|
|
"Millions more children may suffer from lead exposure, study says..."Lead is a toxic metal that can interfere with development of the central nervous system and can be detected in blood and bones. Severe lead poisoning, which can cause seizures and even death, can sometimes be treated with medication, but Lanphear said the more subtle declines in mental functioning linked to lead are persistent and may be permanent. In a study of 417 youngsters in Allegheny County, Pa., significantly higher bone-lead levels were found in those convicted of delinquency than in a comparison group of young people with no juvenile convictions, reported Dr. Herbert Needleman of the University of Pittsburgh. Among boys, convicted juveniles were nearly twice as likely to have high bone-lead levels as the youngsters in the comparison group. The risk for girls was even higher, partly because only a small number of female delinquents -- 21 -- was studied, Needleman said. The findings suggest a possible link between early lead exposure and 11 percent to 37 percent of arrested delinquents, said Needleman, whose previous research linked aggressive and anti-social behavior to lead. Lead exposure may be one of the most preventable causes of criminal behavior, he said. Americans' blood lead levels have dropped significantly in the past 30 years with the removal of lead from gasoline, residential paint, plumbing systems and cans. But it remains a threat primarily in old paint, and children who eat paint chips or crawl on floors covered with old paint dust are especially at risk. The government's acceptable blood lead level is 10 micrograms per deciliter. An average of 4.4 percent of children ages 1 to 5 _ about 890,000 youngsters -- have levels at least that high, though in some poor communities with old housing the average levels are significantly higher, said Don Ryan, executive director of the Alliance to End Childhood Lead Poisoning, an advocacy group. But Lanphear found cognitive impairment, especially affecting reading ability, in children with levels as low as 2.5 micrograms per deciliter. Lanphear studied national data on 4,853 children ages 6 to 16 from 1988 through 1994, comparing blood lead levels and scores on tests of reading and math ability. Most had blood lead levels below 10. But for every increase of one microgram, there was an estimated reduction in reading scores of 1 point and a slightly smaller drop in math scores. The findings suggest that harmful effects are seen with the lowest detectable blood lead levels -- effects that at best could mean the difference between an A or B grade, Lanphear said. He estimated that more than 12.8 million U.S. youngsters born between 1972 and 1988 have blood lead levels in excess of 2.5 micrograms and "are adversely affected by environmental lead exposure." The recommended limit "is inadequate to protect children," said Lanphear, proposing a maximum threshold of at least half the current 10-microgram limit. Jeffrey Miller, executive director of Lead Industries Association, a trade group for battery makers, lead-scrap recyclers and other lead users, said it is difficult to prove a link between low blood-lead levels and cognitive problems. "These effects may not be significant," he said, noting that most adults today "had blood lead levels above 15 and 20 and 25 when they were young" without any notable harmful effects. "Rather than worrying about such minor effects," he said, the focus should be on "kids who truly do have lead poisoning." |