|Vol. 2, No. 2 , 1996, Page 1|
Last year, Crime Times reported on the strong link between lead exposure and behavior problems in children (See Crime Times, Vol. 1, No. 3, Page 4). This February, researchers reported important new evidence that high lead levels contribute to the aberrant behaviors most strongly associated with crime and delinquency.
The new study, published in the Journal of the American Medical Association by Crime Times Advisory Board member Herbert Needleman and colleagues, followed 212 boys in the Pittsburgh public schools from age 7 through age 11. None of the children had any overt signs of lead toxicity. The researchers calculated the boys' bone lead concentrations using a technique called K x-ray fluorescence, which measures cumulative exposure to lead.
During the four-year study, teachers and parents periodically filled out questionnaires evaluating the children for aggression, delinquency, and other behavioral problems. In addition, the boys themselves were asked to report whether or not they had engaged in antisocial behavior.
Only a slight association between lead levels and behavior was seen at age 7. But at age 11, the researchers report, the children with elevated lead levels were judged by both parents and teachers "to be more aggressive, have higher delinquent scores, and have more somatic complaints than their low-lead counterparts," and "the subjects themselves reported lead-related increases in antisocial acts." Other problems associated with high lead levels included anxiety, depression, social problems, attention deficits, and somatic complaints. Needleman and colleagues say their findings agree with clinical observations linking lead poisoning to disturbed behavior, and "extend the relationship downward in dose to asymptomatic youths with elevated body burdens."
The researchers say their findings held true even when they controlled for nine different measures of maternal intelligence, socioeconomic status, and quality of child rearing. "It is possible, of course, that some unmeasured socioeconomic factor is influencing outcome and is associated with lead," they say, "[but] it is unlikely that such a factor would not be correlated with any of the nine socioeconomic variates for which we controlled."
Needleman et al. conclude that "lead exposure is associated with increased risk for antisocial and delinquent behavior, and the effect follows a developmental course." They add that "if [our] findings are found to extend to the population of US children, the contribution of lead to delinquent behavior would be substantial."
Needleman's study was praised as "ground-breaking" by lead expert Kim Dietrich, professor of environmental health at the University of Cincinnati, who says that it is "the first rigorous study to demonstrate a significant association between lead and antisocial behavior." And lead researcher David Bellinger of Boston Children's Hospital, while cautioning that "criminality and violence [are] a final pathway for many different processes," comments that the study "opens the possibility that some of the violence in our society could be the result of preventable environmental pollution."
"Bone lead levels and delinquent behavior," Herbert Needleman, Julie Riess, Michael Tobin, Gretchen Biesecker, and Joel Greenhouse, Journal of the American Medical Association, Vol. 275, No. 5, Feb. 7, 1996. Address: Herbert Needleman, University of Pittsburgh Medical Center, Suite 305, Iroquois Building, 3600 Forbes Ave., Pittsburgh, PA 15213.