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SRA Risk Science & Law Specialty Group

AFL-CIO v. OSHA: Admitting Scientific Opinion as Scientific Evidence

Can a government agency set permissible exposure levels (PELs) for 428 toxic substances without specific, substantial evidence, relying instead on consensus levels among scientists?

AFL-CIO v. OSHA, 965 F.2d 962 (11th Cir.1992) involved the Occupational Safety and Health Administration's (OSHA's) Air Contaminants Standard, where the agency set PELs for 428 potentially toxic substances at once. This was accomplished by "generic" rulemaking; substances were grouped into 18 categories by their primary health response, such as neuropathic effects, sensory irritation, and cancer. The agency explained:

[I]t would take decades to review currently used chemicals [individually] and OSHA would never be able to keep up with the many chemicals which will be newly introduced in the future.

The 11th Circuit, however, believed the PEL for each substance must stand independently; each PEL must be supported by substantial evidence and be accompanied by adequate explanation. The court adhered to the U.S. Supreme Court's standard adopted in the Benzene case, 100 S.Ct. at 2870-71, which holds that the agency has . . .

no duty to calculate the exact probability of harm [or] to support its finding that a significant risk exists with anything approaching scientific certainty.

OSHA is required to at least estimate actual risk associated with a particular substance.

Also at issue was OSHA's use of safety factors to make a standard stricter than the levels at which available evidence shows no significant health risk. The basis is the possibility the evidence is incorrect or incomplete, thus conceding that existing evidence does not adequately show the extent of risk. The agency merely observed how it is "customary" to set a PEL by applying a safety factor between 10 and 100 to the lowest level at which adverse effects had been observed.

The court cited the lesson of Benzene that OSHA may use assumptions only to the extent they have some basis in reputable scientific evidence. If a standard should be more stringent than even a conservative interpretation of the existing evidence, then additional evidence must be acquired to support a more protective limit.

The 11th Circuit vacated and remanded the rule for OSHA to make specific findings with respect to each substance. OSHA had based its rule on epidemiological or toxicological studies or, in their absence, simply adopted what it called "consensus levels" among scientists. The court applied the "harder look" doctrine to meet a statutory requirement in the Air Contaminants Standard of "substantial evidence," instead of the more deferential arbitrary and capricious standard under the Administrative Procedures Act (APA).

This case presents at least two major implications for risk analysis: (1) Regulation by classes of chemicals cannot be supported using a "generic" approach to risk assessment; and (2) the convention of using safety factors in risk assessment to superimpose conservative health risk policy on scientifically derived LOAELs (Lowest Observable Adverse Effects Levels) for noncarcinogens may not survive judicial review.

[Contributed by Wayne Roth-Nelson]

CLASSIFICATION: JUDICIAL REVIEW; REGULATORY AGENCY CHEMICAL RISK ASSESSMENT; SUFFICIENCY OF EVIDENCE FOR REGULATION

Copyright © 1999 by Tec-Com, Inc.
Last modified July 29, 1999.