Under OSHA, the Department of Labor was made responsible for developing standards to provide safe or healthful employment and places of employment. Further standards were mandated for toxic materials or harmful physical agents under section 6(b)(5). OSHA stated that the Secretary should set the standards which most adequately assures to the extent feasible that no employee will suffer material impairment to health. The Secretary took the position that wherever toxic carcinogens were to be regulated that no such exposure could be deemed safe exposure and that section 6(b)(5) required him to set the safe exposure limit at the lowest technologically feasible level that will not impair the viability of the industries regulated. It was determined that there was a causal connection between benzene and leukemia and as such, the Secretary set the exposure level on airborne concentrations at one ppm. On appeal, the Fifth Circuit held that the Secretary was under a duty to determine whether the benefits expected from the new standard bore a reasonable relationship to the costs that it imposed. The Supreme Court granted certiorari.