By the early 1990’s violent crime in the United States had spiked to unprecedented levels. In 1991, the violent crime rate per 100,000 people was 758.2. In contrast, in 1961, the rate was only 158.1. This amounted to a 380% increase over three decades. Policymakers were dealing with an epidemic that was gripping the nation. This led to a surge in tough on crime legislation passing through the nation’s political corridors. Stop and frisk, mandatory minimums, and three strikes laws were just a few of the tactics used to try to curb the wave of violence.
As these new policies restructured the criminal justice system and policing in America, the results began to speak for themselves. Violent crime in the late 1990’s and into the 2000’s decreased substantially. By 2014, the rate had fallen to 361.6; a level not seen since 1970. It appeared that the politicians from both sides of the aisle had come together and figured out a solution that had actually worked. But was the tough on crime legislation really a success or was there something more at play?
The public and politicians had largely bought into the tough on crime narrative, but the data and graphs were telling a different story. The crime rates had already decreased before the legislation had taken root. In addition, violent crime rates decreased in cities that didn’t use tough on crime tactics. As it turns out in the late 1990’s, an economic consultant, Phil Nevin, and a Harvard graduate student, Jessica Reyes, had each independently stumbled on a new postulation behind the decrease in crime. It was childhood exposure to lead.
Data compiled through separate studies from cities in the U.S., as well as from cities around the world, revealed that as the public’s consumption in lead increased violent crime increased and conversely when lead levels decreased so too did the rates of violent crime. When Mother Jones interviewed Phil Nevin for a report in 2013, he was asked if he had ever found a country that didn’t fit the (lead) theory. “No,” he replied. “Not one.”
According to the Environmental Policy as Social Policy? The Impact of Childhood Lead Exposure on Crime report released by Jessica Reyes:
“Childhood lead exposure can lead to psychological deficits that are strongly associated with aggressive and criminal behavior. In the late 1970s in the United States, lead was removed from gasoline under the Clean Air Act. Using the sharp state-specific reductions in lead exposure resulting from this removal, this article finds 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 may cause further declines into the future. The elasticity of violent crime with respect to lead is estimated to be approximately 0.8.”
Today, more and more studies have examined the damaging effects that lead has on the brain, and the Environmental Protection Agency now states that there is “no demonstrated safe concentration of lead in blood.”