ATLANTA (AP) – Children with blood lead levels lower than the U.S. standard may still suffer lower IQs or other problems, a government advisory panel said Thursday as it urged doctors to be more alert to signs of lead poisoning.

The warning, in a report from the U.S. Centers for Disease Control and Prevention, comes amid growing parent concerns over imported toys with lead.

Lead poisoning can cause irreversible learning disabilities and behavioral problems and, at very high levels, seizures, coma and even death.

The CDC has never set a threshold for what defines lead poisoning. But it created a standard of sorts in 1991 when it said a lead level of 10 micrograms per deciliter of blood should prompt a doctor to assess the child’s environment and take other protective steps.

“You can have toxicity at levels all the way down to zero,” said Dr. Morri Markowitz, director of the pediatric environmental sciences clinic at New York City’s Montefiore Medical Center. He was not involved in the report.

However, the guideline of 10 micrograms has become the number that doctors use when deciding to refer a child for further attention. The same number is used in Canada and Britain.

This is the first time the Advisory Committee on Childhood Lead Poisoning Prevention has focused on the risks to children with lower levels of lead in their blood, said Dr. Helen Binns of Northwestern University, primary author of the report.

The panel isn’t proposing a new standard, she said, but is “emphasizing that all levels are important.”

The report is being published in the November issue of the medical journal Pediatrics.

Children with blood lead levels below 10, or even those up to 20, exhibit no obvious symptoms. But scientists believe intellectual development may be affected at lower levels.

The new report was driven by recent research that indicated differences in intellectual development of children with measurable levels of lead poisoning as compared to other kids.

The paper advises doctors how to talk to parents of children who have lower levels of lead and how to describe the risk, nutrition changes and safeguards to prevent any additional exposure, Binns said.

There’s no treatment proven effective at reducing these lead levels in children.

, said Mary Jean Brown, chief of the CDC’s lead poisoning prevention branch.

“We don’t have an intervention that will lower a blood lead level from 8 to 4,” she said.

The paper also recommends that doctors check the labs they use for testing blood, because some are more exact than others.

Approximately 310,000 U.S. children aged 1-5 years have blood lead levels greater than 10 micrograms of lead per deciliter of blood, according to CDC estimates. That’s fewer than 2 percent of children in that age bracket.

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