By Kevin Drum
I know, I know: I’m a broken record on the subject of lead exposure in kids and crime rates 20 years later. But there’s lately been a renewed focus on black crime and black incarceration rates, as well as the racial profiling of blacks and Hispanics in New York City’s stop-and-frisk program. Guess what? The lead theory has something to say about that.
For starters, did you know that arrest rates for violent crime have fallen much faster among black juveniles than among white juveniles? They have, as the charts below show. Rick Nevin explains why:
African-American boys disproportionately involved in the criminal justice system were also disproportionately exposed to lead contaminated dust as young children, because black children were disproportionately concentrated in large cities and older housing. In 1976-1980, 15.3% of black children under the age of three had blood lead above 
30 mcg/dl (micrograms of lead per deciliter of blood), when just 2.5% of white children had blood lead that high. In 1988-1991, after the elimination of leaded gasoline, 1.4% of black children and 0.4% of white children under the age of three had blood lead above 25 mcg/dl.
In other words, black juvenile crime rates fell further than white juvenile crime rates because they had been artificially elevated by lead exposure at a much higher rate. In the early 80s, black kids had elevated lead levels at 6x the rate of white kids. After the elimination of leaded gasoline, black kids still had elevated lead levels at 3x the rate of white kids, which explains some of the continued disparity in juvenile crime rates, but that still represented enormous progress. Not only was the ratio lower, but the absolute numbers were far lower too.
