Kevin Drum connects lead exposure to crime rate racial discrepancies:
Both gasoline lead and lead paint were most prevalent in the postwar era in the inner core of big cities, the former because that’s where cars were densest and the latter because slumlords had little incentive to clean up old buildings. Because African-Americans were disproportionately represented in inner-city populations during the high-lead era, they were disproportionately exposed to lead as children. The result was higher rates of violent crime when black kids grew up in the 70s and 80s.
More of the Drum-lead thread here.