Air Date: Week of February 16, 1996
Steve Curwood speaks with Dr. Herbert Needleman, author of a scientific study linking criminal aggression to lead levels in children's blood. Dr. Needleman is a professor of psychiary and pediatrics at the University of Pittsburgh Medical school.
CURWOOD: This is Living on Earth. I'm Steve Curwood. A provocative new study suggests that the epidemic of crime in America today could be partly due to the widespread exposure of children to lead. For years it has been known that children recovering from acute lead poisoning tend to be more aggressive and have behavioral problems. But what about children exposed to small amounts of lead, who don't have any physical symptoms? Landmark research done by Dr. Herbert Needleman years ago demonstrated that even tiny amounts of lead exposures for kids could lead to lowered intelligence, learning disabilities, and higher school dropout rates. Dr. Needleman's research led the Federal Government to lower the threshold of lead poisoning it considers dangerous. As many as 1 in 12 young children in America today have these dangerous but asymptomatic levels of lead in their blood, and the number is much higher among the poor, urban, and black. Now, Dr. Needleman has studied the effects of low levels of lead in relation to aggression and delinquency, and published the results in the Journal of the American Medical Association. He found that even when race, poverty, and family stability are taken into account, low levels of lead significantly increase attention problems, aggression, and delinquency. I asked Dr. Needleman why he decided to study these links.
NEEDLEMAN: Anybody who's treated kids with lead poisoning, and I've done a considerable number of them, will hear parents say that their child was a very nice kid, very easy to manage, and then got lead poisoning and then became unmanageable. That's not an uncommon story. So I decided to see if using more sensitive measures, that effect persisted at lower doses.
CURWOOD: And so what did you find?
NEEDLEMAN: Well, we studied something over 200 boys in the Pittsburgh school system. We measured the lead in their bones by a relatively new technique, X-ray fluorescence. We had questionnaire data, good questionnaire data, on their behavior from their mothers, from their teachers, and from the subjects themselves, and we found out the children with the higher lead levels had a significantly higher rate of attention problems, aggressive behavior, and delinquent behavior.
CURWOOD: How much greater rate?
NEEDLEMAN: It was almost twice as frequent.
CURWOOD: Why do you suppose that even tiny amounts of lead make kids act out more, become more aggressive?
NEEDLEMAN: Well, it's a brain poison, and the brain mediates impulses, that's one of the important functions of the brain is to make you think of the consequences of an act before you commit it. And I believe that lead interferes with that capacity of the brain to say to a child, if I throw this brick at this person something bad might happen.
CURWOOD: Now, does your study mean that kids who are exposed to lead are more at risk of becoming juvenile delinquents?
NEEDLEMAN: Yes, exactly. I do not think that every child with an elevated blood lead is going to be delinquent, but I think it does raise the risk of delinquency.
CURWOOD: Dr. Needleman, how big a factor do you think lead is in terms of crime and delinquency and violence in our society?
NEEDLEMAN: I haven't made that estimate. I'm going to try to. Criminality can be predicted early, that's true. It's more common in boys, that's true. It's more common in African Americans, that's true. It's more common in urban dwellers. Criminals have lower IQ scores, and more hyperactivity. All of these are also shared by lead. Now I'm not saying that lead is the cause of criminality, of course I'm not saying that, but I think it may be a substantial cause. If it's somewhere between 5 and 20%, that's an enormous amount of preventable disease.
CURWOOD: Dr. Needleman, what are the implications for a society if kids that are exposed to small amounts of lead, so small that they don't have symptoms, that they have twice the delinquency rate or twice the aggressive tendencies as kids that aren't exposed?
NEEDLEMAN: If lead is a contributor to the variance that leads to delinquency, it's a completely preventable contributor. And I think this is increased incentive to remove lead from old housing stock before it gets into children, rather than removing it from children once it gets into their body. I think that this offers a splendid opportunity to perhaps reduce one of our most important societal problems.
CURWOOD: Dr. Herbert Needleman is a professor of psychiatry and pediatrics at the University of Pittsburgh Medical School.
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