South Dakota has been on a prison bender during the past couple decades, incarcerating people at a faster rate than surrounding states even though our crime rate is about the same as our neighbors'. Governor Daugaard wants to address that costly problem with a proposal to reform our parole and probation system and reduce recidivism.

South Dakota's goal should not be to put more people in prison. Our goal should be to keep people from going to prison in the first place. Toward that end, Kevin Drum posts a hefty article in Mother Jones that contends one of the biggest contributors to crime (not to mention hyperactivity, attention-deficit problems, IQ decline, and other health problems) is lead contamination. He cites economic and public health research that finds the use of tetraethyl lead as a gasoline additive correlates tightly with crime rates. When leaded gasoline surged, the crime rate surged about 20 years later. When the U.S. got rid of leaded gasoline, the crime rate dropped about 20 years later. The research Drum cites finds the lead–crime link holding at national, state, and even neighborhood levels. The science is pretty clear: even tiny amounts of lead mess up the parts of the brain that make people behave themselves.

Drum notes that even though we've switched to unleaded gasoline, all the lead we coughed from our tailpipes is still around on the ground. We kick it up and breathe it and our kids pick it up and eat it all the time. And there's still lead in the paint of lots of old houses, which gets released when folks renovate or just slide their windows open and shut. So there are still plenty of health gains to be had by cleaning up lead.

Drum estimates that a serious nationwide program to replace old windows and clean up lead in soil would cost $20 billion per year for twenty years. Adding up just the benefits of increased income from higher IQs and savings from a 10% reduction in crime, Drum estimates we'd get an annual return of $210 billion. Spend a buck on lead mitigation, and you get ten and a half bucks back, with nearly three-quarters of the benefit coming from crime reduction.

But the attention and money we could have been spending on lead mitigation has gone toward building prisons:

At the same time that we should reassess the low level of attention we pay to the remaining hazards from lead, we should probably also reassess the high level of attention we're giving to other policies. Chief among these is the prison-building boom that started in the mid-'70s. As crime scholar William Spelman wrote a few years ago, states have "doubled their prison populations, then doubled them again, increasing their costs by more than $20 billion per year"—money that could have been usefully spent on a lot of other things. And while some scholars conclude that the prison boom had an effect on crime, recent research suggests that rising incarceration rates suffer from diminishing returns: Putting more criminals behind bars is useful up to a point, but beyond that we're just locking up more people without having any real impact on crime. What's more, if it's true that lead exposure accounts for a big part of the crime decline that we formerly credited to prison expansion and other policies, those diminishing returns might be even more dramatic than we believe. We probably overshot on prison construction years ago; one doubling might have been enough. Not only should we stop adding prison capacity, but we might be better off returning to the incarceration rates we reached in the mid-'80s [Kevin Drum, "America's Real Criminal Element: Lead," Mother Jones, Jan/Feb 2013].

We still have to have someplace to put the inevitable bad guys. But a comparable investment in cleaning up lead would reduce the amount we have to spend on building prison cells. Governor Daugaard's proposal to reform our parole and probation system may do some good with people already in the system, but some serious, long-term environmental thinking will keep more people out of the criminal justice system.

Related: The South Dakota Department of Health reminds you that eating venison shot with lead bullets may pose a higher risk of lead contamination than eating pheasants shot with lead pellets.