WASHINGTON -- Citing "overwhelming" scientific evidence that even low levels of lead exposure can harm young children's development, the federal government has reduced its poisoning threshold for the toxic metal by 60 percent and called for increased screening and prevention efforts.
The move, announced here yesterday, vastly expands the number of children in Maryland and across the nation who are considered at risk of lead-related learning and behavioral problems.
It also renews the debate over who should shoulder the staggering financial burden of responding to what federal officials call the No. 1 environmental health threat to young children.
In guidelines issued yesterday, the federal Centers for Disease Control dropped its poisoning threshold of 25 micrograms of lead per deciliter of blood to 10 micrograms per deciliter. It also recommended various "levels of action" for doctors and health agencies, depending on the amount of lead found in a child's bloodstream.
The CDC urges that all children be tested for lead poisoning by age 2, but it adds that universal screening should be "phased in" over several years until cheaper and easier-to-use blood-sampling methods can be developed.
"These new guidelines are based on new data, which have shown that blood-lead levels which were previously believed to be safe are in fact associated with significant adverse effects," said Dr. Louis W. Sullivan, U.S. secretary of health and human services, at a Washington conference on lead poisoning.
Capable of causing brain damage, mental retardation and even death at high doses, lead exposure at levels as low as 10 micrograms per deciliter has been linked with IQ losses, developmental disabilities and other problems in toddlers and young children whose brains are still growing, studies have found.
There may even be harmful effects from lead levels below 10 micrograms per deciliter, the CDC report said, but there is insufficient evidence to be certain.
Federal officials estimated in 1984 that as many as 4 million American children -- or one in six -- had enough lead in their bloodstream to meet the new standards for intervention.
Lead is found practically everywhere -- in air, soil and water -- but the main exposure comes from deteriorating lead paint and dust in homes. Though lead-based house paint was banned in 1978, it remains in roughly 57 million homes, including nearly 4 million housing toddlers and young children who are most at risk from ingesting the metal.
In Maryland, 500,000 houses built before 1950 are believed to contain lead paint, with 200,000 of them in Baltimore. State health officials have estimated that half the young children in the Baltimore metropolitan area may have enough lead in their bloodstream to warrant some kind of intervention under the new guidelines.
Nearly 12,000 Maryland children, or about half of all those screened last year, had bloodstream lead levels above the new threshold, according to the Maryland Department of the Environment. Only 1,450 children were classified as poisoned under the old standard.
About 12 percent of Maryland's young children are screened for lead poisoning now, slightly better than the national average. But state officials predict that testing will soar in the wake of CDC recommendations. Local health departments' caseloads for dealing with poisoned children also could swell at a time when funding has been slashed 25 percent.
"This is hitting at a bad time," said Dr. Polly Harrison, director of child health for the Maryland Department of Health and Mental Hygiene.
"Given the resources we have now, we'll have to focus primarily on responding to [poisoned] children," said Amy Spanier, lead poisoning prevention coordinator for the Baltimore City Health Department.
The city and state have received a $300,000 CDC grant, which they plan to use to target screening and prevention efforts better.
Public health advocates, lawmakers and environmentalists praised the guidelines, but questioned the Bush administration's commitment to following through with funds and legislation.
The administration's "strategic plan" for dealing with lead poisoning, released last February, projected it would cost $1 billion for the next five years.
U.S. Rep. Henry A. Waxman, D-Calif., chairman of the House health and environment subcommittee, accused the administration of waffling, refusing to request enough money and opposing legislation that seeks to enact administration recommendations.
Congress already has doubled the administration's request for $25 million to help clean up lead-contaminated houses, and provided another $25 million to assess the hazards in public housing.
Sullivan said that he believes prospective home buyers should have a right to know whether their property contains lead, but that states, not the federal government, should be responsible for deciding whether to require inspection and disclosure when houses are sold.
Meanwhile, the Lead Industries Association issued a statement yesterday challenging the government's decision to lower the poisoning threshold.
The industry statement contended that "considerable controversy surrounds the effects of low-level exposure to lead." It called on the government to delay its action until there has been a "comprehensive impartial review" of the research.
But Sullivan rejected such criticism.
"The general public needs to be aware that the risks of lead exposure are not theoretical calculations," Sullivan said. "They are not extrapolated from data on laboratory animals. . . .
"They are the all too real consequences real children suffer from everyday lead hazards that are widespread in our environment."