Declaring there is an unequivocal link between lead in gasoline and lead poisoning of children, a top federal health official said yesterday there is no scientific justification for an Environmental Protection Agency proposal to relax or rescind restrictions on lead in gasoline.

Dr. Vernon N. Houk, acting director of the Center for Environmental Health of the Center for Disease Control, said that studies "clearly demonstrate that as we have removed lead from gasoline, we have also removed lead from ourselves and our children."

Testifying before a House subcommittee on a panel with two private physicians and Dr. Phillip Landrigan, of the National Institute of Occupational Safety and Health, Houk urged continued lead reductions and, on questioning, added, "I am not aware of any medical evidence that would support an end to the EPA phase-down" of lead in gasoline. The other panel members, all experts in lead poisoning, agreed.

Meanwhile, in a recent letter to EPA, Asamera Oil Inc. of Denver complained that agency actions and proposals penalize those companies which met the standards, while "those companies that seem to exist on the fringes of the industry are enjoying very significant product cost advantages over Asamera and others."

In February, the EPA, at the urging of the Presidential Task Force on Regulatory Reform, issued a proposal to relax or rescind 1973 regulations requiring refineries to reduce the level of lead in gasoline. Lead is added to gasoline as a cheap antiknock additive, and this form accounts for about 90 percent of all airborne lead.

EPA is scheduled to hold hearings today and Friday on the proposal. The congressional hearings were intended to spotlight EPA activities and medical opposition.

Rep. Toby Moffett (D-Conn.), who chaired the hearings, charged that EPA has already decided to weaken the regulations before hearing from opponents. He cited comments reportedly made in December by EPA administrator Anne Gorsuch to officials of a New Mexico refinery, indicating EPA would not enforce the lead standards because it planned to weaken them.

Following that meeting, Gorsuch allegedly told an aide to Sen. Harrison Schmidt (R-N.M.) that she couldn't come right out and advise the firm to violate the standards, but she hoped they got the message, according to the Schmidt aide. Gorsuch has denied making either comment.

Richard D. Wilson, acting director of EPA's Office of Air, Noise and Radiation Enforcement, told the subcommittee that Gorsuch has made no decision on the lead standands. But he disagreed with critics' claims that dropping the standards would necessarily cause airborne lead to increase.

Lead can result in attention and emotional disorders and learning disabilities. Symptoms include headaches, bellyaches and clumsiness.

Other sources of lead include lead-based paint and emissions from lead-related industries. But the major source is gasoline. Houk noted that in homes on congested streets, soil lead contamination in the front yards is normally two to three times greater than in the back yards. Lead poisoning hits 18.6 percent of urban black children, 4.5 percent of urban white children, and 2.1 percent of rural children.