Though you probably haven’t heard much about it, the crime rate has dropped dramatically since the early 1990s. The rate of violent crime has fallen to the level of the late 1960s, and what’s more, those gains have been sharpest in the big cities. America is safer than it’s been in two generations, and there’s no reason to think the trend won’t continue.
What’s responsible for this change? Is it better education? More draconian punishment of criminals? The internet pulling kids off the street and giving them somewhere else to vent their antisocial behaviors? Maybe. But one factor appears to play perhaps the most significant role in making our society less violent: the elimination of Pb(CH2CH3)4 — tetraethyl lead — from our environment
A new article by Mother Jones’ Kevin Drum documents how lead pollution skyrocketed after World War II, when soldiers came home, bought cars and moved out to the suburbs. Lead was used as an additive in gasoline to reduce knocking and pinging — its elimination is the reason that standard gasoline today is called “unleaded.”
Of course, lead is a neurotoxin, and a potent one at that. The introduction of so much lead to the environment led to behavioral problems, reduced intelligence and very likely, increased crime. Lead use increased in the late 1940s and early 1950s, and twenty years later — one generation — crime began to rise. As the children exposed to lead became adults, they became more violent and more willing to commit criminal acts.
It didn’t last. In the 1970s, cars switched over to unleaded fuel — lead didn’t work well with catalytic converters — and the level of lead pollution dropped again. Twenty years later — one generation — the crime rate followed suit.
Correlation is Causation
As Drum documents, if the link between lead and crime was confined to the US, the link between crime and lead could be dismissed as a case of mere correlation. That’s not the case. Rick Nevin, a researcher formerly with the US Department of Housing and Urban Development, has looked at crime rates around the world, in countries that began using lead additives in fuel later, or stopped using it earlier. The same curve shows up in each country: 20 years after leaded fuel is introduced, crime rises. 20 years after it’s phased out, crime drops.
When you see how lead is used by the body, it’s clear why. Lead disrupts the formation of “white matter” in the brain, the neurons that build connections between our “gray matter.” These make the connections less efficient, causing a corresponding drop in intelligence. Lead also affects the frontal lobe — the part of the brain responsible for higher-level thinking and impulse control, the part most responsible for what we like to think of as human behavior.
Obviously, lead doesn’t make everyone into a monster — that would be too easy. What it does, though, is make it more likely that people who might have been disruptive or impulsive to become instead violent and criminal. Every person it tips over the edge makes the world just that much more dangerous.
The more lead in the environment, the more people tipped over the edge. That’s one reason why violence exploded in big cities in the 1970s and 1980s — more people meant more cars, which meant more lead pollution. Add in the fact that highways were often run straight through the poorer parts of town, where children had less access to support, and we were creating a situation where crime could not help but rise. Indeed, one fascinating part of the drop in crime has been the murder rate, which is now roughly the same in cities of all sizes; big cities are not inherently more violent, not when we aren’t actively polluting the environment with lead.
Lead Hasn’t Disappeared
It would be nice to simply pat ourselves on the back, congratulate ourselves for accidentally fixing the crime problem. Unfortunately, that’s not the case. For one thing, that atmospheric lead settled out into our soil over the years, and it’s still there. Highways still run through the poorer parts of town; kids growing up in those areas are playing on lawns still contaminated with lead.
Our houses, too, are full of lead, at least if they were built before 1960. Lead windows and lead paint are often still in place today; they can’t be simply yanked out, because that risks changing long-term, low-level lead exposure into acute lead poisoning. The paint and windows can be removed, but it needs to be done carefully, by trained contractors; lead abatement is not easy or cheap.
That said, lead abatement is incredibly cost-effective. A $20 billion a year investment in lead abatement could lead to a $30 billion a year boost to the economy just based on the impact on intelligence. The crime reduction could produce benefits over $150 billion a year.
Of course, lead reduction isn’t sexy. We like to think that people are rational, and that crime can be eliminated through a combination of education and punishment. Outlaw the right drug, build another jail, start a midnight basketball program — these are seen as things that will reduce crime. We don’t like to think that it could be as simple as a molecule.
People are ultimately just bags of chemicals, though. Throw those chemicals out of whack and you can get bad outcomes. We’ve spent hundreds of billions, if not trillions, of dollars on building new prisons over the past forty years. That money would have been better spent on lead abatement.
More than that, Drum’s article is a reminder that when we improve our environment, we improve our own quality of life. Eliminating lead from gasoline was not done to reduce crime. It wasn’t even done to reduce lead. It was done to reduce pollution — the catalytic converter is designed to reduce tailpipe emissions. Thousands of lives have been saved by that change, simply because of the reduction in crime. If we focus on improving our environment, what other happy benefits will we find?
Image Credit: Steve Snodgrass