Natural Resources Defense Council v. Environmental Protection Agency
381 U.S. App. D.C. 373, 529 F.3d 1077 (2008)
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Rule of Law:
Under Section 112(f) of the Clean Air Act, a lifetime excess cancer risk greater than one-in-one-million from a source of hazardous air pollutants triggers a mandatory residual risk rulemaking by the EPA. However, this figure does not impose a substantive standard; the EPA retains the discretion to determine an 'ample margin of safety' by applying its pre-1990 Benzene standard, which permits risks up to 100-in-one-million and allows for the consideration of cost.
Facts:
- Facilities in the synthetic organic chemical industry emit hazardous air pollutants, including known, probable, or possible human carcinogens.
- In 1990, Congress amended the Clean Air Act to require a two-stage process for regulating these pollutants.
- The first stage required the EPA to set technology-based standards, known as Maximum Achievable Control Technology (MACT) standards, which the agency did for the synthetic organic chemical industry in 1994.
- These 1994 MACT standards did not reduce the lifetime excess cancer risk for the most exposed individuals to a level below one-in-one-million.
- The second stage required the EPA to assess the remaining 'residual risk' and, if necessary, promulgate new standards to provide an 'ample margin of safety to protect public health.'
- The Act also required the EPA to conduct a separate technology review every eight years to assess developments in control technologies.
- After conducting its residual risk assessment and technology review, the EPA determined that the existing 1994 standards already provided an ample margin of safety and that no new technological developments necessitated a revision.
Procedural Posture:
- The Environmental Protection Agency (EPA) conducted a residual risk and technology review for the synthetic organic chemical manufacturing industry as required by the Clean Air Act.
- In 2006, the EPA published a final rule in the Federal Register, reaffirming the existing 1994 emissions standards and declining to impose stricter requirements.
- The Natural Resources Defense Council and the Louisiana Environmental Action Network (petitioners) filed a petition for review of the EPA's final rule in the U.S. Court of Appeals for the District of Columbia Circuit.
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Issue:
Does section 112(f) of the Clean Air Act require the EPA to promulgate residual risk standards that reduce lifetime excess cancer risks from carcinogenic pollutants to less than one-in-one-million for the most exposed individual?
Opinions:
Majority - Silberman
No. Section 112(f) of the Clean Air Act does not require the EPA to reduce residual cancer risks to a mandatory one-in-one-million level. The statute's reference to a one-in-one-million risk serves as a trigger that compels the EPA to conduct a rulemaking, but it does not dictate the substantive content of the resulting standards. The court reasoned that the controlling substantive standard is the 'ample margin of safety' requirement, which, under § 112(f)(2)(B), explicitly incorporates the EPA's interpretation from its 1989 National Emission Standards for Hazardous Air Pollutants for Benzene. That Benzene standard established a two-step approach where the EPA first determines an 'acceptable' risk (presumptively up to 100-in-one-million) and then sets the final standard with an 'ample margin of safety,' which allows for the consideration of costs and other factors. Because the EPA's decision to reaffirm its existing rule was consistent with the Benzene standard, its interpretation of the statute was reasonable and entitled to Chevron deference.
Analysis:
This decision solidifies the EPA's discretionary authority in the risk-based phase of regulating hazardous air pollutants under the Clean Air Act. It clarifies that the one-in-one-million cancer risk benchmark is a procedural trigger for rulemaking, not a substantive floor that standards must meet. By upholding the incorporation of the more flexible 1989 Benzene standard, the court affirms that the EPA can deem risks as high as 100-in-one-million acceptable and may consider costs when setting final standards. This precedent grants the agency significant latitude, making it more difficult for environmental groups to compel stricter regulations based solely on residual risks exceeding the one-in-one-million level.
