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SRA
Risk Science & Law Specialty Group |
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| 1999-2000
Online Casebook (Second Edition)
Leather Industries of America, Inc. v. EPA Can EPA regulate a contaminant by placing a cap on allowable concentrations based not on risk calculations but on a level lower than 99 percent of the values found in a survey of that contaminant's source? Petitioners, including four different publicly and privately owned waste treatment operations, sought judicial review of standards issued by EPA for the use or disposal of sewage sludge from pre-discharge sewage and wastewater treatment facilities. Part of the petition turned on EPA's interpretation of the Clean Water Act (CWA), which directed EPA to: . . . identify those toxic pollutants which . . . may be present in sewage sludge in concentrations which may adversely affect public health or the environment, . . . and to specify management practices and numerical criteria . . . adequate to protect public health and the environment from any reasonably anticipated adverse effects of each pollutant, . . . In this review [40 F.3d 392 (D.C.Cir. 1994)], EPA argued that it would be a permissible interpretation of the statute to use, as a pollutant concentration cap, a numerical criterion—the 99th-percentile (99th-%ile) concentration from a descriptive survey of pollutant concentrations actually present in current sludge output nationwide. As an outcome of studies by experts of 48 pollutants in sewage sludge, the agency elected to initially regulate 10 heavy metals in sludge applied to land as a soil conditioner and fertilizer. Then the agency surveyed and selected the metal concentrations not exceeded by 99 percent of sludge samples. Risk-based concentrations (RBCs) also were calculated. The sludge concentration caps proposed were either the 99th-%ile or RBC, whichever is more stringent. But petitioners argued where the 99th-%ile was applied instead of the RBC—that is, to chromium and selenium, it was not risk-based and therefore exceeded the authority of the CWA. The U.S. Court of Appeals held that neither of EPA's two proffered reasons provided adequate justification for EPA's interpretation. First, the court rejected EPA's explanation that, when the 99th-%ile concentration is lower than the allowable risk-based concentration, it offers a "margin of safety" necessary to ensure "adequate protection." The court held that the statute required risk-based regulations, and that the 99th-%ile concentration was not risk-based. Second, the court rejected EPA's explanation that use of the 99th-%ile would prevent "backsliding" from current practices. The court held that "anti-backsliding" regulations are legitimate only if the target standards are themselves risk-based. Thus, EPA's interpretation of the statutory language was not permissible. EPA's many applications of the 99th percentile, as often dictated for default exposure parameters in screening risk assessments (SRAs), are a distortion of objectively determined risk that elevates policy considerations like anti-backsliding over sound science. [Contributed by Vern Walker/Edited by Wayne Roth-Nelson] |
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