WASHINGTON -- Americans' exposure to lead has declined greatly in the past 15 years, but the toxic metal remains a major health threat for nearly 2 million young children, particularly inner-city black youngsters in cities like Baltimore, federal health officials reported today.
A nationwide federal health survey summarized in this week's Journal of the American Medical Association reports that levels of lead in the blood of children and adults dropped by 78 percent from 1976 to 1991.
Hailing it as a "remarkable public health achievement," officials for the federal Centers for Disease Control and Prevention attributed declining lead exposures to the government's removal of the metal from gasoline, water and consumer products, including food cans and house paint.
But in a statement accompanying the survey reports in JAMA, Environmental Protection Agency officials said the evidence of lingering lead poisoning among inner-city, poor and minority children means that society must intensify efforts to eliminate or reduce the hazard from lead-based paint that remains in millions of older homes.
"We still have a long way to go," Joseph Carra, the EPA's deputy director of pollution prevention and toxics, said in an interview.
"I think it puts pressure on us to keep [up] maintenance of old housing," said Dr. J. Julian Chisolm, director of lead treatment and prevention at the Kennedy Krieger Institute in Baltimore and a nationally recognized expert on the problem.
Lead poisoning often displays no symptoms, experts say, but swallowing even tiny amounts of lead can cause intelligence loss, learning disabilities and behavioral problems for children younger than 6, whose nervous systems are still developing.
The Centers for Disease Control declared in 1991 that there was sufficient research showing that young children begin to suffer harm from lead at levels as low as 10 micrograms per deciliter of blood. The agency urged universal screening of all children for lead poisoning and recommended that doctors follow up with any child found to have blood-lead levels of at least 15 micrograms per deciliter.
Based on examinations of more than 13,000 adults and childrenfrom 1988 through 1991, federal health officials estimated that 1.7 million children, or nearly one of every 11 children from 1 to 5 years old, still has harmful levels of lead in the blood. That is down sharply from estimates made in 1976 after a similar survey indicated that nearly 90 percent of such youngsters had elevated lead levels.
Lead levels among children have declined 75 percent since the 1970s, from a mean of 14.9 micrograms per deciliter to 3.6 micrograms in the latest survey.
The Lead Industries Association, which is fighting environmentalists' proposals to tax or ban continued uses of lead in car batteries, electronics and other products, hailed the federal survey.
But federal health officials noted that while lead exposures have dropped overall, they remain significantly higher on average for children in urban areas, particularly in the Northeast.
Nearly 37 percent of black children living in cities with at least 1 million residents had potentially harmful lead levels, health officials reported, which is more than seven times the rate found among white children in suburban and rural areas. The survey also found higher lead levels among Mexican-American children living in large cities.
In Maryland, about 28 percent of children up to 6 years old whoseblood was tested last year had potentially harmful lead levels, according to the Maryland Department of the Environment. Thirty-nine percent of tested Baltimore City children that age had elevated lead levels.
"The problem of childhood lead poisoning is just as real as it has been," said Donald Ryan, director of the Alliance to End Childhood Lead Poisoning, an advocacy group. The group released a public opinion survey it commissioned showing that most Americans support continued efforts to eliminate or reduce lead hazards.
With the new survey showing an uneven distribution of lead poisoning, EPA officials suggested that universal screening of children should be dropped in favor of targeting urban, poor and minority populations.
The CDC plans to drop universal screening recommendations for communities where initial tests find little evidence of a problem, said Dr. Sue Binder, the agency's chief of lead poisoning prevention.
But Dr. Ellen Silbergeld, a toxicologist and lead researcher with the University of Maryland, said that screening should be stepped up because it is far from universal even in problem areas like Baltimore. Only about 40 percent of city children were screened in 1992, she noted.
The primary sources of lead exposure today are from lead-based paint in older housing, from dust in soil and from drinking water, health officials say.
EPA regulations require testing and treatment of public water sources to reduce lead levels, and the agency recently issued guidelines for reducing lead hazards in dirt and soil.
Dealing with lead in housing has been much tougher, because nearly all homes built before 1950 and at least some of those built until 1978 contain lead-based paint. Almost 4 million homes nationwide have peeling and flaking lead-based paint, and about 500,000 homes in Maryland built before 1950 may contain lead BTC paint.
Maryland enacted state legislation this year requiring inspection and treatment of lead paint in rental homes built before 1950. In 1992, Congress passed a law that will go into effect next year that will require lead inspections of properties at the time of the sale and disclosure of information about the presence of lead in homes built before 1978.