Did Banning Lead Lower Crime?

The major news media (see for instance here and here) have been reporting recently on the hypothesis that banning lead from gasoline caused a reduction in crime. This follows a similar article in the Washington Post a few months ago, which I blogged about at the time.

Since a lot of people have written to us lately asking for comment about the lead/crime connection, I’m going to go ahead and reprint here what I wrote back in July:


Over the weekend, the Washington Post published an article suggesting that much of the decline in crime in the 1990s may have been due to the reduction of childhood lead exposure after the removal of lead from gasoline and house paint.

This is an intriguing hypothesis. There is evidence on an individual level that high exposure to lead is harmful to both IQ and the ability to delay gratification, two traits that could enhance the attractiveness of crime. There is also some suggestive time-series evidence of a relationship: the rise and fall in lead exposure at the national level match the rise and fall in crime. Still, although both Post reporter Shankar Vendantam and the cited economist, Rick Nevin (whom I’d never heard of), appear quite convinced by the time-series data, I am not. When you have a variable like crime that goes up for a long time then goes down for a long time, it is easy to find other variables that share that pattern and appear to have a causal impact, even though the relationship is completely spurious.

About seven years ago, Michael Greenstone and I tried to look into this same issue using airborne lead measures at the local level, as well as other approaches. We ultimately gave up without finding anything. That largely soured me on the lead/crime link.

Recently, however, Jessica Wolpaw Reyes at Amherst has put together what appears to me to be the most persuasive evidence to date in favor of a relationship between lead and crime. Rather than looking at a national time-series, she tries to exploit differences in the rates at which lead was removed from gasoline across states. I haven’t read her paper with the care that a referee would at an academic journal; but, at least superficially, what she is doing looks pretty sensible. She finds that lead has big effects (and, for what it’s worth, she also confirms that, when controlling for lead, the link between abortion and crime is as strong or stronger as in our initial study, which did not control for lead.)

Roger Masters, a professor at Dartmouth, has also been doing interesting research on this subject, although I am also not very familiar with his work.

It will be very interesting to see how this research agenda plays out. If it can be shown here and in other areas that environmental factors have powerful and long-lasting impacts on human behavior, it may dramatically change the way we think about public policy.


personally, i'd jump for joy if crime was exacerbated by leaded gasoline, or poor testing scores for school kids were the result of brain-poisoning from PBDEs and such.

that means it is easy to fix. just ban the stuff. we don't really have to do anything (like overhaul the education system, or some other large, difficult change). it also makes us feel better, since if there were no lead then we'd all be less violent, and that would be nice. if there were no poly-bromated-whatsits then all our kids would be smart.

i'm not putting down the idea of a link. there may well be one, and banning lead in gas was imho a good idea. rather, i am expressing my ideas about what a link means to our worldview.

Matthew Kabrisky

I agree, the plural of anecdote is not data. My wish would be to add another line of study of adult individuals who were, presumably, heavily leaded as children. Namely: how did they turn out over a long period of time. Currently the evaluation of the effect of lead on children is based on IQ tests of the children.

Many have questioned what IQ tests even measure. There are enough of us geezers, who were exposed to heavy lead ingestion, to add another line of lead-effect studies on really long term effects.

Matthew Kbrisky


I wrote a paper for an environmental science class theorizing this in the early 90's in undergrad (while I worked in LAw enforcement no less). My professor tossed it out as nonsense. I am now convinced it has been many factors including the broken windows approach and using GIS based targetting strategies to employ a performance based supervision of the forces.


Oh good, more excuses for government meddling!


I think that you are running into the old problem that correlation does not equal causation. It would be equally valid to say that the improving circumstances of technology, economics and wealth which made banning leaded gasoline possible in the first place also was responsible for the reduction in crime.

I am sure you have heard of that study which showed that the increase in global temperature was correlated with the decline of pirates with the implication that to stop global warming we need more pirates.

With all of your crime related postings have you ever considered that as education, wealth and access to technology improves that criminals simply move to NON-violent crime which these sorts of crime statistics tend to ignore? I mean why rob a bank when it is easier and less risky to just do identity theft, corporate fraud or sub-prime lending.


So will there be a reduction in crime in China as they are forced to make changes in materials previously containing lead in order to sell products in the US?


All roads lead to Rome?

Dan W

An NYT story says that legality of abortion doesn't affect its rate:


A comprehensive global study of abortion has concluded that abortion
rates are similar in countries where it is legal and those where it
is not, suggesting that outlawing the procedure does little to deter
women seeking it...

How does this affect your theory that legalized abortion led to reduced crime?

Anna Turtle

This blog attracts the worst commenters... maybe it's time to shut comments off.


Re: #7

Interesting that Anna would suggest turning off comments, depriving everyone else of the privilege to comment instead of choosing to ignore the comments section herself.


It's "meddling" to prohibit the burning of fuel laced with toxic heavy metals, spewing poison into the atmosphere? Not the most glaring example of overbearing government I've ever seen, but more power to you, mgroves. Clearly eating leaded paint chips as a child has made you a more interesting person; why should future generations of children be denied their right to enjoy delicious wall candy?

Eric Crampton

Anyone having problems downloading the Jessica Wolpaw Reyes paper might have more success over at the NBER website: http://nber15.nber.org/papers/w13097.pdf


If I remember correctly, there was a study on higher incidence of ADHD among people with higher lead exposure (U of Cinci?). Isn't there high incidence of ADHD among inmates? Does this mean reduction in lead exposure lead to lower incidence of ADHD, thus, reducing crime rates?

Matthew Kabrisky

I was born in 1930 and I grew up in NYC in the height of the tetraethyl lead gasoline age, lived in houses slathered with lead paint and featured lead pipes for at least part of their plumbing. I think that the data show no differences between we leaded children and those who now have low measured lead levels in this new age where we have striven to reach very low lead levels in certainly my grandchildren and the rest of their cohort. I am typically educated: BS, MS, PhD all in electrical engineering and if you Google: Kabrisky, you'll see the sort of work that I've done for the past 50 years. Now only a nit would say that lead is not poisonous. There IS some level that WILL damage and diminish you, but I've not seen the sort of analysis that will give quantitative lifetime effects for lead levels that this society has inflicted on many of us.

I should add that have been able to pass for a physically normal person, and in fact served ten years as an Air Force pilot.

Matt Kabrisky



nascar still uses lead based gasoline. does that mean that nascar fans who attend races are more likely to commit a crime? accounting for other variables of course.

nascar is looking to move away from lead based gasoline soon, so it looks as though a natural experiment is about to happen. not to mention nascar is either #1 or #2 as a spectator sport in the US depending on your source, so at least you'd have a large sample size.



It is hard to substantiate such claims as controlled experiments with humans are banned. However, a strong correlation between lead ingestion and crime is possible. I can't recall exactly the study done on concentration of lead in cocoa beans grown in the Ivory Coast, Ghana and other African countries where lead content of gasoline is still unregulated. This would mean that it goes down the food chain in the production of chocolate and other cocoa products. If this was the case there should be a similar trend observable in the cocoa-growing countries. Absent such data, it could only be surmised and attributed to coincidence.

Pure lead and its industrial production would also show clusters in Australia, China and Peru which accounts for more than half of the world's output. The same can be done in U.S. states that produce lead.

Davis Straub

Check out studies of children from Kellogg, Idaho to find clusters.


I guess it is only a matter of time that some lawyers will use this study as a defense for violent criminals. "Not guilty, your honor, because my client ingested lead when growing up. Therefore, the environment in which he was raised is responsible for the criminal behavior."

This reminds me of the Twinkie defense employed in a case years ago in S.F.

BTW, I had a professor that nibbled on a pencil while pondering some issues. He did not show any sign of mental degradation.


Here's a thought:

How well does propensity to commit a crime correlate with:

- being born into a low income household
- poor educational opportunities
- economic inequality: nationally and locally


Re: #13 - Kabrisky, your personal accomplishments are impressive. I hope that in all your education and experience, you learned that (1) arguments based on authority are weak; and (2) basing your personal opinion on anecdotal evidence, with a sample size of 1, spanning 8 decades by way of comparison, is not the most robust method for determining whether a variable has an impact on a given outcome.