More useful discussion of the (under-discussed) lead-crime-rate connections

A helpful reader alerted me to this helpful and lengthy new article at the Juvenile Justice Information Exchange headlined "Is Lead Exposure the Secret to the Rapid Rise and Fantastic Fall of the Juvenile Crime Rate?".  Here are excerpts from a piece worthy of a full read (and with lots of helpful links to the research discussed):

For the juvenile justice field, there is no larger question. It’s the elephant in the room, the great mystery, the trend that has changed everything — and seemingly without explanation. Why have juvenile crime rates, once predicted to rise inexorably, instead been falling for two decades? Falling... and falling... and falling.

What if the answer was readily available? What if it mostly boiled down to a single element, hiding in plain sight, and we just refused to notice? Well, compelling evidence suggests that much or most of the fluctuation in juvenile crime rates does boil down to a single element — a chemical element.

The element is lead, and a powerful body of research indicates that the recent declines in juvenile offending rates, like the rise in juvenile crime rates that preceded them, stem in large part from changes in children’s exposure to lead paint and exhaust from leaded gasoline. The idea may sound crazy, “like a bad science fiction plot,” quips Rick Nevin, one of the leading researchers documenting the link between lead exposure and crime. But the data don’t lie and here’s what they say.

For centuries it has been clear that lead is a potent poison. At extreme concentrations, lead poisoning causes anemia, blindness, renal failure, convulsions, abdominal spasms, insomnia, hallucinations, chronic fatigue and, ultimately, death. But only in the past four decades have researchers learned that lead exposure can severely damage the cognitive development of children, even at modest levels that produce no physical symptoms. And only through modern scanning technology have we learned that the lead molecule is perfectly designed to cripple young minds in ways that not only lower IQ, but also damage the very parts of the brain that oversee aggression, self-regulation, attention and impulse control.

As Kim Cecil, director of epidemiology and biostatistics at the University of Cincinnati College of Medicine, recently explained to the Chemical & Engineering News, “These are the parts of the brain that say, ‘Ooh, I’ve learned from before that I shouldn’t steal that, or if I do this, then the consequences are that.’” Even moderate levels of lead in the bloodstream of an infant or toddler significantly increase the odds that he will suffer behavioral disorders in childhood, and will engage in delinquency and criminal behavior later on. (Lead seems to affect boys more than girls.) A study published in 2008 tracked 250 children born in low-income Cincinnati neighborhoods between 1979 and 2004. It found that children with elevated levels of lead exposure (either in utero, or in early childhood) were significantly more likely to be arrested for both violent and nonviolent crimes than children with lower lead exposure. Earlier studies in Philadelphia and Pittsburgh also found a significant correlation between early childhood lead exposure and later conduct problems....

[T]he strength and consistency of the findings linking lead exposure and crime trends, plus the wealth of corroborating evidence from other disciplines (such as brain imaging studies and longitudinal studies of small population samples in selected cities) creates what Kevin Drum, a widely-cited blogger and journalist who has written extensively on the lead-crime connection, calls “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,” writes Drum. “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.”

By this point, readers of this column may be wondering: If the evidence linking lead exposure and crime is so strong, why haven’t we heard more about it? The primary reason is that the research has been largely ignored by academics. In 2008, a 250-page report on U.S. crime trends by the National Academies of Science included only one paragraph about lead exposure, drawing no conclusions. Late last year, a National Academies roundtable on crime trends did hold a session on lead exposure.

But even in that day’s session, the opening presentation — delivered by the renowned British criminologist, David Farrington — did not include a word about lead exposure. His talk on “Individual Differences in Antisocial Behavior, Delinquency, and Crime” discussed unemployment, parenting, poverty, family size, peer influences, substance abuse, and even an individual’s resting heart rate — none of which has seen changes in recent times consistent with the larger rise and fall in crime rates. Farrington said nothing about the introduction and subsequent removal of massive amounts of a toxic substance with a powerful known link to subsequent delinquency and criminality.

Drum suggests that the lack of attention to lead exposure is natural, given that the theory is new and unproven. Indeed, some critics have raised legitimate questions about the research — citing the small number of studies, questioning methodology and suggesting that other factors beyond lead (such as demographics, shifting drug markets and more) may also play an important role in determining crime rates over time....

Another factor behind the inattention to the lead exposure research is that most of the studies thus far have been conducted by economists and public health scholars, not criminologists, and the key papers have been published in environmental journals rather than criminology publications. Nevin also sees an element of self-interest: “Everyone has their own theory that they hold dear about why the crime decline has occurred,” he says. “There are a whole lot of people ... on both sides of the political spectrum who want to claim credit for this and don’t really like hearing about this unrelated powerful force.”...

[T]he lead data suggest that perhaps the most important thing our nation can do to reduce juvenile crime — and also to boost youth success in general — has nothing to do with juvenile courts or corrections systems. Maybe our first priority should be lead abatement — finishing the job by removing the last remnants of our tragic 20th century fetish with this terrible toxin.

 Some recent related posts:

• Should we thank unleaded gas and the EPA for the great modern crime decline?
• Effective Washington Post commentary talks up great (and still puzzling) crime decline
• Do lead exposure realities continue to best explain modern crime-rate realities?:
• Uh-oh: BJS reporting significant spike up in violent and property crime for 2012
• FBI releases 2012 crime statistics showing stability in relatively low crime rates
• New National Academy of Sciences effort seeking to unpack the crime decline