In a move that could open up a major regulatory battlefield, federal officials are cautiously trying to determine how far industry can go in barring women from jobs that endanger their ability to bear healthy children.

At issue is the growing practice of some companies -- particularly those that make or handle certain chemicals and products containing lead -- to exclude fertile women from jobs where they may come in contact with teratogens. eA teratogen is a substance that can cause defects in a developing embryo.

The debate is both wide-ranging and complex, evoking questions that range all the way from who should decide which is more important, a woman's job or her future children, to whether a fetus may be covered by workman's compensation.

In addition to industry and federal job safety regulators, the issue has drawn the attention of the Equal Employment Opportunity Commission, various women's groups, unions and medical experts with sometimes conflicting opinions on potential reproductive hazards in the workplace.

"It's a real morass," said David McClintik, a Shell Chemical Co. official who heads that company's task force exploring ways to deal with the problem.

"We are hiring unprecedented numbers of women for jobs that were traditionally held by men," McClintik said.

"We're trying to balance the rights of women workers with the whole question of safety. At this point we just don't have any guidelines on whether a woman has the right to waive responsibility for the fetus. It can be argued that the fetus has rights of its own."

Last month, in the first federal move to protect worker fertility and the health of unborn children, the Occupational Health and Safety Administration stepped gingerly into the fray.

OSHA cited the American Cyanamid Co. for what it said was Cyanamid's corporate policy of requiring women at its Willow Island, W. Va., paint plant to be sterilized if they worked with lead. Five women at the plant said they were sterilized last year to keep their jobs in the plants' lead pigment section. Lead is a known teratogen, according to federal experts.

American Cyanamid denied it had forced the women to be sterilized. But a spokesman for the firm said it is company policy to exclude women from jobs that involve contact with teratogenic substances.

"If there's scientific evidence that there is a danger to a woman's fetus, then naturally we are going to keep her out of a dangerous situation," the spokesman said.

Also at the heart of concern to companies is the still-unresolved issue of how much legal and financial liability a company might have to bear if one of its female workers who has been exposed to teratogens in the workplace loses a child or has a baby with a birth defect.

McClintik said Shell, which has several hundred women in its petrochemical operations area, is leaning toward a policy of excluding fertile women from jobs around teratogens if there is no certainty that they would not be exposed.

Other companies such as Hercules, at its missile fuel plant in Utah; Gulf Resources and Chemical Corp., at its Bunker Hill lead smelter in Idaho; and allied Chemical Corp. have similar policies.

Eula Bingham, assistant secretary of labor for health and safety and the head of OSHA, said in an interview that her agency purposely confined itself in the American Cyanamid case to the narrow issue of work safety and health.

"The issue of job discrimination, where women may not be allowed into a workplace, is very closely intermingled with the concept we addressed," Bingham said. "It still sits there waiting to be addressed by other governmental agencies with legal enforcement power in that area."

Federal equal employment officials estimate at least 100,000 jobs involving contracts with potential teratogens are now closed to women, either because of corporate policies or through subtle channeling of women away from those positions.

"This is a practice forced on us to the extent that we are becoming a chemical society," said Eleanor Holmes Norton, head of the EEOC.

EEOC and several other federal agencies, including OSHA, are working on the first set of federal guidelines for employers faced with the exclusion issue, said Norton.

Now before the commission are two cases involving nine women excluded from jobs involving hazardous substances such as teratogens, Norton said. The cases, which won't be decided before the guidelines are completed, are likely to set a precedent for similar cases, she said.

Whatever the outcome, some unions, such as the rubber workers, auto workers, and oil, chemical and atomic workers, contend that industries are already using exclusionary procedures to avoid the expense or bother of cleaning up their manufacturing operations.

Industry critics also charge that regardless of the intention being excluding women, the procedure is discriminatory.

Anthony Mazzocchi, director of health and safety for the Oil, Chemical and Atomic Workers International Union, which represents the women at the American Cyanamid plant at Willow Island, said OSHA's citation of the company is significant.

"The decision basically says alter the workplace, not the workers," Mazzocchi said.

While the EEOC commissioners have not made any decision on the cases before that federal panel, Norton said there is evidence that some companies may be trying to "shortcut" safety issues by excluding women.

"The fact is," she said, "that some of them are taking exclusionary steps without a scintilla of evidence to support those actions."

The commission's guidelines, said Norton, are likely to require that employers shoulder the burden of proof that a hazard exists for fertile women even after they have made an effort to clean up a workplace. In such cases, she said, exclusion of women may be necessary.

Perhaps an even more difficult question still lies ahead, said the EECC chief. "I think the real issue is the failure to focus on whether some of these chemicals can affect the male sperm. Then defects will be transported to the fetus no matter what we do about women," she said.

The United Auto Workers union, which is pressing General Motors to drop its policy of excluding women from jobs involving contact with lead, is also exploring the danger of male reproductive hazards as well.

"There are lots of substances that are hazardous to the reproductive processes of men as well as women and we want to see a new corporate position on both sexes on this issue in the future," said Judith Scott, a UAW attorney.

But the issue of such workplace effects on men is not as clear as it is for women.

Dr. Jeanne Manson, a reproductive toxicologist at the University of Cincinnati Medical School, said her work and others' indicates that males are affected by what she called "spermatotoxic" industrial material. Such chemicals, she said, can cause infertility or genetic damage to male sperm, which can then cause fetal defects.

Other experts, however, disagree with Manson's thesis. Dr. Godfrey Oakley, chief of the birth defects branch at the federal Center for Disease Control in Atlanta, said that researchers are able to pinpoint only about 5 percent of birth defects to any environmental cause. Another 10 to 15 percent can be attributed to genetic problems, he said.

"That leaves us with up to 80 percent remaining," said Oakley, "and at this point we don't have the slightest idea why they happen."