing on behalf of the court, Judge Stephen F. Williams noted, "Finding the agency's December 1998 rule adopting a zero MCLG for chloroform to be arbitrary and capricious and in excess of statutory authority, we vacate the rule. . . . In promulgating a zero MCLG for chloroform, EPA openly overrode the 'best available scientific evidence', which suggests that chloroform is a threshold carcinogen."

As for EPA's arguments on behalf of a zero standard for chloroform, Williams wrote: “The fact that EPA has arrived at a novel, even politically charged outcome is of no significance," adding that the agency's explanation represented pointless "semantic somersaults."

The case was one of the most closely watched in recent regulatory history, because of the way in which EPA dealt with the science of chloroform. Agency scientists had carried out an exhaustive review of toxicological data on chloroform going back 20 years. Based on that review, the scientists recommended EPA adopt a standard of 300 parts per billion (ppb). The scientists' conclusion, which recognized a threshold level below which human exposure to chloroform poses only a minuscule risk, was hailed by scientists outside the agency, even drawing praise from the Society of Toxicology, the largest professional association of toxicologists in the world.

That praise, however, quickly disappeared when, in December 1998, EPA announced it was proposing a zero standard.

From the perspectives of science and public health, EPA's decision was baffling. Chloroform is created when drinking water is chlorinated to remove microbial pathogens. The presence in drinking water of trace amounts of chloroform and other so-called disinfectant by-products is the inevitable result of the water purification process.

Water suppliers have come to see these trace elements as posing a far lower risk to public health than the pathogens that would otherwise remain in the drinking water. Since chlorination was adopted by water systems across the U.S. in 1908, it has resulted in the virtual elimination of such deadly water-borne diseases as cholera, typhoid, dysentery, and hepatitis A.

Since EPA was not able to produce a credible scientific argument in support of its decision, political motives were suspected. Environmental groups, led by the Natural Resources Defense Council (NRDC), vigorously opposed anything other than a zero standard for chloroform and urged the agency to "reject the unproven and probably incorrect hypothesis that there is a threshold for its carcinogenic effect, a theory that ignores human evidence of chlorination byproducts' carcinogenicity."

Acknowledging that there is little or no risk below a certain threshold is to undermine one of the key tenets of modern environmentalism which, as the NRDC statement makes clear, denies the existence of such thresholds. In the end, EPA cast its lot with the environmentalists and ignored the findings of its own scientists. The court's ruling rejects EPA's position and reintroduces science into the environmental regulatory process.


Bonner R. Cohen is a senior fellow at the Lexington Institute in Arlington, Virginia.


For more information

The Court of Appeals’ seven-page decision in Chlorine Chemistry Council and Chemical Manufacturers Association v. Environmental Protection Agency is available through PolicyBot. Request document #2315750.

Bonner R. Cohen

Bonner R. Cohen is a senior fellow with the National Center for Public Policy Research, a position... (read full bio)