Worth reading: A recent Mother Jones article entitled, "America's Real Criminal Element: Lead." Despite the awful pun in the title, the article is engrossing. It's a look at one of a field of competing theories for the source of a curious and widespread drop in violent crime in the U.S. beginning in the 1990s. Law enforcement tactics, especially broken windows policing, which focuses on combatting petty crimes to prevent an atmosphere of tolerance that allows larger crimes to gain a foothold, have long been credited for cleaning up New York. But studies carried out by researchers working independently have found a curious correlation between the decline in major crimes in New York and (interestingly) other cities and the decline in the amount of lead in the atmosphere in said cities.
With the rise of the car, but prior to the rise of the catalytic converter (which removes lead and other impurities from gasoline emissions) and the EPA's unleaded gas standards, cars all over the road were burning leaded gas and pumping it into the atmosphere and ultimately to settle into the soil. It's here that kids come in, being exposed to the lead and all and suffering a demonstrable loss of IQ points as a result. In the eyes of some researchers, these kids grew up to be dumb, short-tempered criminals accounting for the high major crime rates. And after the introduction of unleaded gas, the crime rates fell at about the same rate as it took them to rise following the rise of leaded gas. Pretty interesting.