Lead Levels Even Well Below U.S. Standard May Affect Brain Function In Ch...

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Lead Levels Even Well Below U.S. Standard May Affect Brain Function InChildren By Susan Lang. http://www.news.cornell.edu/stories/Nov07/lead.brain.damage.sl.html Even very small amounts of lead in children's blood -- amounts wellbelow the current federal standard -- are associated with reduced IQ scores,finds a new, six-year Cornell study. The study examined the effect of lead exposure on cognitive functionin children whose blood-lead levels (BLLs) were below the Centers forDisease Control and Prevention (CDC) standard of 10 micrograms per deciliter(mcg/dl) -- about 100 parts per billion. The researchers compared childrenwhose BLLs were between 0 and 5 mcg/dl with children in the 5-10 mcg/dlrange. "Even after taking into consideration family and environmental factorsknown to affect a child's cognitive performance, blood lead played asignificant role in predicting nonverbal IQ scores," said Richard Canfield,a senior researcher in Cornell's Division of Nutritional Sciences and seniorauthor of the study in the journal Environmental Health Perspectives. "Wefound that the average IQ scores of children with BLLs of only 5 to 10mcg/dl were about 5 points lower than the IQ scores of children with BLLsless than 5 mcg/dl. This indicates an adverse effect on children who have aBLL substantially below the CDC standard, suggesting the need for morestringent regulations," he said. In the United States over the last several months, nearly 50 specificproducts, including millions of toys for young children, have been recalleddue to excessive lead in the paint, plastics and metal. "Our findingsemphasize the very real dangers associated with low-level exposures, towhich lead in toys can contribute," Canfield said. U.S. children are exposed to lead primarily from household dustcontaminated by deteriorating interior lead-based paint. In addition totoys, other potential sources include contaminated soil, imported foodstored in lead-glazed pottery and certain plastic, metallic and paintedproducts. This most recent finding builds on the same research team'sinfluential 2003 study, published in the New England Journal of Medicine,that reported adverse effects of BLLs below 10 mcg/dl in a group of childrenfollowed from infancy to age 5. "Our new findings are based on follow-uptesting of the same children at age 6, using a more comprehensive IQ test toassess cognitive function. The results provide compelling evidence thatlow-level lead exposure has effects into the school-age years," said ToddJusko '01, a University of Washington Ph.D. candidate in epidemiology andco-author on both reports. "Children living in poverty disproportionately suffer from elevatedBLLs," said statistician and co-author Charles Henderson, a Cornell seniorresearcher in human development. He also noted that "even a small decline inan IQ score is likely to be reflected in aptitude test scores such as theSAT." According to the CDC, about one out of every 50 children in the UnitedStates between ages 1 and 5 has a BLL above 10 mcg/dl and about 10 percentof children have BLLs of 5 mcg/dl or higher; about 25 percent of U.S. homeswith children under age 6 have a lead-based paint hazard. "The bottom line," according to Canfield, "is that lead is apersistent neurotoxin that causes brain damage. The fact that lead has beenfound in millions of toys, even toys specifically designed for children toput into their mouths, presents an unacceptable risk. Our findings suggestthe need to re-evaluate the current federal standards for lead in consumerproducts and the current definition of an elevated BLL in children." The research was funded primarily by the National Institute ofEnvironmental Health Sciences.

 

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