Some members of the Supreme Court wondered whether a federal occupational health standard could shut down whole industries. Others were concerned that the lack of a standard would kill workers. Chief Justice Warren E. Burger asked whether the government could ban cigarette smoking in workplaces.

The questions arose during a 1 1/2 hour oral argument on a ruling that an Occupational Safety and Health Administration standard for a jobsite exposure to a cancer-causing substance must pass a cost-benefit test.

Ruling, by the 5th U.S. Circuit Court of Appeals, ordered OSHA to set aside a standard for worker exposure, during an eight-hour day, to benzene, the 12th most widely used industrial chemical. An estimated 30,000 workers in petroleum and other industries are regularly exposed to airborne benzene particles.

To protect workers from nonmalignant diseases, employers in 1971 set a standard of 10 parts per million. Then came evidence that benzene causes blood cancer. Scientists generally agree that there is no known safe level of exposure to a carcinogen, and that the fact that something causes cancer may not be evident for about 20 years.

In 1977, after a hearing, Labor Secretary Ray Marshall set a new standard -- the one at issue in the case -- of one part per million. He took into account evidence that benzene causes, in addition to leukemia, an often fatal blood disease and genetic damage.

He acted under a 1970 law directing him to adopt standards "reasonably necessary or appropriate" to healthful employment. The law also says he must set the standard "which most adequately assures, to the extent feasible, on the basis of the best avialable evidence, that no employe will suffer material impairment of health" even from "regular exposure" throughout his working life.

Justice William H. Rehnquist repeatedly expressed concern that the law does not define "feasible," and, as a result might improperly authorize OSHA to legislate a definition.

For the government, however, William H. Alsup said that OSHA is "absolutely not" authorized to do anything it wants. The legislative history shows that Congress intended "feasible" to mean technologically and economically "achievable," said Alsup of the Office of the Solicitor General.

By contrast, Edward W. Warren of the American Petroleum Institute said Congress meant "reasonable and practical." He also termed the old 10-part-per-million standard "adequate."

Justice Lewis F. Powell Jr. asked if "feasible" means that OSHA could put out of business an "entire industry" or, in the case of the auto industry, two or three of the four major manufactures.

"we dont't contend we will shut down industries," Alsup said, "I'd like to get that ot right now." He emphasized that the government rejects both "absolutist views" and notions of "absolute protection."

He also said there's no dispute that the cost of meeting the one-part-per-million benzene standard is "clearly within the capability" of the approximatley 20 affected industries. Labor Secretary Marshall has put the cost at $266 million for engineering controls, plus outlays of up to $205 million in the first year and $34 million in each succeeding year.

Replying to other questions by Powell, Alsup said that once OSHA adopts a standard essential to a healthful workplace, it must prevail even if some companies go under. OSHA "cannot trade lives against dollars," Alsup said. The law prohibits "the survival of employers who don't give workers the protection they deserve," he added.

A key point in the 5th Circuit ruling was Marshall's inability to quantify the number of lives that would be saved by lowering the permissible benzene exposure to 1 part per million.

But George H. Cohen, arguing for the AFL-CIO'S Industrial Union Department, said the data for such a calculation don't exist, and will not exist for many years, partly because of the decades-long latency of cancer. This point elicited supportive questions and remarks from Justice Thurgood Marshall and Harry A. Blackmun.

And Justice John Paul Stevens, drawing an admission from the API's Warren that the 10-part-per-million exposure embodied a possibility of appreciable harm, told him. "If you win this case, someone may die as a result." Alsup, replying to the chief justice's question on worksite cigarette smoking, said OSHA is empowered to ban it if a ruling-making proceeding were to develop substantial scientific support for such a step. But he termed the prospect of a ban "very unlikely."