One of the things that Richard Nixon did that he doesn’t get credit for is getting lead out of paint and gasoline.

Kevin Drum has written a lot about how falling crime rates 20 years after environmental lead was removed from paint and gasoline crime fell, and now we see lead exposure correlates to teen pregnancy as well:

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 chart on the right shows the correlation between gasoline lead exposure and later rates of teen pregnancy, and it’s very strong. Stronger even than the correlation with violent crime.

It’s not surprising.

One of the effects of lead on the developing brain is reduced impulse control, and it seems obvious to me that lack of impulse control would increase the likelihood of high risk sexual behaviors.