Public Citizen Health Research Group v. Tyson
796 F.2d 1479, 254 U.S. App. D.C. 253 (1986)
Rule of Law:
An occupational safety and health standard regulating toxic materials must be supported by "substantial evidence," require a threshold finding of "significant risk" to workers, and be "reasonably necessary and appropriate" to remedy that risk, while also setting the standard that "most adequately assures, to the extent feasible," that no employee will suffer material health impairment.
Facts:
- Ethylene oxide (EtO) is a chemical widely used in manufacturing processes and in the sterilization of hospital instruments.
- In 1968, the American Conference of Governmental Industrial Hygienists (ACGIH) recommended a long-term permissible exposure limit (PEL) of 50 parts EtO per million parts air (ppm) as an eight-hour time-weighted average (TWA).
- By 1977, the National Institute for Occupational Safety and Health (NIOSH) concluded that a 75 ppm short-term exposure limit (STEL) was necessary, in addition to the long-term PEL, due to studies showing EtO exposure alters cell genetic material.
- In 1979, further studies revealed a possible connection between EtO exposure and leukemia, leading ACGIH to consider a lower PEL of 10 ppm.
- In 1981, ACGIH lowered its recommended PEL to 10 ppm, then to 5 ppm, and by June 1982, recommended a 1 ppm PEL due to new animal studies showing carcinogenic hazards.
- Workers in hospital sterilization are particularly susceptible to EtO exposure when purging sterilization chambers, risking exposure to the chemical even after the process is imperfectly completed.
- Exposure patterns for EtO are often characterized by low background levels with intermittent, high-concentration bursts.
- OSHA's proposed rule included both a 1 ppm PEL and a STEL, but after review by the Office of Management and Budget (OMB), the final rule omitted the STEL.
Procedural Posture:
- In 1971, the Secretary of Labor adopted a 50 ppm PEL for EtO as a national consensus standard under 29 U.S.C. § 655(a).
- In January 1982, OSHA issued an advance notice of proposed rulemaking regarding the EtO standard, inviting comments.
- Public Citizen Health Research Group sued OSHA (then headed by Auchter) in the United States Court of Appeals for the District of Columbia Circuit, objecting to OSHA's lack of progress on promulgating an EtO standard.
- The D.C. Circuit, in Public Citizen Health Research Group v. Auchter, 702 F.2d 1150 (D.C.Cir.1983) (per curiam), ordered OSHA to propose a rule by April 1983 and finalize it within a year.
- OSHA complied by publishing a proposed rule suggesting a 1 ppm PEL (replacing the 1971 standard of 50 ppm) and a short-term exposure limit (STEL).
- OSHA held public hearings on the proposed rule in July 1983.
- After being prodded by Public Citizen due to continued delays, OSHA stipulated that it would complete the rulemaking by June 15, 1984.
- On June 14, 1984, OSHA had a final rule (providing for a 1 ppm PEL and a 10 ppm STEL), which it transmitted to the Office of Management and Budget (OMB) for review pursuant to Executive Order No. 12,291.
- OMB questioned several aspects of OSHA’s final rule, especially the STEL, stating it was unsupported by reasonable risk assessment.
- Notwithstanding OMB’s objections, OSHA published as a final rule only the long-term 1 ppm PEL, but reserved judgment on the STEL, reopening the record for comments on its desirability.
- On January 2, 1985, OSHA issued its final rule declining to impose a STEL.
- Petitioner Public Citizen Health Research Group challenged OSHA’s decision not to issue the STEL and argued that OMB’s role in these proceedings was unlawful.
- Petitioner Association of Ethylene Oxide Users (AEOU) also petitioned the D.C. Circuit for review, arguing that OSHA’s decision to issue the 1 ppm PEL was unsupported on the record.
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Issue:
1. Is OSHA's final rule establishing a 1 ppm permissible exposure limit (PEL) for ethylene oxide (EtO) supported by substantial evidence in the record, and does it adequately address the significant health risks posed by EtO, as required by the OSH Act and the Benzene decision? 2. Is OSHA's decision not to issue a short-term exposure limit (STEL) for ethylene oxide supported by substantial evidence in the record and a reasoned explanation, especially considering the OSH Act's mandate to assure the safest feasible working conditions?
Opinions:
Majority - McGowan, Senior Circuit Judge
Yes, OSHA's final rule establishing a 1 ppm permissible exposure limit (PEL) for ethylene oxide (EtO) is supported by substantial evidence in the record, as the agency made a sufficient finding of significant risk and demonstrated that the PEL is reasonably necessary and appropriate to remedy that risk to the extent feasible. The court applied the "substantial evidence" test, acknowledging its unique application to hybrid agency rulemaking involving complex scientific data. Citing Industrial Union Department, AFL-CIO v. American Petroleum Institute (Benzene), the court affirmed that OSHA must make a threshold finding that the health risk is "significant" and that the standard is "reasonably necessary and appropriate." OSHA's determination that EtO causes cancer, genetic damage (mutagenic and cytogenic effects), and reproductive problems was supported by substantial evidence from both epidemiological studies (e.g., Morgan, Hogstedt I & II, Hemminki) and experimental animal studies (e.g., Bushy Run rat study, NIOSH rat and monkey study). The court found that while individual studies might have flaws, their cumulative impact was compelling, especially given that OSHA operated "on the frontiers of scientific knowledge." OSHA used a quantitative risk assessment model, based on the Bushy Run study, to estimate significant excess deaths at the prior 50 ppm PEL and 12-23 excess deaths per 10,000 workers even at the 1 ppm PEL. The court upheld OSHA's use of a linear, no-threshold model, finding it to be a "conservative assumption" supported by reputable scientific thought, consistent with the Benzene plurality's allowance for such assumptions and the "best available evidence" standard. The court rejected AEOU's challenge to the animal-to-human conversion factor, finding OSHA's method reasonable and consistent with scientific understanding. The court concluded that OSHA had complied with the OSH Act and the Benzene decision in promulgating the 1 ppm PEL, having thoroughly reviewed the evidence, estimated the risk, found it significant, and determined the 1 ppm PEL to be the lowest feasible limit. No, OSHA's decision not to issue a short-term exposure limit (STEL) is not supported by substantial evidence in the record, because the agency failed to adequately consider the interrelationship between the PEL and a STEL and did not provide a reasoned explanation for its assumption that the 1 ppm PEL would necessarily control short-term exposures sufficiently. The court affirmed OSHA's finding that the record did not establish a specific "dose-rate effect" (where short, high exposures cause disproportionately greater harm than equivalent total doses spread over longer periods). However, the court found OSHA's other justifications for omitting a STEL insufficient. OSHA reasoned that the 1 ppm PEL would sufficiently reduce significant risk and that compliance with the PEL would necessarily control short-term exposures. The court determined that this reasoning required an unstated, unsupported premise: that employers, in meeting the 1 ppm eight-hour time-weighted average (TWA) PEL, would in every case reduce short-term exposures to a point at or below the proposed 10 ppm STEL. The court pointed to evidence in the record suggesting exposure patterns often involve low background levels combined with high intermittent exposures (e.g., for minutes or an hour), which could still allow cumulative exposure to fall within a 1 ppm eight-hour TWA while individual short-term exposures significantly exceeded 10 ppm. Given that a significant health risk remained even at 1 ppm, and the OSH Act compels the agency to adopt feasible standards that further reduce risk, OSHA needed to either show that a STEL would have no effect on this remaining risk or that it was not feasible. Since feasibility was not contested, OSHA's failure to adequately explain why the PEL alone would control short-term exposures, despite evidence of high intermittent exposures, constituted a failure to "consider an important aspect of the problem," warranting a remand. The court declined to reach constitutional questions regarding OMB's participation because the statutory review of the STEL decision necessitated a remand.
Analysis:
This case reinforces the "substantial evidence" standard for reviewing OSHA's health and safety standards, particularly when the agency is operating on the "frontiers of scientific knowledge." It illustrates the importance of a thorough record and reasoned explanation for all aspects of a regulation, including decisions not to regulate. The court's remand on the STEL issue demonstrates that even when an agency successfully defends one part of a complex rule, it must provide comprehensive justification for all its decisions, particularly concerning the interrelationship of different regulatory components (like PEL and STEL) in mitigating significant risks. It highlights the judiciary's role in ensuring agencies adhere to their statutory mandates, even when facing scientific uncertainty.
