I’ve been aware of the pretty amazing link between lead and crime for a while, but Kevin Drum really puts all the evidence together in a masterful piece for the latest Mother Jones. Quite simply, when you look at the huge increase in crime peaking in the early 90’s followed by the dramatic decline for the past two decades, far and away the single best explanation is environmental lead (largely from leaded gasoline). As Drum is at pains to point out, obviously this cannot explain everything, but compared to all other rival hypotheses, the myriad evidence for the role of lead is really compelling and downright overwhelming. First, a chart (crime rate is 23 years after lead as the effect is on developing brains and making them more prone to crime):
But that’s just a chart. Most importantly, everywhere you look for evidence, there it is:
Put all this together and you have an astonishing body of evidence. We now have studies at the international level, the national level, the state level, the city level, and even the individual level. Groups of children have been followed from the womb to adulthood, and higher childhood blood lead levels are consistently associated with higher adult arrest rates for violent crimes. 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. [emphasis mine]
And, there’s this, too:
The gasoline lead story has another virtue too: It’s the only hypothesis that persuasively explains both the rise of crime in the ’60s and ’70s and its fall beginning in the ’90s. Two other theories—the baby boom demographic bulge and the drug explosion of the ’60s—at least have the potential to explain both, but neither one fully fits the known data. Only gasoline lead, with its dramatic rise and fall following World War II, can explain the equally dramatic rise and fall in violent crime.
And, how is lead doing this. By wreaking havoc on developing brains:
But we now know that lead’s effects go far beyond just IQ. Not only does lead promote apoptosis, or cell death, in the brain, but the element is also chemically similar to calcium. When it settles in cerebral tissue, it prevents calcium ions from doing their job, something that causes physical damage to the developing brain that persists into adulthood…
So lead is a double whammy: It impairs specific parts of the brain responsible for executive functions and it impairs the communication channels between these parts of the brain. For children like the ones in the Cincinnati study, who were mostly inner-city kids with plenty of strikes against them already, lead exposure was, in Cecil’s words, an “additional kick in the gut.” And one more thing: Although both sexes are affected by lead, the neurological impact turns out to be greater among boys than girls…
In other words, as Reyes summarized the evidence in her paper, even moderately high levels of lead exposure are associated with aggressivity, impulsivity, ADHD, and lower IQ. And right there, you’ve practically defined the profile of a violent young offender. [emphasis mine]
Really, pretty amazing too contemplate all this. It’s also amazing (and distressing) that despite the wealth of strong, peer-reviewed evidence, this just had not made it through to the Criminology crowd who have completely ignored this important research.
Finally, Drum also makes the point that there’s still a lot of environmental lead that we can do something about. And when you consider the cost of turning people towards crime and less productive citizens, the benefit of this abatement hugely overwhelms the financial costs of doing so. We’re talking about a $10 to $1 return on investment. If only our policy-makers were smart enough and long-term oriented enough to actually address the issue. Argh.
Anyway, great piece. And consider all the ground he covers, quite concise. Really should read the whole thing. I loved it so much, I put it right into my syllabus which I finished off yesterday.