Studies show danger of even small amounts of lead in children’s blood

Levels well below the CDC ‘threshold’ are linked to kidney damage and other harmful effects.

By Tammy Worth, March 8, 2010 High doses of lead have for some time been linked to chronic kidney damage. But a recent study out of Johns Hopkins Children’s Center found that even small levels of lead exposure may be damaging to children’s kidneys. The report, published January in the Archives of Internal Medicine, looked at the records of 769 healthy youth ages 12 to 20 with average blood lead levels of 1.5 micrograms per deciliter (well below the 10 microgram “threshold” of concern per the Centers for Disease Control and Prevention). Researchers found that children with levels of just 2.9 micrograms per deciliters had worse kidney function than those with lower levels. With each doubling of lead levels, the filtration capacity dropped. It is just the latest study in a growing body of research finding that lead levels well below the CDC’s threshold may have a detrimental impact on children’s health. “I don’t think anyone thinks there is a safe level of lead,” said Dr. Jeffrey J. Fadrowski, a pediatric nephrologist at Hopkins Children’s Center and a coauthor of the kidney study. “But the question becomes where you can reasonably mount a public health response.” Though lead is no longer found in gasoline and paint, children and adults still incur exposure from items such as old paint, contaminated soil and drinking water. Approximately 1.4% of children had blood lead levels equal to or greater than 10 micrograms per deciliter in 2006 (the latest date for which nationally representative figures are available), down from 9% in 1988, according to research released in 2009 by the CDC. Lead exposure affects cognitive ability and behavior. Studies have shown that children with elevated blood lead levels have problems such as hyperactivity, attention dysfunction, aggression and lowered IQ. Lead can also harm the kidneys and reproduction and cause hypertension and gastrointestinal issues such as colic, nausea and constipation. The CDC’s threshold was reduced from 30 micrograms to 10 in 1991 in response to studies showing potential health effects at the lower levels. For children with levels higher than 10 micrograms, many states have intervention programs, according to the Agency for Toxic Substances and Disease Registry. Medical evaluation and environmental remediation is performed when children test higher than 20 micrograms. And medical treatment may be necessary when blood lead concentration is higher than 45 micrograms. But concern is growing among researchers and physicians about even lower levels. …