And it's almost certainly bullshit. There is no correlation with crime rates and lead exposure. The pattern observed is a massive spike in crime during the '80s and '90s due to gang activity from the crack boom, which then falls back down to '60s/'70s levels afterward. What you'd expect to see if lead exposure was the problem is a very gradual increase over time and then a gradual tail off as exposure reduced. Instead the homicide rate doubled for folks under 25 between 1983 and 1993, and then fell back to 1980s levels by the early 2000s.
The background crime rate increase from the 1960s forward is more readily explained by societal changes, as well as the start of the "war on drugs".
