The linked articles give compelling evidence for the case that leaded gasoline caused the huge spike in violent crime starting in the ’60s, as well as the equally sharp decline starting in the ’90s. From the cover story:
“All of these studies tell the same story: Gasoline lead is responsible for a good share of the rise and fall of violent crime over the past half century.”
“Everyone over the age of 40 was probably exposed to too much lead during childhood, and most of us suffered nothing more than a few points of IQ loss. But there were plenty of kids already on the margin, and millions of those kids were pushed over the edge from being merely slow or disruptive to becoming part of a nationwide epidemic of violent crime.”
Thanks to Josh for these links.