Research in recent years has uncovered a strong connection between reductions in lead pollution and the decline in violent crime in the U.S. Writing in Jones this month, Kevin Drum discusses the research of Rick Nevin, a consultant who began researching lead pollution during the 1990s for the U.S. Department of Housing and Urban Development (HUD). Nevin’s research has shown that the rise and fall of atmospheric lead produced by leaded gas closely corresponds to a similar rise and fall of violent crime.

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Violent crime rates, writes Drum, “followed the same upside-down U pattern. The only thing different was the time period: Crime rates rose dramatically in the ’60s through the ’80s, and then began dropping steadily starting in the early ’90s. The two curves looked eerily identical, but were offset by about 20 years.”

In a paper published in in May 2000, Nevin demonstrated, Drum says, 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.” In a 2007 paper, Nevin used worldwide data to support the same conclusion in country after country.

In a working paper published in 2007 by the National Bureau of Economic Research, Jessica Wolpaw Reyes used state-by-state data to show that “the reduction in childhood lead exposure in the late 1970s and early 1980s is responsible for significant declines in violent crime in the 1990s” and that that reduction “may cause further declines into the future.” This year, a paper in by researchers from Tulane and Colorado State universities established the same correlation in six U.S. cities.

Drum writes, “Groups of children have been followed from the womb to adulthood, and higher childhood blood lead levels are consistently associated with higher adult arrest rates for violent crimes.” Violent crime used to be disproportionately high in large cities compared with small ones. Big cities typically have a lot of cars in a small area. In the post-World War II era, that meant high concentrations of lead in the atmosphere. But as atmospheric lead decreased, so did the disconnect in violent crime between large and small cities. Now the rates are similar.

Neurological research has now proven the connection between lead and brain damage. Drum writes that “it turns out that childhood lead exposure at nearly any level can seriously and permanently reduce IQ.” According to the EPA, “there currently is no demonstrated safe concentration of lead in blood, and adverse health effects can occur at lower concentrations.” Research has shown that high lead exposure during childhood results in damage to the part of the brain that controls aggression. Even very small blood levels have been connected to attention deficit/hyperactivity disorder (ADHD).

Unfortunately, writes Drum, lead is still a danger today. Much of the lead that was emitted during the postwar period persists in the soil and can be reintroduced into the atmosphere through dust. Also, many older buildings still contain old lead paint. Cleanup of lead from soil and old window frames (the most dangerous location) would cost about $20 billion yearly for the next 20 years, Drum estimates. That sounds like a lot, but he also estimates the benefits at up to $150 billion per year.

+ Rick Nevin

Via Mother Jones

Photo credits: Tailpipe by Ruben de Rijcke via Wikimedia Commons; Handcuffs by .v1ctor. via Flickr