Scientists link early-life lead exposure to heightened risk of criminal behavior in adulthood

Exposure to lead in the womb or in early childhood may be connected to an increased risk of engaging in criminal behavior in adulthood, a new analysis has found.

Although previous studies have shown statistical associations between lead exposure and criminal behavior at an entire-population level, scientists at George Washington University sought to understand how such connections present at an individual degree.

Their review, published Tuesday in PLOS Global Public Health, ultimately identified “significant relationships between lead and damaging patterns of behavior,” even when lead blood concentrations were very low.

“The evidence we found points in the direction of lead exposure being associated with biological effects in children that have long-term behavioral consequences,” said lead author Maria Jose Talayero Schettino, a George Washington graduate student, in a statement.

While Talayero Schettino stressed more individual-level data must be collected to bolster the connection between childhood lead exposure and adulthood criminal behavior, she urged world leaders “to implement policies to prevent lead exposure.”

Contact with lead can cause cardiac issues, kidney damage, immune system dysfunction, reproductive difficulties and impaired neurodevelopment function in children. Exposure can come from many sources, such as industrial waste, batteries and paints, as well as certain toys, cookware and ceramics.

Talayero Schettino and her colleagues conducted a systematic review of 17 previous studies that in one way or another addressed the possible connection between individual lead exposure and antisocial behaviors, including crime.

The studies, which incorporated a variety of ways to measure lead levels — through blood, bones and teeth — looked at the impacts of exposure at different ages, including in the womb or early childhood, later childhood, adolescence and adulthood.

In addition to involving an assortment of methods, these studies also revealed a broad spectrum of findings, Talayero Schettino and her colleagues noted.

Some studies, for example, showed no statistical associations between early childhood exposure and later delinquency. Meanwhile, one article found a connection with antisocial behavior, but not with arrests.

On the other hand, several studies revealed links between early childhood exposure to lead and later arrests — including drug-related arrests. Outcomes that showed significant associations with lead exposure predominantly involved an arrest, incarceration or conviction of some type, according to the review.

To account for potential bias, the authors used a tool called ROBINS-E that helped them determine which studies were the most statistically robust.

By employing this tool, whose name stands for “Risk of Bias in Non-Randomized Studies of Exposure,” the scientists could pinpoint factors like confounding bias, selection bias, exposure misclassification, missing data, outcome measurement issues and problems with reporting.

One limitation that challenged the researchers was the varying definitions of criminal, aggressive and antisocial behaviors in each study. Also complicating matters was the scarcity of studies available — which resulted in wide geographic and demographic gaps.

While the authors reiterated the need for more individual-level evidence that would reinforce the associations found in their analysis, they stressed that policy interventions on lead exposure are critical to safeguard public health.

“Policy action to prevent lead exposure is of utmost importance as our research shows an excess risk for criminal behavior in adulthood exists when an individual is exposed to lead in utero or during childhood,” the authors said in a joint statement. 

“Preventing lead exposure is crucial to safeguard public health and promote a safer society for all,” they added.