A Reuters article reports that Lead is Linked to Adult Crime and Brain Damage
Those with high lead levels before birth and during early childhood had higher rates of arrest than those with lower lead levels. About 55 percent of the now-grown children had at least one arrest, 28 percent involving drugs and 27 percent serious motor vehicle violations.
I think this is a long shot.. I would like to know more about the arrest records of the control group. What is a serious motor vehicle violation? fatalities? injuries? parking tickets?