## Facts

- OSHA, acting under the Occupational Safety and Health Act of 1970, issued a rule lowering the permissible exposure limit for benzene from 10 ppm to 1 ppm and restricting dermal contact with benzene solutions.
- Benzene is widely used in industry; OSHA concluded benzene exposure can cause leukemia.
- OSHA treated benzene as a carcinogen with no safe threshold and applied an “as low as feasible” approach without determining the level of risk at 10 ppm.
- Industry groups challenged the standard on pre-enforcement review, arguing OSHA had not shown a significant risk at 10 ppm or that a 1 ppm limit would meaningfully reduce risk, and that OSHA’s approach effectively required near-zero risk regardless of cost.
- The Fifth Circuit invalidated the standard, reasoning OSHA had exceeded its authority by failing to show the standard was “reasonably necessary or appropriate” and by construing the Act to require a virtually risk-free workplace.
- The Supreme Court granted review and affirmed.

## Issues

1. Whether, before issuing a toxic-substance standard under OSH Act § 6(b)(5), OSHA must determine—based on the best available evidence—that the existing exposure level poses a “significant risk” of material health impairment.
2. Whether construing § 6(b)(5) to require the lowest feasible exposure for carcinogens without a significant-risk determination raises serious limits on delegated agency power.
3. Whether OSHA acted within its statutory authority by adopting a 1 ppm benzene limit without first finding significant risk at 10 ppm.

## Decision

- The Court affirmed the judgment invalidating OSHA’s benzene standard.
- A plurality held that OSHA must make a threshold finding that workers face a significant risk of material health impairment at the existing or regulated exposure level.
- The plurality concluded the administrative record did not support a finding that 10 ppm exposure created a significant risk, nor did it adequately show that reducing the limit to 1 ppm would reduce a significant risk.
- The plurality construed the statute to avoid reading it as authorizing regulation to eliminate even trivial risks and noted constitutional concerns with an interpretation lacking meaningful limiting principles.
- A concurrence agreed a significant-risk finding is required and emphasized the relevance of feasibility and cost considerations in selecting a standard.
- A separate concurrence would have found the delegation problem more directly.
- The dissent would have upheld the rule, reading the statute to allow OSHA to require stringent controls for carcinogens based on feasibility and protective judgment under scientific uncertainty.

## Legal Principles

- An OSHA health standard must address a nontrivial workplace danger; a threshold finding of “significant risk” is required before imposing more stringent exposure limits under § 6(b)(5).
- § 6(b)(5)’s instruction to set the standard that “most adequately assures, to the extent feasible” protection operates within the Act’s requirement that standards be “reasonably necessary or appropriate” under § 3(8).
- OSHA may act amid scientific uncertainty, but must at least qualitatively or quantitatively assess risk at the relevant exposure level and justify that the risk is significant, not merely speculative.
- Statutory interpretation may be limited to avoid serious constitutional doubts where an agency’s reading would confer effectively unbounded discretion.

## Conclusion

The Court held that OSHA cannot tighten toxic-exposure limits solely on the premise that any exposure to a carcinogen is harmful; before regulating, the agency must find, based on the best available evidence, that existing exposure levels pose a significant risk of material health impairment, and OSHA’s benzene 1 ppm standard was invalid for lack of that threshold determination.


Indus. Union Dep’t, AFL-CIO v. Am. Petroleum Inst., 448 U.S. 607 (1980)