Lead Shrinks Brains, Causes Violence: Studies

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If children are exposed to lead, in the womb or in early childhood, their brains are likely to be smaller, and they are more likely to become criminals, according to two new studies published in PLoS Medicine.

There have been studies in the past associating lead exposure to behavioral problems, including violent crime. Some have even suggested that society-wide drops in crime rates can be attributed in part to the removal of lead from gasoline and paint in the 1970s.

The new study, by Dr. Kim Dietrich and colleagues at the University of Cincinnati, is more specific, because for the first time blood-lead levels in children were measured, and those children's lives were followed for years to see what effect early exposure might have. Other factors that might explain violent behavior, like mother's IQ, socioeconomic status and education level, were ruled out, showing a clear correlation between lead exposure and criminal behavior.

The second study, by Dr. Kim M. Cecil and colleagues at Cincinnati Children's Hospital Medical Center, might explain why, biologically. It followed hundreds of people and found that adults who had been exposed to lead early in life had about 1.2% less gray matter than those who had not been exposed to lead. Men were most susceptible, with losses of 1.7%.

Studies had already showed lead exposure caused a loss of IQ. The new studies show that the loss of brain matter was concentrated in an area of the brain that controls behavior – "critical 'executive' functions, such as impulse control, emotional regulation, judgment and the anticipation of consequences," as the Baltimore Sun put it.

Two more good reasons to keep lead-tainted toys out of the hands of children, to take care during maintenance and renovation of older homes that might still have lead paint, and to get your child's blood tested for lead frequently so any exposure can be identified and removed.

See our Tips for Preventing Lead Poisoning.

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