Researchers tested the lead bone concentrations of 194 youths aged 12 to 18 convicted in the Allegheny County Juvenile Court in Pennsylvania and 146 students in regular high schools in Pittsburgh who did not have behavioral problems.

The study found delinquent children were four times as likely to have elevated concentrations of lead in their bones. The mean concentration of lead in the convicted youths was 11.0 parts per million, compared to only 1.5 parts per million among other high schoolers. Based on their findings, researchers attribute an estimated 11 percent to 38 percent of juvenile delinquency in Allegheny County to lead exposure.

"This study suggests a substantial proportion of delinquent behavior is due to a preventable cause -- lead," says Dr. Herbert Needleman, lead author of the study and a University of Pittsburgh professor of child psychiatry and pediatrics. "Very small amounts of lead are associated with toxicity."

The study appears in today's issue of Neurotoxicity and Teratology.

Ross has more on this.