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Under the Safe Drinking Water Act, there are Maximum Contaminant Level Goals (MCLG) and Maximum Contaminant Levels (MCL). An MCLG for a particular contaminant is a non-enforceable, health-based goal. The SDWA requires MCLG to be set at a level at which no known or anticipated adverse effect on human health occurs, allowing for an adequate margin of safety. MCLs are enforceable standards that must be established as close to the respective MCLG as is feasible.
The 1996 amendment to the SDWA revised the procedure to be used by U.S. EPA in setting MCLG and MCL to help assure that U.S. EPA uses the best available scientific information. 42 U.S.C. § 300g-1(b)(3)(A) now states that "to the degree that an Agency action is based on science, the Administrator shall use . . . the best available, peer-reviewed science and studies conducted in accordance with sound and objective scientific practices."
Chloroform is one of four compounds, together classified as Total Trihalomethanes (TTHM), that are disinfection byproducts of chlorination. In 1994, U.S. EPA proposed a zero MCLG for chloroform based on data that it acts as a probable human carcinogen and a finding of an absence of data to suggest a threshold level below which there would be no such effect. U.S. EPA’s methodology for inferring risk at exposure levels for which it had no data was linear extrapolation from cancer incidence inferred at exposures where it had data.
Facing a deadline for establishing its Disinfectants/ Disinfectants Byproducts Rule, in 1998 U.S. EPA concluded that chloroform in fact was not linear; that is, exposure below some threshold level would not impose a risk of cancer. Nevertheless, U.S. EPA retained the existing MCLG of zero, which was based on the prior assumption that chloroform was linear.
The Chlorine Chemistry Council and others petitioned the federal Court of Appeals to review and vacate the 1998 rule setting an MCLG of zero for chloroform, asserting that U.S. EPA violated the best available scientific evidence requirement of Sec. 300g-1(b)(3)(A).
The Court has held that U.S. EPA’s 1998 rule adopting an MCLG of zero for chloroform was arbitrary and capricious, beyond statutory authority and void. Chlorine Chemistry Council v. Environmental Protection Agency, 2000 WL 301187, 206 F.3d 1285 (D.C. Cir. 2000).
Basically, the Court agreed that U.S. EPA violated the statutory mandate under the 1996 SDWA amendments to use best available scientific evidence. The Court found that in 1998, U.S. EPA had available to it a report of a panel of experts, which was subject to independent peer review and was convened by U.S. EPA, that concluded that chloroform was unlikely to be carcinogenic below a certain dose. The panel recommended a non-linear margin of exposure methodology. U.S. EPA agreed with the panel. However, in its final rule issued in December 1998, it retained the zero level on the ground that additional deliberations were needed that could not be completed before the November 1998 statutory deadline.
The Court rejected U.S. EPA’s excuse for adopting a zero MCLG for chloroform despite then existing scientific evidence that chloroform is a threshold carcinogen. "In promulgating a zero MCLG for chloroform EPA openly overrode the ‘best available’ scientific evidence, which suggested that chloroform is a threshold carcinogen." 2000 WL 301187, p. 5. The Court said that even if U.S. EPA planned additional deliberations, there was no reason to act against its own scientific evidence in the meantime. "EPA cannot reject the ‘best available’ evidence simply because of the possibility of contradiction in the future by evidence unavailable at the time of action—a possibility that will always be present." Id.
U.S. EPA argued that since the final MCL for TTHMs was not changed, its decision to maintain the MCLG for chloroform at zero pending further study was reasonable, given that the MCLG had no enforceable effect. The Court disagreed. It cited a prior decision, International Fabricare Institute v. EPA, 972 F.2d 384 (D.C. Cir. 1992) in which the Court found that MCLGs were linked to greater liability under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) where clean-up may have to attain MCLG levels.
In fact, the Court in the instant case stated that U.S. EPA has established chloroform clean-up goals far below the MCL for TTHMs and practically at zero. "Thus EPA’s actual practice belies its claims here as to the inconsequentiality of the chloroform MCLG." Id. at p. 4. Petitioners asserted that they face liability for clean-up of chloroform at Superfund sites. Thus, the Court stated, "we find it at least substantially probable that a zero MCLG, as compared with a nonzero one, will expose them to higher clean-up costs." Id. at p. 5.
Regardless, the Court concluded, even if a zero MCLG had no effect, "we fail to see why it would justify EPA’s disregard of its own scientific findings." Id. at p. 6.
There are, perhaps, some lessons to be learned from the Courts decision. It illustrates the importance of questioning the scientific basis for levels of both MCLGs and MCLs that are established after the 1996 SDWA amendments. Given concerns over the cost of infrastructure improvements forecasted as necessary to satisfy more stringent standards, perhaps water utilities have an obligation to mitigate costs by questioning standards that may not be well founded.
Ironically, water utilities, who must monitor their operations for compliance with standards, wisely also may have to monitor U.S. EPA’s operations for compliance with theirs.
Dan Kucera is a partner in the law firm of Chapman and Cutler, 111 W. Monroe St., Chicago, Illinois 60603–4080, (312) 845–3000.