How Much Did Lead Contribute to Mass Incarceration?

Editor’s Note: This article previously appeared in a different format as part of The Atlantic’s Notes section, retired in 2021.

A reader mentioned something I think is really worth expanding on. He initially shared the sentiments of these readers who lacked any sympathy for the central subject of TNC’s cover story, Odell Newton, who murdered a cab driver at age 16. But then the reader noted a line from an interview Ta-Nehisi did with Ezra Klein:

“Odell Newton, who is in jail for murder, and also nearly died from severe lead poisoning when he was 4.”

That changes things a bit. I’m not sure how bad the damage to Mr. Newton was, but given that he nearly died from lead poisoning, I’m sure it wasn’t nothing. How much of a mitigating factor that is, I don’t know, but it is something for which an accounting should be made. Where I’m from, mental deficits are mitigating factors, even for murderers.

We debated that last point previously in Notes here and here. Ta-Nehisi mentions in his piece how Newton’s lead poisoning almost killed him at age four, and how Newton’s repeated failures to get a G.E.D. probably stemmed from that poisoning, which is proven to cause cognitive and behavioral problems. And Ta-Nehisi notes the racial disparities:

A lawyer who handled more than 4,000 lead-poisoning cases across three decades recently described his client list to The Washington Post: “Nearly 99.9 percent of my clients were black.”

But that’s about it; Ta-Nehisi doesn’t explicitly mention the credible theory that lead poisoning is partly responsible for the spike in violent crime and incarceration of black Americans starting in the 1960s, before the U.S. government in the late 1970s banned the use of lead paint and severely restricted leaded gasoline. One of the most vocal advocates for the lead/crime theory is Mother Jones’s Kevin Drum. Here’s a concise summary from Drum:

Both gasoline lead and lead paint were most prevalent in the postwar era in the inner core of big cities, the former because that’s where cars were densest and the latter because slumlords had little incentive to clean up old buildings. Because African-Americans were disproportionately represented in inner-city populations during the high-lead era, they were disproportionately exposed to lead as children. The result was higher rates of violent crime when black kids grew up in the 70s and 80s.

And from a deep investigation by Drum that became a cover story:

Like many good theories, the gasoline lead hypothesis helps explain some things we might not have realized even needed explaining. For example, murder rates have always been higher in big cities than in towns and small cities. We’re so used to this that it seems unsurprising, but [H.U.D. consultant Rick] Nevin points out that it might actually have a surprising explanation—because big cities have lots of cars in a small area, they also had high densities of atmospheric lead during the postwar era. But as lead levels in gasoline decreased, the differences between big and small cities largely went away. And guess what? The difference in murder rates went away too. Today, homicide rates are similar in cities of all sizes. It may be that violent crime isn’t an inevitable consequence of being a big city after all.

Jim Manzi at National Review scrutinized Drum’s piece and took issue with some of the research he cited, but Manzi’s bottom line isn’t contentious at all:

Drum has made clear that his purpose in doing this article was to get further research and attention on the topic. He has succeeded, and I think it a worthy goal. Before reading his article, I had the intuition that lead exposure should have some effect on crime. Reading the article strengthened this belief. I think it should strengthen this belief in any rational person who has not previously seen this evidence. But that is way short of making a convincing case for spending $400 billion of taxpayer money.

Drum responded to Manzi here. Money quote:

[W]e have multiple prospective studies that associate lead with arrest rates for violent crime in individuals. We have MRI studies showing that lead affects the brain in ways likely to increase aggression levels. We have copious historical evidence of the effect of high doses of lead on workers: for years people said it made them “dumb and mean.” We have medical studies showing that prisoners convicted of violent crimes have higher lead levels in their teeth than similar populations. We have studies linking lead exposure to juvenile delinquency. Dose-response effects litter the literature. And much, much more.

In retrospect, if I were writing my article over again I’d begin with this evidence. I chose to begin with the population studies mainly for narrative purposes, but I think that was a mistake because it led a fair number of readers, like Manzi, to believe that the Reyes paper was the linchpin of my argument. But it’s not. It’s just one confirming piece in an ocean of evidence.

Circling back to Odell Newton, another reader writes:

It’s indeed tragic that he got lead poisoning, which apparently can lead to violent behavior. But … he still killed someone. Dig into the past of most murderers and you will find a child who suffered some terrible harm. It doesn't change what they did later in life. Our criminal justice system is incredibly flawed, but taking these violent people off the street is the only way we have of preventing them from perpetuating more violence.

What do you think? And is there any further evidence or analytical points in the lead-crime theory worth noting here? Please email hello@theatlantic.com and we’ll air it.