Lead exposure in childhood is linked to antisocial behavior in adolescence, suggests a new study published in Criminology.
Children might come into contact with the element through soil, house paint, water, toys and other items. The U.S. Centers for Disease Control and Prevention estimate that about half a million children aged 1 through 5 have elevated blood levels (about 5 micrograms per deciliter) nationwide. Disparities exist in exposure by race and socioeconomic status.
Recent crises over lead in the drinking water in Flint, Michigan and other American cities highlight the continued danger of exposure in the 21st century.
Researchers at Harvard University probed one area in which lead exposure might bear long-term detrimental effects. The study, published in 2018 in Criminology, looked at associations between lead exposure and adolescent delinquency.
The researchers analyzed data collected over 18 years that began with 1,255 infants in Chicago. The data included blood lead levels, parent reports of delinquency and official arrest histories. Parental reports of delinquency covered a number of antisocial behaviors, including whether the child: “destroys things belonging to his/her family or others; displays cruelty, bullying, or meanness to others; disobe[ys] at school; doesn’t seem to feel guilty after misbehaving; and lies or cheats.”
The authors found a significant relationship between lead exposure and antisocial behavior in childhood and adolescence. They indicate that a 1 microgram per deciliter increase in average blood lead levels is associated with a 0.92 point increase in adolescents’ ratings along the antisocial behavior scale, which ranges from 0 to 10.
The researchers conducted two other tests to lend support to their causal interpretation of this finding. Further, they tested other variables to examine whether these factors might also play a role in the relationship between lead exposure and antisocial behavior. The researchers indicate that antisocial behavior in early childhood does not mediate the relationship between lead exposure and adolescent antisocial behavior. “Childhood impulsivity and anxiety or depression also do not appear to mediate lead’s effects on antisocial behavior,” they write.
They conclude, “… the biological assays of lead exposure in childhood directly predict adolescent antisocial behavior using three different modeling strategies and controlling for theoretically informed confounding factors and potential mediating pathways.”
The researchers did not find a direct link between lead exposure and arrest. They suggest that this might be explained in part by declining crime in Chicago and institutional practices that discourage arrests for adolescents.
“Our results point to the utility of considering lead’s early impact on the brain and neurotransmitter systems, which increases the likelihood of children and adolescents responding to challenges in their social contexts in ways that provoke rejection by parents and, we further hypothesize, larger society,” the authors write. Given the link between exposure to lead and delinquent behavior, they suggest “….environmental policy is sound criminological policy as well.”
For more on lead poisoning, consult our comprehensive roundup, which features recent research and governmental resources on the topic.