A hot topic recently on some of the research-oriented web forums I monitor has been an article published this month in Mother Jones. Author Kevin Drum posits a theory that the meteoric rise of violent crime in the United States in the 1970s and 1980s, as well as the precipitous fall in the 1990s and 2000s is the result of the effects of rising and falling levels of environmental lead.
Environmental lead, in turn, tracks the growing use of leaded gasoline in internal combustion engines, and the 1970s switchover to unleaded fuels. The bell-shaped curves of lead and crime look like mirror images, lagged by about 20 years. Could this indicate that a generation of children exposed to high levels of lead was more likely to produce individuals with violent propensities? And could the unexpected decline in violence in recent decades simply be the result of getting the lead out thirty years ago?
It is an intriguing thought, but as seasoned readers of my blog know, correlation does not necessarily mean causation. The author is a journalist, not a scientist, and Mother Jones isn't exactly a peer-reviewed professional journal. Nonetheless, the article was thought provoking, and might even stimulate more rigorous examination of the possible link.