Exposure to lead in the environment may contribute significantly to criminal behavior, a possibility that might help explain the high rates of crime in America’s inner cities, researchers said Tuesday.
A study released today suggests that even nominal doses of lead, well below those associated with poisoning, can lead to anti-social behavior and delinquency in young boys - behavior that foreshadows violent adult criminality.
The study, published in the Journal of the American Medical Association, extends a landmark 1990 study, which demonstrated that lead poisoning in childhood is the single most important predictor of criminality among adults. It far outweighed poverty, the absence of a father and other major social factors.
Dr. Herbert L. Needleman and his colleagues at the University of Pittsburgh School of Medicine studied 301 boys from the Pittsburgh inner city. They found that boys with above-normal lead values were more aggressive and had higher delinquency scores when evaluated by teachers, parents and, most important, their own self-reports.
These delinquent behaviors, which include bullying, vandalism, setting fires, theft and fighting, are highly predictive of adult criminality, alcoholism and domestic abuse, said psychologist Terrie E. Moffitt of the University of Wisconsin.
“We’re not saying that lead is the cause of all the rotten decay in our cities, but it is not unreasonable that it is a part of the picture, perhaps a measurable part,” Needleman said.
“This is extremely important for crime and violence research,” added criminologist Deborah W. Denno of Fordham University.
The most important sources are lead in soil - deposited over decades by automobiles burning gasoline containing tetraethyllead as an octane enhancer - and in houses built before 1978. Paint in such houses often contains as much as 50 percent lead and, even though it has been covered by lead-free paints, it still flakes off when doors and windows are opened and closed and furniture rubs against walls. Studies have found that the old houses and contaminated soils of inner cities are by far the highest sources of lead.
The effects of lead were independent of race, Needleman found.
The results suggest that the relatively high incidence of crime in some black communities does not result from a racial predisposition, as some have suggested, but from a phenomenon increasingly known as “environmental racism,” Denno said.
Environmental racism, she said, reflects the fact that pollutants, such as lead, tend to be dumped or accumulate in areas where blacks and other minorities reside.