Lead, the criminal element

I've heard before about the postulated link between atmospheric lead levels (courtesy of the leaded gasoline used through the middle decades of the 20th century) and crime levels.  This Mother Jones article America's Real Criminal Element: Lead is the best explanation I've seen so far (and has links to the original papers).  It really sounds like this hypothesis is fully confirmed - and the best thing about this story is that it has a happy ending.  (Unless you're trying to get elected as mayor - or Prime Minister - on a tough-on-crime platform).

There is a nice geospatial connection here.  As with many epidemiological issues, spatial locality is an important aspect of the analyses that lead (ahem) to the conclusion.  The article is chock-full of references to the spatial nature of the problem, such as:

We now have studies at the international level, the national level, the state level, the city level, and even the individual level

and my favourite:

a good rule of thumb for categorizing epidemics: If it spreads along lines of communication, he says, the cause is information. Think Bieber Fever. If it travels along major transportation routes, the cause is microbial. Think influenza. If it spreads out like a fan, the cause is an insect. Think malaria. But if it's everywhere, all at once—as both the rise of crime in the '60s and '70s and the fall of crime in the '90s seemed to be—the cause is a molecule.