Years ago when I was a legal aid lawyer I was always cross-examining psychiatrists in connection with Civil Commitment Hearings.  I got to know one well and he speculated once that some of the cause of mental diseases like schizophrenia might be environmental.  In fact, he suggested that there might be some cause between lead exposure and the disease.  He said this in the mid-90's, and said he thought the effects of childhood exposure to lead might be far greater than people understood.

To be honest, it was the first time someone explained the connection between lead and brain development.  I know, of course, that we had taken lead out of gasoline and paint, but the battle over lead was fought before my time. I did not then understand just how lead effects brain development.  

Since that time I have on occasion made it a point to check to see if he is right.  There was one study done in 2004 that suggested a strong link between prenatal lead exposure and schizophrenia - but I am not aware of any more detailed findings.

What there is significant evidence for is a link between lead exposure and murder - and here the evidence is pretty overwhelming.  I am going to review this in a second, but it is worth making two points about all of this:
1.  We are forever being told by the right about the costs of environmental regulation.  But no one really ever talks about the benefits in a concrete way.  Well, cutting the murder rate is a pretty big fricken benefit.
2.  Why isn't this discussed more?  I mean there has never been a front page article here. I have my own theory - which I will suggest at the end.

I doubt most Americans know how much the violent crime rate has fallen in the United States over the last 30 years.  There are cities in this country (New York, eg) that have fewer murders now than at any time since the 1950's.  

I have occasionally noted this over the past few years here, but what prompts me to write today is a great Mother Jones Article by Kevin Drum. Let's start with a chart:

This chart goes through 2009, but the murder rate declined in 2010 and 2011.  Stop and think about that for a second.  The murder rate declined while the economy tanked.  The murder rate declined while gun purchases increased.

As Drum notes, when the murder rate began falling in the 90's many credited get tough policies like those adopted by Giuliani.  Some said it was a result of a boom in the economy (I well remember reading a NYT article in the late 90's suggesting this).  But as Drum notes, none of these explanations really survive a detailed analysis.  Other cities had murder rate declines that weren't run by Guiliani, and areas that got worse economically saw their crime rates decline.  

The explanation was suggested by Phillip Nevin.  I first heard of this research about 8 years ago -and over time his explanation has gotten stronger.  What he found was this:

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.

America's fascination with cars was unleashing an epidemic: in crime.

What is amazing about this research is you can add the lag time to the removal of lead in other countries - and it works just as well (see, eg, the UK).

The evidence gets better:

ust this year, Tulane University researcher Howard Mielke published a paper with demographer Sammy Zahran on the correlation of lead and crime at the city level. They studied six US cities that had both good crime data and good lead data going back to the '50s, and they found a good fit in every single one. In fact, Mielke has even studied lead concentrations at the neighborhood level in New Orleans and shared his maps with the local police. "When they overlay them with crime maps," he told me, "they realize they match up."
So the psychiatrist years ago was right.  In fact, there is really good evidence that a serious effort to remove all lead from our environment would pay for itself 20 times over.

So why don't more people know about this? Part of the reason has to do with the media and they way it reports the news.  As television news budgets were slashed over the last 20 years, crime reporting has taken the place of more long form reporting - because it is cheaper.  Part of it is because the incidents of mass murder are NOT declining - and those events are so appalling that they justifiably focus people's attention.

But another reason is that the explanation doesn't fit.  If a more secular America is a less violent America, the conservatives aren't going to bring it up.  Certainly prison companies aren't going to bring it up.  Even liberals, with their belief in the connection between crime and economics might be skeptical.  

Originally posted to fladem on Fri Jan 04, 2013 at 09:51 AM PST.

Also republished by SciTech.

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