That said, I can't think of an easier problem for evolution to solve than this. I'm sure we'll get kids immune to plastic in a few more generations.
No, that's just a theory about why violent crime has gone down. No one really knows for sure. Someone noticed that crime rates have gone down, and that this correlates with reduced usage of leaded gasoline in North America.
Remember also that global warming has been going up over the past few centuries, and this has an inverse correlation with the number of pirates on the high seas. Back in the days of Blackbeard, we didn't have problems with global warming. Does this mean that greatly reducing piracy has caused global warming? Of course not. Correlation does not prove causation.
The banning of leaded gasoline might in fact have caused a reduction in violent crime, but it's not proven at this point.
…and the rest of the world… and it always happens after lead regulation… and there's a reasonable mechanism… did you read the article?
> Correlation does not prove causation.
This is a "middle-brow dismissal".
Anyway, here's an RCT on lead reduction in children: https://www.aeaweb.org/articles?id=10.1257/app.20160056