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LEAD EXPOSURE LINKED TO DELINQUENT BEHAVIOR
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."
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"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.
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