The Frontal Cortex

Lead and Crime

By now, just about everybody knows about the two competing hypotheses that attempt to explain the drop in crime in the late 1990’s. There’s the “broken windows” theory, which assumes that crime is contextual, and that cracking down on the small misdemeanors (like public drunkenness, loitering and graffiti) eliminates the conditions that encourage felonies. And then there’s the Freakonomics theory, which is that the legalization of abortion in 1973 reduced the number of unwanted births, which led, a generation later, to a reduction in the number of criminals roaming the streets.

But now there’s a new hypothesis:

The theory offered by the economist, Rick Nevin, is that lead poisoning accounts for much of the variation in violent crime in the United States. It offers a unifying new neurochemical theory for fluctuations in the crime rate, and it is based on studies linking children’s exposure to lead with violent behavior later in their lives.

What makes Nevin’s work persuasive is that he has shown an identical, decades-long association between lead poisoning and crime rates in nine countries.

“It is stunning how strong the association is,” Nevin said in an interview. “Sixty-five to ninety percent or more of the substantial variation in violent crime in all these countries was explained by lead.”

Through much of the 20th century, lead in U.S. paint and gasoline fumes poisoned toddlers as they put contaminated hands in their mouths. The consequences on crime, Nevin found, occurred when poisoning victims became adolescents. Nevin does not say that lead is the only factor behind crime, but he says it is the biggest factor.

The centerpiece of Nevin’s research is an analysis of crime rates and lead poisoning levels across a century. The United States has had two spikes of lead poisoning: one at the turn of the 20th century, linked to lead in household paint, and one after World War II, when the use of leaded gasoline increased sharply. Both times, the violent crime rate went up and down in concert, with the violent crime peaks coming two decades after the lead poisoning peaks.

Other evidence has accumulated in recent years that lead is a neurotoxin that causes impulsivity and aggression, but these studies have also drawn little attention. In 2001, sociologist Paul B. Stretesky and criminologist Michael Lynch showed that U.S. counties with high lead levels had four times the murder rate of counties with low lead levels, after controlling for multiple environmental and socioeconomic factors.

In 2002, Herbert Needleman, a psychiatrist at the University of Pittsburgh, compared lead levels of 194 adolescents arrested in Pittsburgh with lead levels of 146 high school adolescents: The arrested youths had lead levels that were four times higher.

“Impulsivity means you ignore the consequences of what you do,” said Needleman, one of the country’s foremost experts on lead poisoning, explaining why Nevin’s theory is plausible. Lead decreases the ability to tell yourself, “If I do this, I will go to jail.”

Obviously, crime is an extremely complex social phenomenon, and it’s ridiculous to try to associate a temporary drop in criminal activity with any single explanation. I’m sure all three phenomenon – the reduction in lead exposure, the legalization of abortion and stricter policing – played some role in the drop in crime.

That said, there are other extremely important reasons to reduce lead exposure.


  1. #1 Tegumai Bopsulai, FCD
    July 10, 2007

    My own theory is that criminals cause crime. There is a 100% correlation in that all crimes are committed by criminals.

  2. #2 Daniel
    July 10, 2007

    So? Cute, but doesn’t mean much (referring to the previous comment).

  3. #3 Hank Roberts
    July 10, 2007

    Are we distinguishing street crime, white-collar crime, and corporate crime here?

    Of course, given the news about heavy metals in sushi, there may be less difference than you’d think at first.

    I would not dismiss this out of hand, it’s an interesting correlation. After all, we know how the industry PR works in obscuring what they know. Wanta bet the lead industry knows more about this?

  4. #4 Drat
    July 10, 2007

    The apparent decrease in US crime lately is due to two things.

    1. Most of the occurrences of the crimes of impersonation, counterfeiting, and fraud are no longer counted as crimes but as ‘identity theft’ (a concept so daft only a lawyer could dream it up).

    2. Almost all of white collar crime goes unreported for the simple reason that the police will not take reports. This includes business crimes, corporate crimes, and the criminal acts of mercenaries.

  5. #5 tekel
    July 11, 2007

    Hank: read the article. Violent crime.

  6. #6 Threnody
    July 12, 2007

    I have been researching this subject for several years. My work during military service exposed me to countless endocrine disruptors, neurotoxins and carcinogens in the form of particulates, vapors, liquids and solids. Lead, Silver, Antimony, Bismuth, Zinc, Copper, Chromium, Colophony, polyurethanes, varnishes, epoxies, alcohol, caustic cleaning agents, Teflon and PVC coatings are a few of the hazards I was exposed to on a daily basis, hazards that now require strict safety protocols.

    Exposure is considered a precursor to criminal behavior and implicated in PTSD, Alzheimer’s and other dementias, Lou Gherig’s Disease, ADHD and Multiple Sclerosis. Women are more susceptible than men, thanks to hormonal fluctuations. Children are at the highest level of risk because of their higher energy levels and developing systems. Lead is stored in the body until an event (stress, accident, childbirth, chemo) triggers its release; it can remain hidden for years.

    Yes, the lead industry knows. Financial loss and legal ramifications prevent admission of their guilt, which makes my fight for compensation one heckuva challenge.

  7. #7 rachel
    July 12, 2007

    Why is it that economists are the ones theorizing on the causes of violent crime?

  8. #8 Art in FL
    July 17, 2007

    Makes me wonder. This concerns lead but many elements have effects on behavior.

    I have seen people change from nice to very mean and aggressive after welding for a time. I looked it up at the time and found that welders sometimes are exposed to fairly high concentrations of manganese and this may account for the change.

    Inadequate levels, well below pharmaceutical levels, of lithium have also been linked with violent and destructive behaviors.

    This article shows a seeming connection between inadequate or excessive exposure to a variety of minerals, vitamins and metals:

    All of this raises the question; If lead, by it self, correlates well to violent behaviors I wonder if tossing in lithium deficiency, manganese poisoning and a lack of iron wouldn’t account for some of the discrepancies.

    What if virtually all violent behavior could be accounted for by environmental factors?

    We presently add fluoride to most municipal water and the payoff in dental health is a great benefit to the nation. With only a small down side.

    Would adding lithium also make sense? Violent crime and destructive antisocial behaviors are a multi-Billion dollar burden on the nation. This article suggests addition of as little as 1 mg of lithium a day could make a profound change for a 70Kg individual:

    If not the general population perhaps just the water in jails. Less violence in lock-up sounds good.

    The idea of a correlation between the stuff going into people and the behaviors coming out is a fascinating area. I see a bright future for this field.

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