Photo by James St. John
United States / Pollution

Lead and Crime: An Environmental Victory

Violent crime in America has been on a consistent downward trend for the past two decades. The FBI has reported that from 1992 to 2002, violent crime dropped 34 percent. Public officials and law enforcement agencies have proudly pointed to these crime statistics as indications of legislative and operational success, but perhaps the true credit for our safer streets belongs to something else: environmental regulation that has greatly reduced the levels of atmospheric lead. Passed in 1970, the Clean Air Act phased lead, known to be toxic, out of gasoline, which was intended to improve the physical health of people living in the US. However, it seems that this legislation had an unintended effect that was felt twenty years later: a sharp reduction in criminality.

Among the first to study this surprising link was Dr. Jessica Wolpaw Reyes, who explored the idea while writing her dissertation at Harvard. She published a full study in 2007 while teaching public health policy at Amherst College. In this paper, she first established that the Clean Air Act had a significant impact on lead exposure in the United States across all demographics. For the entire population, the mean concentration of blood lead levels dropped from 16 μg/dL in 1976 to only 3 μg/dL in 1991. The effect was even more pronounced in children below age 5, with 90 percent of children in 1976 at above 10 μg/dL while 90 percent of children in 1990 had blood lead concentration below that threshold. Dr. Reyes then compared crime rates in cohorts of children born in the 1970s, when lead gasoline was common, to children born in the 1980s, who benefitted from the EPA regulations during their early development. What she found was damning – after controlling for exogenous factors, such as economic conditions, she estimated that the elasticity of violent crime with respect to lead was approximately 0.8. In other words, for every 10 percent increase in lead exposure during childhood, there was an 8 percent increase in violent crime incidence as the children grew to adulthood, and for decades our automobiles had been pumping enormous amounts of the toxic metal into the atmosphere for our children to breathe.

Since then, her hypothesis that childhood lead exposure leads to increased risk of adult criminality has been researched and largely upheld by scientists and sociologists. A 2010 study examined six different cities in the U.S. and found that lead levels and crime rate were correlated even at the neighborhood level – heat maps for soil lead levels and crime matched very well within the same city. From a medical perspective, there is also a large base of support. Lead has been known for centuries to be linked to a variety of mental defects, and modern research has continued provide even more evidence for this conclusion. MRI’s show differences in gray matter, involved in impulse control, between children with long-term lead exposure and those without. Lead exposure during childhood has since been associated with lower IQ, ADHD, and increased aggression, which in turn can lead to poor academic performance, delinquency, and other antisocial behavior. Beyond its psychoactive effects, lead has long been known to have extremely harmful to humans physiologically. Lead poisoning inhibits the production of hemoglobin, leading to respiratory problems, and also interferes with calcium metabolism, which is involved in an enormous number of biological cascades within the body.

Though lead exposure for most people in the U.S. has been dramatically reduced by regulation over the past decades, it still remains a significant environmental issue in some cities.  According to a report to Congress, about 17% of children in Standard Metropolitan Statistical Areas are exposed to environmental sources of lead at concentrations that place them at risk of adverse health effects. Significant amounts of lead no longer escape into the atmosphere through combustion of gasoline, but in these aged centers of industry, crumbling buildings – and the lead in their degrading paint – still expose thousands of children to concerning levels of lead. The toxic metal finds its way into the soil, dust, and drinking water of people living in these areas, with debilitating effects. Chronic exposure to low levels of lead has continually been cited in scientific and sociological literature as a public health concern and a problem that disproportionately affects socioeconomically disadvantaged groups due to poor housing and impoverished, industrial neighborhoods. These same groups often suffer from high rates of gang violence and crime. While there are certainly other factors at play, if these environmental contaminants were to be dealt with today, the social problems associated with urban decay may be at least slightly alleviated in the future.

Despite all of the current research that continues to build a mounting body of evidence that lead exposure has deleterious effects on life trajectory, little has been done to clean up high-risk areas in Chicago and other major urban-industrial centers. Policy makers cite lack of funding, but should address these areas, as the quantified social benefit has been calculated to be about 20 times the cost of remediation. What is truly tragic about the whole issue is that despite the fact that children have no say in the environment in which they are raised, they themselves are most at risk for these negative side effects. Children, whose growing bodies are constantly consuming resources to build up organs, bones, and tissues, uptake significantly greater amounts of environmental lead than adults. Additionally, children are more likely to ingest lead-laced dirt and dust by engaging in hand-to-mouth behavior, which also significantly increases the total amount of lead they are exposed to.

Some industry lobbyists and politicians argue against increased environmental regulation, citing its high costs and perceived inefficiency. For many, the idea of environmental policy conjures warm, but not obviously practical, images of protecting biomes and endangered species, but as the case of lead demonstrates, there is a tangible benefit to humankind to be gained from protecting the quality of the environment. Beyond clearing lead from our air and soil, economic regulation in general could have a variety of positive effects on economies worldwide. A 2009 report by the Sustainable European Research Institute asserted, among other positive outcomes, that environmental policy: enhances productivity, stimulates innovation, increases employment, improves balance of trade, strengthens capital base, and promotes economic cohesion. Regardless of whether or not one agrees with the economic models used in that particular study, it is undeniable that the Environmental Protection Agency provides a crucial social service that generates concrete value for the nation, not just for the animals in its wilderness, but also for the humans living in its concrete jungles.