Researchers found that children who are exposed to lead at a young age may be more likely to be arrested later in life. Their study is the first empirical evidence of health consequences of elevated lead levels in the bloodstream.

The increased lead levels in blood, both in the pregnant mother and in the child, have been associated with criminal behavior in young adulthood.
The researchers are stunned that the lead exposure effects are still present into the later 20s. A large proportion of the population have blood levels in this neurotoxic range now in their 20s and 30s.

Childhood lead exposure has been linked to anti-social behavior, lower IQ, attention deficits disorder, hyperactivity and weak executive control functions. All of these disorders represent risk factors for future delinquent behavior, especially attention-deficit hyperactivity disorder, which is a risk factor for adult criminal behavior. Sales of leaded gasoline or high atmospheric lead levels have also been associated with criminal behavior.

In the past, lead was widely used in paint, solder for water pipes and gasoline but its use has been curtailed recently. The U.S. government banned lead paint and solder that resulted in a dramatic decrease in the number of U.S. children with increased blood lead levels.

However, many older buildings still have lead paint on the walls and windowsills.

In the study, researchers looked at maternal blood lead concentrations in their pregnancies as well as concentrations in 250 children at regular intervals until they were almost 7 and then correlated them with arrest and incarceration information taken from county records years later on.
Arrest rates were found to get 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 offenses by more than 25%.
Another study showed that used MRI data showed that exposure to lead during childhood had reduced gray matter volume in the brain in adulthood. The reductions correlated to the regions responsible for executive function, mood regulation and decision-making. The reductions were more striking in males than in females.

These studies are shedding new light that no dose is safe for lead and although lead has been largely removed from the landscapes of developed countries, the same is not necessarily true in other parts of the world.

Even in the United States, more should be done, researchers said. About 60 % of children on Medicaid are not being screened [for lead exposure, as they should be and 40% of children with blood levels in the neurotoxic range were never followed up.