Seven years after Congress and the Environmental Protection Agency ordered refiners to reduce the amount of lead in the gasoline they produce, the old debate over these rules is being recycled--with a new twist. Opponents now say the rules have done their job and can be safely jettisoned in the interests of profit and productivity.

The debate reopened in August when Vice President Bush targeted the rules for review, citing the expensive technological burden they will impose on small refineries, starting next year. Larger refiners, knowing the review could lead to the rules' elimination, have joined the chorus against them. Changes may be made in the next few months.

Now that more than half of the nation's gasoline supply is unleaded, the issue for large refiners is how much lead the other half may contain. Allowing higher lead levels reduces larger refiners' production costs. Small refiners, about to lose their exemption from the rule's most stringent provisions, want to avoid investing millions in new machinery. Environmentalists still argue that airborne lead can impair the health and learning ability of children, particularly in congested urban areas.

As the battle is joined again, the old combatants have armed themselves with new scientific and economic studies and adjusted their rhetoric to fit the new political landscape.

Hank Hankla, Washington lobbyist for the American Petroleum Refiners, the small refiners' organization, cites two reports when making his case for repeal. One, from the Energy Department, says refineries must use 100,000 extra barrels of crude oil a day to abide by the rules; the second, by E.I. duPont de Nemours and Co., predicts that even without the rules, airborne lead levels would meet federal standards almost everywhere in the nation by 1984.

Eric Goldstein of the Natural Resources Defense Council counters with a 1979 medical study showing that 3,229 first- and second-graders in suburban Boston who were exposed to a significant amount of lead tended to be slower learners and more unruly than their peers.

"These rules are the mainstay, the guardian of the urban environment in terms of lead pollution," said Goldstein.

Lead has been used in gasoline for years as a quick and cheap means of raising octane levels, increasing fuel efficiency and keeping engines from knocking. And it has long been known both that lead is poisonous, and that many inner-city children have excessive amounts of lead in their systems.

As a 1980 National Academy of Sciences report states: "Growing evidence suggests that commonplace exposures to lead in urban environments may be associated with detrimental effects on the intellectual development and behavior of children." What is not as clear, as refiners and their supporters point out, is how inner-city children are exposed to lead: by breathing exhaust fumes or by eating dirt and lead paint chips.

At the moment, about 120 million pounds of lead--most of it from car exhausts--are discharged into the atmosphere annually, down from about 450 million pounds a year in 1971. Airborne lead would double to about 240 pounds annually if the rules were revoked, according to Rob Weissman, a special assistant in EPA's office of air, noise and radiation.

All sides agree that increased use of unleaded gasoline has been a major factor in getting lead out of the air. But the shift to unleaded gasoline had less to do with these so-called "lead phasedown" rules than with rules requiring automakers to reduce carbon monoxide pollution by installing catalytic converters on cars built after 1974. Because the devices can be ruined by leaded gasoline, the cars are required to use unleaded fuel.

From a refiners' point of view, this was an economic incentive to make more unleaded fuel, an incentive that would remain even if the lead rules were eliminated. But if the rules were revoked, refiners could double the lead content in the rest of their gasoline, reverting to the pre-1974 levels and cutting their production costs.

Small refiners in rural areas, however, say the issue for them isn't cost as much as survival. Their larger counterparts have already made the investment in the expensive technology needed to make higher-octane unleaded gasoline. But they have had little economic incentive to produce unleaded gas, since much of their gasoline goes to the fuel tanks of trucks and tractors.

Their exemption ends Oct. 1, 1982, according to the rules. If nothing changes, Hankla says, these firms must invest between $10 million and $20 million in reformers, the large cylindrical devices that chemically raise the octane levels of unleaded gasoline.

That investment, not to mention the 10 to 20 percent increase in annual operating costs, would bankrupt many small refiners, Hankla claims. "In any business you don't want to spend millions of dollars that will have no return for you," Hankla said.

"We believe that it's a wasteful approach to overregulate something in a redundant manner when you have such a tremendous potential for savings on the other side," said Urvan Sternfels, whose National Petroleum Refiners Association represents both large and small refiners. "No one questions that lead is a problem for public health," but the rise of the catalytic converter and the technological changes in refineries complying with the rule, have taken care of the lead exhaust problem, he said.

Not so, said Goldstein of the NRDC. "For the vast majority of urban America the major lead problem is motor vehicles," he said. Public health and environmental officials, he said, have determined lead is an "environmental menace" and "auto emissions are the most significant source we can identify and regulate."