A study recently published in PloS Medicine by researchers in Cincinnati has once again attempted to shed light on a question that has plagued the criminal justice system for ages: What causes violent crime?

This study, and a number of others published in the last several years, takes a hard look at the impact of lead exposure in young children and the likelihood of criminal activity in their later adulthood. Following 250 people born between 1979 and 1984 in Cincinnati’s dilapidated inner city, where lead exposure from crumbling paint in old houses is commonplace, researchers found a powerful correlation between an increase in childhood blood lead levels and an increase in later involvement in violent crime. This increase was explained by the impact lead in a child’s blood has on cognitive development: namely a marked decrease in volume of the portions of the brain associated with judgment, reasoning, mood regulation, and some components of attention.

This study is extraordinary in its ability to take a known problem, lead exposure, and tie it to another known problem, violent crime. For over a century, scientists and criminologists have attempted to find any information that would explain why an individual turns to violent crime. The criminal justice community has always struggled with whether to attribute violent criminal tendencies to some sort of genetic component (Nature), or whether there could be something in an individual’s upbringing that made them choose or be forced to engage in criminally violent behavior (Nurture). While researchers and criminologists rarely plant themselves in one camp or the other, how the two come together is difficult to explain in any sort of broad context. Basically, how do you design an effective criminal justice and legal system if you can’t decide whether people are born to be criminals, choose to be criminals, or are a combination of both?

For an interesting look at how crime can be shaped by a person’s environment, and not prenatal influences, check out Marcus K. Felson’s Crime and Everyday Life.

Coming soon:  The Law Blog will discuss potential liability issues tied to lead-tainted toys.