"When environmental lead finds its way into the developing brain, it disturbs neural mechanisms responsible for regulation of impulse. That can lead to antisocial and criminal behavior," reported Herbert L. Needleman, M.D., professor of psychiatry and pediatrics at the University of Pittsburgh School of Medicine, at the 2005 American Association for the Advancement of Science (AAAS) Annual Meeting. "The government needs to do more to eliminate sources of lead in the environment."
According to the U.S. Environmental Protection Agency, humans can encounter lead through deteriorating paint and dust, air, drinking water, food and contaminated soil. Sources of lead are plentiful - until the 1970s lead was used in paint, gasoline and older water pipes. Today, much of that lead is still out there - on old window frames, in the soil of the vegetable gardens and in the drinking water of many American cities.
In the 1970s, Dr. Needleman was the first to discover cognitive effects in children who had been exposed to lead. Though the children had no visible signs of lead poisoning, they had significantly lower scores on IQ tests. As a result of these studies and others, lead has been removed from gasoline, paint and numerous other products.
Such measures have resulted in sharply lower levels of lead in children born today, compared to those born 30 years ago. Yet, Dr. Needleman's latest research shows that even very low levels of lead found in bone, as measured by a technique called X-ray fluorescence, can affect brain development.
In a 1996 Pitt study of 301 children, those with the highest concentrations of lead - still below government-recommended safe levels - had tests scores showing more aggression, attentional disorders and delinquency. In 2002, those findings were extended to show that the average bone lead levels in 190 adjudicated delinquents was higher than normal controls. The results indicated that between 18 and 38 percent of all delinquency in Pennsylvania's Allegheny County, which includes Pittsburgh, could be due to lead. Additionally, a number of recent studies have shown a strong relationship between sales of leaded gasoline and rates of violent crime.
"The brain, particularly the frontal lobes, are important in the regulation of behavior," said Dr. Needleman. "Exposure to lead, at doses below those which bring children to medical attention, is associated with increased aggression, disturbed attention and delinquency. A meaningful strategy to reduce crime is to eliminate lead from the environment of children."
NOTE TO EDITORS: Dr. Needleman will discuss his research at a special AAAS session, "Shaping the Future: Environmental Pollution, Population Change and Economic Productivity, from 1:45 to 3:15 p.m., Friday, Feb. 18.