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. 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.
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. 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.