Childhood lead exposure is a risk factor for criminal behavior

Lead exposure during childhood is associated with adult criminal behaviour, including violent crime, revealed by researchers in this week’s PLoS Medicine. Childhood lead exposure is a purported risk factor for antisocial behavior, but prior studies either relied on indirect measures of exposure or did not follow participants into adulthood to examine the relationship between lead exposure and criminal activity in young adults.

Dr Kim Dietrich and colleagues (University of Cincinnati, USA) studied the association between exposure to lead in the uterus and during early childhood and criminal arrests in adulthood, in poor areas of Cincinnati.

Lead is known to be toxic to the nervous system. Childhood exposure has been identified as a potential risk factor for antisocial behaviour in adulthood. But this link has relied on indirect measurement of childhood lead exposure in adults or has measured childhood lead exposure directly but has not followed lead-exposed children into adulthood. The new study overcomes both of these limitations.

Between 1979 and 1984, the researchers recruited pregnant women living in poor areas of Cincinnati, which had a high concentration of older lead-contaminated housing. Out of the 376 newborns recruited into the study, 250 were included in the final analysis. Blood lead levels were measured during pregnancy and then regularly until the children were six and a half years old, as an indication of their lead exposure. This exposure was then correlated with local criminal justice records on how many times each of the 250 offspring had been arrested between becoming 18 years old and the end of October 2005.

The researchers found that increased blood lead levels before birth and during early childhood were associated with higher rates of arrest for any reason and for violent crimes. The authors discuss a number of limitations in their study including not being able to capture all criminal behavior (since most criminal behavior does not lead to arrest) and being unable to assess IQ (lead exposure impairs intelligence, which in turn makes it more likely that a criminal offender will be arrested).

These findings provide strong evidence that early lead exposure is a risk factor for criminal behavior, including violent crime, in adulthood. The findings therefore suggest that a further reduction in childhood lead exposure might be an important and achievable way to reduce violent crime.

Wright JP, Dietrich KN, Ris MD, Hornung RW, Wessel SD, et al. (2008) Association of prenatal and childhood blood lead concentrations with criminal arrests in early adulthood. PLoS Med 5(5): e101.

Source: PLoS Medicine, USA

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