Could criminal and antisocial behavior be linked to the distribution of lead within a region? That is the question Erik J. Nelson, assistant professor in epidemiology and biostatistics at the Indiana University School of Public Health-Bloomington, in collaboration with lead author Brian B. Boutwell of Saint Louis University, sought to answer in the ecological study “Aggregate-level Lead Exposure, Gun Violence, Homicide, and Rape” Recently published in PLOS One, it is one of the first studies to directly explore blood lead levels as an indicator of firearm crimes, as well as homicide and rape.

Exposure to and subsequent absorption of lead in utero and during early childhood is related to various abnormalities in physiological and neurological growth, such as a reduction in total brain volume and gray matter, which are believed to have a lifelong effect on impulse regulation and general intelligence. A number of lines of study have discovered that diminished prefrontal cortex function is linked to impulsivity, violent tendencies and persistent criminal conduct.

“Lead toxicity is a social and environmental justice issue. Although public health surveillance has worked diligently to track lead exposure, we are missing the big picture that any exposure to lead during childhood carries lasting consequences,” says Nelson.

Using data from ongoing research into lead exposure in St. Louis, Missouri, the team analyzed aggregate blood lead levels of 59,645 children, who between 1996 and 2007 were under 72 months of age and had their blood lead levels tested during that time by the Missouri DHSS Health Strategic Architecture and Information Cooperative, to determine specific indicators associated with violent inner-city crime. The 15,734 crimes reviewed ranged from assault and robbery (with or without a firearm) to any violent crimes involving a firearm to homicide and rape. The researchers divided the number of such crimes committed between 2010–2012 by the size of the population (taken from the 2008–2012 American Community Survey) in each census tract to ascertain the mean crime rate per tract. They also employed indirect standardization to calculate an incidence ratio that is based on the observed crime rate in comparison with the expected rate per crime category.

Study results indicate that, even after adjusting for important sociological variables, blood lead levels elevated by a mere 1 percentage point in children were linked to the perpetration of the violent crimes reviewed, with the exception of rape, which underscores the association between lead and criminality. The team recommends future research investigates the interaction of sociological and biological risk factors.

Nelson concludes, “The underlying message is that we can and should do more to prevent lead exposure, particularly among disadvantaged and minority populations who primarily shoulder the burden of lead exposure, This is one more piece of evidence pointing toward our need to curb lead exposure, especially since we know that lead abatement and prevention efforts are much more cost-effective than the long-term care and treatment of lead-exposed children.”