The report, published Tuesday in the journal JAMA Pediatrics, should ease the minds of parents in areas where children have been exposed to high levels of lead in their drinking water.
After adjusting for socioeconomic status, a team of researchers found a weak connection between childhood lead exposure and subsequent criminal offenses. Lead exposure was also not associated with recidivism or violence, according to the study.
“Childhood lead exposure has been associated with abnormalities in brain structures, such as the hippocampus and cerebral cortex, and with disrupted neuronal development, myelination, and neurochemical processing,” the authors write. “Lead exposure has also been associated with childhood behavioral problems and lasting declines in intelligence.
“One hypothesized behavioral effect of high levels of lead exposure is increased antisocial and criminal behavior.”
To test this theory, the team monitored 553 people born in New Zealand between 1972 and 1973 for more than three decades.
After measuring the participants’ blood lead levels (BLL) when they were 11, the team tracked the group’s self-reported criminal offending up to age 38.
In the end, 154 participants were convicted of at least one crime. Slightly more than half – 86 – were convicted more than once.
“The variety of self-reported offenses was weakly associated with BLL and only reached statistical significance at ages 15, 18, and 26 years,” the study reads. “After controlling for sex, the association between higher BLL and variety of self-reported offenses remained weak and was statistically significant only at assessment age 15 years.”
One limitation of the study is that participants’ lead levels were measured only once, according to the team.
However, the researchers say the findings highlight the relationship between lower socioeconomic status and criminal activity, which may have affected past research.
“This study fails to support a dose-response association between BLL and criminal offending in a sample in which there was no association between BLL and childhood socioeconomic status,” the authors write. “Previously detected associations between BLL and criminal offending may be owing to the toxic effect of lead disproportionately affecting disadvantaged groups.
“Responses toward lead exposure should focus on health consequences, not potential criminal consequences.”