Lead exposure linked to criminal behaviour

Exposure to lead at a young age is associated with criminal behaviour in young adulthood. Previous studies have linked childhood lead exposure to anti-social behaviour; lower IQ, attention deficits, hyperactivity and weak executive control functions, all of which are risk factors for adult criminal behaviour. Studies have also related sales of leaded gasoline or high atmospheric lead levels with criminal behaviour. To determine if prenatal and childhood blood lead concentrations are associated with arrests for criminal offences, American researchers studied 250 individuals, aged between 19 and 24 years. Prenatal maternal blood lead concentrations were measured during the first or early second trimester of pregnancy. Childhood blood lead concentrations were measured on a quarterly and biannual basis through 6.5 years. Total arrests and arrests for offences involving violence were collected from official criminal records registered against the participants. Arrest rates were found to be higher as blood lead concentrations went up. The association between high blood lead levels and violent crimes was even stronger. Any 5 micrograms per deciliter elevation in blood lead levels increased the rate of arrest for violent offences by more than 25 percent. Exposure to lead during childhood was associated with reductions in gray matter volume in the brain in adulthood. The reductions were related to specific regions, including those responsible for executive function, mood regulation and decision-making. The reductions were more striking in males than females. These findings provide strong evidence that early lead exposure is a risk factor for criminal behaviour, including violent crime, in adulthood. The researchers noted that a reduction in childhood lead exposure might be an important and achievable way to reduce violent crime.

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