Rick Nevin: Race, Lead, and Juvenile Crime:
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… 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. There have been, and still are, lots of potential explanations for the disparity in violent crime rates… toxic legacy of racism and slavery; poverty rates in inner cities; gang culture… many more. But… none of the popular theories explains the dramatic rise and fall of crime over the past 50 years, nor in particular why black crime declined more than white crime starting in the early 90s