Childhood exposure to high lead levels leads to smaller brain mass and is linked to criminal behavior and violence, according to two new comprehensive studies. Researchers tracked kids from Cincinnati, Ohio, from before birth through adulthood and found that early exposure to lead resulted in a loss of brain matter of over 1 percent on average, particularly in the areas of the brain responsible for controlling impulses, regulating emotions, and anticipating consequences. Higher blood lead levels were also found to be strongly correlated with more arrests in adulthood, especially for violent behavior. Lead poisoning has long been associated with lower IQs and behavioral problems, but the two new studies are the first to follow lead-exposed kids from birth to adulthood and establish a direct link between lead poisoning, brain size, and higher arrest rates. “Although we’ve made great strides in reducing lead exposure, our findings send a clear message that further reduction of childhood lead exposure may be an important and achievable way to reduce violent crime,” said Kim Dietrich of the University of Cincinnati.