While lead exposure as a child has been linked to a number of serious medical and developmental problems, new research raises questions over claims that children with high lead blood levels early in life may be more likely to engage in criminal activity and violence.
In a study published this week in the medical journal JAMA Pediatrics, researchers from the U.S., New Zealand and Sweden indicate that blood lead levels were not a predictor of consequential criminal outcomes, offenses, convictions, recidivism or violence.
The findings go against long-held beliefs by some that lead poisoning can contribute to the likelihood of criminal activity.
In this latest study, researchers looked at data on 553 New Zealanders, who were observed for 38 years and whose blood lead levels (BLL) were measured at 11 years of age. The study examined their criminal convictions, recidivism rates, whether crimes were violent or non-violent, and self-reported crimes at a number of ages.
“Overall, associations between BLL and conviction outcomes were weak,” the researchers found. “The estimated effect of BLL was lower for recidivism than for single convictions and lower for violent offending than for nonviolent offending. Sex-adjusted associations between BLL reached statistical significance for only 1 of the 6 self-reported offending outcomes at age 15 years.”
Researchers said that the links they found between BLL and criminal offending were weak at best, and that there seemed to be no dose-response relationship. That finding is contrary to some past research, they noted.
The study concluded that children still need to be protected from lead exposure, but purely for health reasons.
“This finding does not negate the evidence of the detrimental health effects of lead,” the researchers concluded. “At-risk children should continue to be tested for lead, and efforts to reduce lead exposure should continue.”
Childhood lead poisoning is considered the most preventable environmental disease among young children. More than half a million children in the U.S, have lead blood levels above 5 micrograms per deciliter, the “level of concern” reference set by the CDC.
Sources of lead exposure include lead-based paint, which was used in homes constructed through 1978, lead naturally occurring in soil, renovation repairs, old plumbing, old playground equipment, water, industrial pollution, and household dust contaminated from other exposures.
Although lead paint has been banned in the U.S., many homes nationwide still have the toxic paint, and as they age there is a continuing risk that the paint may chip or flake off of the walls, which poses a serious risk of lead poisoning for young children who ingest the paint chips. Many of those homes are in economically depressed urban areas with high crime rates.