Lead Exposure Associated with Behavior Problems

04/30/2007

Lead exposure in children is known to reduce IQ scores, but its effect on children's behavior has been uncertain. A study co-authored by a Children's Hospital investigator found that at age 7, children with higher-than-normal blood-lead levels were more likely to have behavior problems, such as aggression and difficulties in school.

The behavior problems identified in this study, published in the March issue of Pediatrics, were only partly related to lead's effects in lowering IQ, suggesting that even children with higher IQs may suffer from psychological and behavioral problems related to lead exposure.

Jerilynn Radcliffe, Ph.D., Department of Psychology, and her co-authors evaluated data from 622 children enrolled in the NIH-sponsored Treatment of Lead-Exposed Children Trial. The children were first studied between ages 12 to 33 months, then periodically followed up, and given neuropsychological and behavioral tests at ages 5 and 7. The investigators measured direct effects of blood-lead levels on behavior while adjusting for IQ.

It was previously thought that adverse health effects from lead exposure were transient and decreased after the toddler years. Blood lead levels generally peak at age 2, but lower concentrations at school age may also be important because there is no safe threshold level at which lead does not have effects. This study suggests that health effects persist in school-age children.

The results may also point to a need to screen schoolchildren for elevated blood-lead levels and underscore the importance of preventing lead exposure. Measures such as cleaning residues of lead dust from old house paint should start in a child's earliest years and continue into school age.