Lead Linked to Attention Deficit Hyperactivity Disorder

Photo: Maartje van Caspel / Istock

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Even minute levels of lead in the blood – lower than levels previously believed to cause no harm – have been linked to attention deficit hyperactivity disorder, or ADHD.

The research, by Michigan State University, involved only a small sample of children, 150. All children had levels of lead in their blood, but all at levels below the 10 micrograms per deciliter level that is currently considered safe by the Centers for Disease Control and Prevention. However, those with ADHD had higher levels of lead in their blood. The findings will be published Feb. 15 in Biological Psychiatry.

Joel Nigg, the psychologist who directed the study, said the neurotoxic effects of lead in the blood can interfere with stages of brain growth, such as synapse formation – a critical element in the development of appropriate self-regulatory control. Children age 2 and younger are particularly vulnerable, he said.

The findings are concerning, particularly in light of the rash of toys and other children's products that have been recalled this year due to the presence of lead paint. Other effects of lead, including lowered IQ and other permanent brain damage, at higher levels of exposure, have been well documented.

Lead paint in old homes is still believed to be the greatest source of lead exposure for children, and no studies have looked yet at how or whether toys have been a significant source of exposure. Two more children's products were recalled by the Consumer Product Safety Commission and their manufacturers last night: a potty training seat and holiday figurines.

“No one can completely eliminate all dust and lead from those houses,” Nigg said. “If you’re a parent of an infant or toddler in an older home who is worried about this, your best advice is to become scrupulous about sweeping up dust and dirt, filter tap water, remove chipped paint and monitor what your children put in their mouths.”

Nigg is continuing his research in the Lansing, Michigan area, and he is seeking the parents of children age 8-16, whether or not they have an ADHD diagnosis. To volunteer, call 517-432-4894.

For information about the latest recalls, see page 2 of this article.

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