Mother Jones:

Jessica Wolpaw Reyes has a new paper out that investigates the link between childhood lead exposure—mostly via tailpipe emissions of leaded gasoline—and violent crime. Unsurprisingly, since her previous research has shown a strong link, she finds a strong link again. But she also finds something else: a strong link between lead and teen pregnancy.

This is not a brand-new finding. Rick Nevin’s very first paper about lead and crime was actually about both crime and teen pregnancy, and he found strong correlations for both at the national level. Reyes, however, goes a step further. It turns out that different states adopted unleaded gasoline at different rates, which allows Reyes to conduct a natural experiment. If lead exposure really does cause higher rates of teen pregnancy, then you’d expect states with the lowest levels of leaded gasoline to also have the lowest levels of teen pregnancy 15 years later. And guess what? They do. …

The neurological basis for the lead-crime theory suggests that childhood lead exposure affects parts of the brain that have to do with judgment, impulse control, and executive functions. This means that lead exposure is likely to be associated not just with violent crime, but with juvenile misbehavior, drug use, teen pregnancy, and other risky behaviors. And that turns out to be the case. Reyes finds correlations with behavioral problems starting at a young age; teen pregnancy; and violent crime rates among older children.