An article yesterday incorrectly identified the Center for Science in the Public Interest as a Ralph Nader group.

Twenty years ago, hundreds of children were showing up in hospitals across the country wracked with convulsions, in comas, some even dying, poisoned by eating lead paint chips.

That doesn't happen much anymore. Since 1972, when the federal government launched a program to prevent lead poisoning, the percentage of screened children found to have dangerous levels of lead in the bloodstream has dropped from 11 to 4 percent.

But budget cuts and policy changes by the Reagan administration have caused even the government's own advisers to worry that the problem could return. Among the changes:

* The $10 million-a-year lead screening program has been folded into a block grant to the states for maternal and child health services. The overall total was cut by 27 percent--to $373 million--for fiscal 1982, and the lead screening now must compete with programs for crippled children, adolescent pregnancy services, maternal care and others.

* Next year the administration wants to fold that block grant into a giant $1 billion grant that would include the Women, Infants and Children (WIC) nutritional program for the poor. WIC alone cost the government $934 million this year, so the total funds available would be cut by $300 million.

* The Housing and Urban Development Department, which is required by law to research the extent of lead poisoning in urban areas and ways to control it, has just RIFfed its last researcher dealing with lead poisoning, even though a federal judge ruled last month that the agency is not adequately enforcing a law designed to remove hazardous paint from public housing units.

* The Environmental Protection Agency has proposed allowing refiners to increase the amount of lead they can put in gasoline. Research has shown that lead in gasoline is emitted into the air, becoming a major contributor to lead poisoning.

* The Occupational Safety and Health Administration has granted or proposed exemptions from its lead standards for several industries, and is considering relaxing regulations protecting workers from lead exposure. Critics say those moves could have an impact on workers' children, through the lead dust carried home or the effect of exposure on fetal development.

The federal government's withdrawal from lead screening is "to deny many, many thousands of children the protection of these programs" when they need screening more than ever, said Kirk Johnson of the Center for Science in the Public Interest, a Ralph Nader group that has organized a National Coalition for Lead Control.

The number of children being screened may already have dropped. According to the Centers for Disease Control, 92,769 children were screened during the first quarter of this fiscal year compared with 126,049 in the like quarter last year, although the states may be neglecting to report screening rather than stopping it.

Dr. Herbert Needleman, a University of Pittsburgh psychiatrist who has conducted major research into the effects of lead poisoning, said, "It's highly unlikely that states are going to pick up the slack. When there's competition for block grant money, there's plenty of people who can yell louder than mothers of lead-exposed kids."

Johnson noted that some states have still been drawing on old grants and thus haven't been hit by the full impact of the cuts. But some localities have already been forced to cut back.

In Paterson, N.J., where lead poisoning is the seventh highest of any U.S. city, the screening office has fired two of its three health aides and reduced doctor's hours from six to two hours a week. The agency expects the number of children screened this year to drop from 3,800 to 2,000.

Akron and Cleveland have been forced to stop a door-to-door campaign informing parents about lead poisoning and urging them to bring the children in for screening. And in St. Louis, officials have slashed the screening staff in half and expect to screen only two-thirds as many children as last year's 18,000.

"If you stop screening, these children will not be found at an early stage of poisoning, and they will come in with coma and convulsions, the way we used to see them in the '50s and '60s," said Dr. Jane Lin-Fu, a pediatric consultant to the Health and Human Services Department, which administers the block grants.

Because the effects of low-level lead poisoning aren't readily apparent, "you can turn your head the other way and the disease will disappear," Lin-Fu said. "It will reappear later as mental retardation, epilepsy, blindness or cerebral palsy."

James Corrigan, associate director of the HHS office that administers the grants, said it was too early to tell whether the dire predictions would come true. "The states could spend their entire allotment on lead-based paint poisoning if they chose to do so, or they could cut it out," Corrigan said. "I have no information that the states will not do a bang-up job."

Although lead-based paint is no longer used for residential interiors, and the percentage of children with dangerously high levels of lead has dropped since screening started, experts insist that lead poisoning remains a serious problem.

For one thing, they note, an estimated 30 million houses in the country still contain lead paint. They point to research showing that children with even low levels of lead in their blood can suffer behavioral problems and learning disabilities. And they say any disease that still affects 4 percent of children under 5--and 18 percent of black children that age in inner-city areas--is near epidemic proportions.

"I do not think there are many childhood diseases that approach that number," said Dr. Vernon Houk, who headed the government's lead screening program before it was folded into the block grant.

The critics are also concerned about the removal of Dr. Irwin Billick, a HUD researcher who demonstrated a direct correlation between lead poisoning and lead in gasoline. Ellen Silbergeld of the Environmental Defense Fund charged that Billick was fired in retaliation for his research. Considering that the administration wants to put lead back in gasoline, "that was not welcome news," Silbergeld said. HUD officials denied trying to punish Billick.

"The research is not what helps the people in the houses, it's the actual elimination of hazards," said E. S. Savas, assistant secretary for policy development and research. Although no money is earmarked specifically, Savas said, HUD is "seeking out lead paint hazards and eliminating those hazards" as part of "routine maintenance activities."

But the confluence of the cutbacks has critics concerned. "If the administration goes ahead and relaxes all these regulations . . . the effect is going to be to pump more lead into the environment, yet less money to find high-lead kids and treat them," said HHS adviser Lin-Fu. "The net effect is going to be disastrous."