The Environmental Protection Agency, faced with important medical evidence against relaxing the standard for lead in gasoline and only mixed support from the industry it thought wanted the change, is trying to extract itself from what has become another agency public relations fiasco.

EPA sources stress that no action has been taken, and that a final decision on an issue as controversial as this one probably will be made personally by Administrator Anne M. Gorsuch. And she isn't talking.

But the sources say whatever EPA does will be designed to defuse the sharp criticism it has received from the health community, some of the government's top health experts, environmentalists and 31 members of Congress.

The EPA also must figure out how to deal with two studies it commissioned and its staff analysis, which all concluded that hundreds of thousands of children could get lead poisoning if the standards were weakened.

"It's going to be hard to relax those standards now, unless serious flaws are found" in the studies, one EPA source said. Another said, "They the Office of Management and Budget couldn't have picked a worse thing to target . Lead has been studied more than just about any other toxic."

Relaxing lead standards "would put us in favor of harming the health of thousands of children" at a time when the EPA is trying to fight an image that it has become soft on polluting industries and dangerous substances.

Children are particularly susceptible to lead contamination because they metabolize lead more easily and store it longer than adults.

Lead was widely used as an anti-knock additive in gasoline until 1979, when EPA began requiring that the lead content be phased down to the current standard of 0.5 grams per gallon. Small refiners were exempted from the standards until this October. When the Reagan administration came into office, the lead standard was one of the first regulations that caught the eye of the Presidential Task Force on Regulatory Relief.

Several small refiners complained that they would be put out of business if they had to conform to the 1982 standards. Large refiners complained that the exemptions for small refiners placed them at a competitive disadvantage and said the standard should be eliminated entirely.

The OMB told the EPA to do something. In October, the EPA staff drafted a proposed rule, which set out a variety of options it could take, from making no changes to eliminating the standard. The EPA cleared the rule in November, but it was not released until February, because the OMB had objected that the EPA had not gone far enough.

"We told OMB, 'You guys don't understand. Lead isn't good for people. We're not going to put our head on the political guillotine,' " one EPA source said. Instead the EPA published the rule, as it had wanted to originally.

Shortly after that the EPA decided that it lacked the authority to penalize those who illegally put leaded gasoline in cars designed for unleaded gasoline. The EPA also began reviewing the air-quality criteria for lead, the basic standard establishing what level is safe.

Meanwhile, the Occupational Safety and Health Administration started re-evaluating the lead exposure standard for work places. OSHA also proposed eliminating the lead standard for the longshoreman industry, at the urging of exporters of lead ore.

Those developments exacerbated the fears that EPA's proposal had aroused. Scientists such as Dr. Herbert L. Needleman, a University of Pittsburgh professor and physician who has studied lead poisoning for years, protested to Congress that lead standards, particularly the gasoline ones, should not be weakened.

Rep. Toby Moffett (D-Conn.) wrote a letter to Gorsuch, signed by 30 other House members, that was highly critical of EPA's proposal.

The Natural Resources Defense Council announced that it would sue the EPA for failing to enforce the air quality standards for lead. Meanwhile, large refiners such as Exxon Co. didn't offer the strong support for eliminating the standard that the Reagan administration had expected.

The large refiners said they could live with the current standard as long as it applied to small refineries too. Even some small refineries, like Asamera Oil Inc., complained that continuing the exemption for small refineries would penalize those firms that had complied already.

In the midst of the controversy, the executive committee of the EPA science advisory board voted to advise Gorsuch on the lead issue, even though Gorsuch aides had said that its advice wasn't wanted.

At recent public hearings held by EPA, Dr. Jerome F. Cole, director of environmental health for the Lead Industries Association, argued that there are no public health reasons why federal restrictions on lead in gasoline should be retained.

But studies for the EPA by the Mitre Corp. and by Dr. Irwin Billick, the Housing and Urban Development Department's lead expert, concluded that there is a strong correlation between lead levels in gasoline and lead poisoning in children.

In a memo summarizing the reports, Dr. Joel Schwartz, of the EPA's Office of Policy and Resource Management, said, "Lead has long been known to have adverse health effects, particularly upon children . . . . "

Even the cost-benefit analysis required by President Reagan for major regulations didn't support a change. Schwartz calculated that eliminating the standard would save industry about $100 million a year. But he estimated that it would cost anywhere from $140 million to $1.4 billion to treat the additional 200,000 to 500,000 children that would get lead poisoning.