Exposure to lead as a child has been linked with criminal behavior as an adult, according to a study released on May 29, 2008 in the open access journal PLoS Medicine.

Lead poisoning is toxic to the nervous system, and exposure in childhood has been proposed as a potential risk factor for antisocial behavior in adulthood. However, until now this has only been weakly substantiated by indirect measurement of childhood lead exposure in adults, or by direct measurement of lead but without following subjects into adulthood.

To examine this proposition while eliminating these limitations, Dr Kim Dietrich and colleagues (University of Cincinnati, USA) investigated the association of lead paint exposure, both in early childhood and in the uterus, and criminal arrests in adulthood in poor areas of Cincinnati, which tend to have more housing with lead paint chips. Beginning in 1979 and extending into 1984, the group enrolled pregnant women in these areas. Out of the 376 newborns recruited into the study, 250 were actually included in the final analysis.

In order to quantify their exposure to lead, the scientists measured blood lead levels during pregnancy, and regularly afterwards until the children were six and half years old. Subsequently, the level of exposure was then compared to how many times each of these descendents had been arrested between turning 18 years old and the end of October 2005, according to the criminal justice records.

Increased blood levels before birth and into early childhood were associated with higher rates of arrest, both for violent crimes and for any reason. For instance, every 5 ug/dL increase in blood levels at the age of six led to almost a 50% increase in risk (1.48) of being arrested for a violent crime.

There are many limitations to the study that were recognized by the authors. These include an inability to monitor all criminal behavior, because most criminal behavior does not lead to arrest. Additionlly, they were unable to assess the IQ of the subjects, which is relevant because lead exposure can impair intelligence, which in turn can increase the likelyhood that a criminal offender will actually be arrested.

However, according to the authors, the studying findings are significant despite these limitations, and they implicate early exposure to lead as a risk factor for behaviors that result in criminal arrest. Environmental lead levels have dropped in the US in the last 30 years, as have crime rates, but neither of these drops has been uniform, and inner-city children remain especially vulnerable to lead exposure. Therefore, they suggest, reducing childhood lead exposure could be an important and pragmatic method of reducing violent crime.

Dr David Bellinger (Harvard Medical School, Boston, USA) contributed an accompanying commentary on this study, in which he says that even if the actual contribution of lead poisoning to criminal risk is small, it is important because it has the potential for erradication, because we know how to prevent it. He notes that, while a detrimental effect on IQ is the most commonly studied aspect of lead poisoning, this is only a small piece of the harms caused by childhood lead exposure.


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

Neurological and behavioral consequences of childhood lead exposure.
Bellinger DC
PLoS Med 5(5): e115.
Click Here For Full Length Perspective

Anna Sophia McKenney