Industrial Union Dept., AFL-CIO v. American Petroleum Institute (The Benzene Case)

Acting under OSHA's directive to set standards that most adequately assure, to the extent feasible, that no employee suffers material health impairment, the Secretary of Labor set a benzene exposure standard at the lowest technologically feasible level, reasoning that no safe exposure level for the known carcinogen could be determined; the Secretary did not make a specific finding that existing, higher exposure levels posed a significant health risk, instead stating benefits from lowering exposure were "likely" to be "appreciable." The American Petroleum Institute (plaintiff) challenged the standard, and the Fifth Circuit held it invalid; the Supreme Court granted certiorari.