America’s Real Criminal Element: Lead

January 5th, 2013

Via: Mother Jones:

In 1994, Rick Nevin was a consultant working for the US Department of Housing and Urban Development on the costs and benefits of removing lead paint from old houses. This has been a topic of intense study because of the growing body of research linking lead exposure in small children with a whole raft of complications later in life, including lower IQ, hyperactivity, behavioral problems, and learning disabilities.

But as Nevin was working on that assignment, his client suggested they might be missing something. A recent study had suggested a link between childhood lead exposure and juvenile delinquency later on. Maybe reducing lead exposure had an effect on violent crime too?

That tip took Nevin in a different direction. The biggest source of lead in the postwar era, it turns out, wasn’t paint. It was leaded gasoline. And if you chart the rise and fall of atmospheric lead caused by the rise and fall of leaded gasoline consumption, you get a pretty simple upside-down U: Lead emissions from tailpipes rose steadily from the early ’40s through the early ’70s, nearly quadrupling over that period. Then, as unleaded gasoline began to replace leaded gasoline, emissions plummeted.

ntriguingly, violent crime rates followed the same upside-down U pattern. The only thing different was the time period: Crime rates rose dramatically in the ’60s through the ’80s, and then began dropping steadily starting in the early ’90s. The two curves looked eerily identical, but were offset by about 20 years.

So Nevin dove in further, digging up detailed data on lead emissions and crime rates to see if the similarity of the curves was as good as it seemed. It turned out to be even better: In a 2000 paper (PDF) he concluded that if you add a lag time of 23 years, lead emissions from automobiles explain 90 percent of the variation in violent crime in America. Toddlers who ingested high levels of lead in the ’40s and ’50s really were more likely to become violent criminals in the ’60s, ’70s, and ’80s.

And with that we have our molecule: tetraethyl lead, the gasoline additive invented by General Motors in the 1920s to prevent knocking and pinging in high-performance engines. As auto sales boomed after World War II, and drivers in powerful new cars increasingly asked service station attendants to “fill ‘er up with ethyl,” they were unwittingly creating a crime wave two decades later.

It was an exciting conjecture, and it prompted an immediate wave of…nothing. Nevin’s paper was almost completely ignored, and in one sense it’s easy to see why—Nevin is an economist, not a criminologist, and his paper was published in Environmental Research, not a journal with a big readership in the criminology community. What’s more, a single correlation between two curves isn’t all that impressive, econometrically speaking. Sales of vinyl LPs rose in the postwar period too, and then declined in the ’80s and ’90s. Lots of things follow a pattern like that. So no matter how good the fit, if you only have a single correlation it might just be a coincidence. You need to do something more to establish causality.

As it turns out, however, a few hundred miles north someone was doing just that. In the late ’90s, Jessica Wolpaw Reyes was a graduate student at Harvard casting around for a dissertation topic that eventually became a study she published in 2007 as a public health policy professor at Amherst. “I learned about lead because I was pregnant and living in old housing in Harvard Square,” she told me, and after attending a talk where future Freakonomics star Levitt outlined his abortion/crime theory, she started thinking about lead and crime. Although the association seemed plausible, she wanted to find out whether increased lead exposure caused increases in crime. But how?

The answer, it turned out, involved “several months of cold calling” to find lead emissions data at the state level. During the ’70s and ’80s, the introduction of the catalytic converter, combined with increasingly stringent Environmental Protection Agency rules, steadily reduced the amount of leaded gasoline used in America, but Reyes discovered that this reduction wasn’t uniform. In fact, use of leaded gasoline varied widely among states, and this gave Reyes the opening she needed. If childhood lead exposure really did produce criminal behavior in adults, you’d expect that in states where consumption of leaded gasoline declined slowly, crime would decline slowly too. Conversely, in states where it declined quickly, crime would decline quickly. And that’s exactly what she found.

One Response to “America’s Real Criminal Element: Lead”

  1. Calm Says:

    Los Angeles Police Department’s online crime map intended for public use has failed to include nearly 40% of serious crimes reported in the city.
    http://www.latimes.com/media/g.....955242.gif

    More than a hundred retired New York Police Department captains and higher-ranking officers said in a survey that the intense pressure to produce annual crime reductions led some supervisors and precinct commanders to manipulate crime statistics, according to two criminologists studying the department.
    http://www.nytimes.com/2010/02.....crime.html

    While one of the core duties of a police officer is to take crime complaints, the 81st Precinct had a controversial policy that held that if a victim refused to come to the stationhouse and speak to the detective squad, officers should refuse to take the complaint.
    http://www.villagevoice.com/20.....t-precinct

    A Detective Comes Forward About Downgraded Sexual Assaults
    When even attempted rapes are being downgraded to misdemeanors, is the public safe?
    http://www.villagevoice.com/20.....ading-rape

    The NYPD Tapes Confirmed
    The report police hid for nearly two years that corroborates a Voice investigation — and vindicates a whistle-blower the NYPD tried to destroy
    In October 2009, Schoolcraft met with NYPD investigators for three hours and detailed more than a dozen cases of crime reports being manipulated in the district. Three weeks after that meeting—which was supposed to have been kept secret from Schoolcraft’s superiors—his precinct commander and a deputy chief ordered Schoolcraft to be dragged from his apartment and forced into the Jamaica Hospital psychiatric ward for six days.
    http://www.villagevoice.com/20.....-confirmed

    Calm
    http://www.dotandcalm.com/calm.....sCalm.html

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