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Moment that mattered: New York’s day without violent crime

“I am not surprised that there was a day without violent crime in New York. A very rapid reduction in violence has been taking place in the US since the 1990s and is still continuing.

However, I’m not sure that the criminologists fully understand or appreciate the environmental component to the crime problem. One of the key elements of criminal behaviour is the negative effect that lead has on the developing brains of children, particularly on the pre-frontal cortex, the centre of personality and decision-making. The economist Rick Nevin did some of the first work on showing this link at the national level. He noticed that there was a fall in crime about 20 years after the US switched to unleaded gas: reducing the lead in the air reduced lead in children’s blood and – down the line – lowered levels of criminal behaviour.

Now that lead in the air has decreased, the major exposure to lead is taking place from the soil. Children are the most at risk: it’s programmed into a child to do hand-to-mouth activity, they can’t avoid it, their brains don’t develop without it. They explore their environment in that way, it’s genetically programmed. And children’s levels of blood lead is directly related to the amount of lead in the local soil.

We’ve mapped the levels of soil lead in the city of New Orleans, and what we notice is a very strong association between community exposure to lead and violent crime. The police department has looked at our maps and they’ve put their crime report maps on top of our maps and they’re astounded by the fit. There are large hotspots with too much lead and if we can get some control over the lead dust that has accumulated in those communities then we have a chance of further reductions in crime because kids will have lower levels of lead in their blood.

We’re working towards that in New Orleans by bringing clean soil in from outside the city. The problem we have is a lack of funding. If you take a look at the funding that’s available because of the Clean Water Act, you’ll see that BP is spending billions of dollars on cleaning up the Deepwater Horizon oil spill. I can demonstrate that automobile traffic and the use of lead in petroleum has had an enormous impact on the quality of the environment in cities but there is no Clean Soil Act in the US.

One of the frustrations I have is that these are problems that require policymaking that takes a much longer view of the future: we can’t work on just four-year or six-year cycles. It doesn’t fit any of our political frameworks. But we have to start figuring out how to take the long view about the quality of cities.

There was a project done in New Orleans called the Million Dollar Block which tallied the costs of the incarceration of people from a given block. They found the cost to any given block was at least a million dollars per year. The public is paying enormous amounts of money to incarcerate people but it doesn’t change the environment one iota in those communities. If we could apply the same kinds of money to cleaning up lead and making communities safe for children that would ultimately be safer for everyone into the future.”


Howard W Mielke is a professor in the department of pharmacology at Tulane University School of Medicine. His paper, ‘The urban rise and fall of air lead (Pb) and the latent surge and retreat of societal violence’, was published in Environment International in August 2012.

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