Exposure to lead has been scientifically proven to cause harm and impact on children is particularly devastating. Depending on the amount and duration of exposure — children may be adversely affected. Problems can range from delayed brain and nervous system development, learning and behavioral problems, lower IQ, reduced attention span, and hearing or speech problems.
Leading hypothesis of crime
For decades, some in criminal justice, medicine, and economics believed that lead exposure contributed to juvenile delinquency and delinquency. This is called the predicate crime hypothesis. This theory is not universally accepted, although there are studies that support the link between increased aggression and lead exposure in children.
However, it is important to note that despite studies linking childhood (or early childhood) lead exposure/poisoning to later involvement in crime, experts do not conclude that lead alone is the cause of crime. Instead, it is considered a contributing factor.
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A study of lead exposure and crime
As it became clear that lead exposure was harmful, the Centers for Disease Control (CDC) adjusted its guidelines. In 1970, the guidelines were that 40 micrograms per deciliter was an acceptable amount of lead in the blood. By 2012, CDC guidelines were updated to reflect that the acceptable level was less than 5 micrograms per deciliter.
According to some economists, crime got off when lead was no longer allowed in paint or gasoline. This confluence of circumstances has led some researchers to argue that the significant drop in violent crime in the US between 1992 and 2002 was largely due to the introduction of unleaded gas.
Causes of lead exposure
The CDC now knows that no amount of lead in the blood is considered harmless. And although gas and paint no longer create lead exposures, others continue to leading sources. The most common are drinking water, dust, earth, toys, ceramics, traditional medicines and mini blinds.
Results of a 2021 survey in JAMA Pediatrics revealed that despite efforts to reduce lead exposure, nearly half a million children in the US had detectable levels of lead in their blood. Additionally, almost 2% had quantities that were elevated.
Lead recovery efforts
Stands for lead remediation (such as in Flint, Michigan) suggest that the effort would be cost-effective because less lead in drinking water would increase academic achievement, reduce mortality, and later lead to less antisocial behavior/crime. The challenge for researchers is to identify what specific impact lead exposure contributes to crime later in adolescence or early adulthood. But there seems to be recognition that it does play a role.
At the end of 2022, the first meta-analysis of predicate crime theory (including 23 studies) was completed and published. The researchers estimated that reducing lead pollution could account for a 7 to 28 percent reduction in U.S. homicide rates and up to a 20 percent convergence of urban and rural crime rates. This ground-breaking analysis concluded that lead exposure did cause an increase in crime, but was not responsible for most of the downward trend in crime seen in the late 1990s.
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Challenges to mainstream crime theory
There have always been challenges in developing a coherent, quantifiable explanation of the lead crime theory. Other factors also correlate with populations that are exposed to high amounts of lead.
Living in poverty, lack of health care, good nutrition, and educational opportunities are other factors, separate from or in combination with lead exposure.
In the US, the amount of lead in the air correlates with resource deprivation. This means that in areas where the child population is exposed to a higher concentration of lead, those children are less likely to have access to resources that would help prevent, screen, or treat lead poisoning.
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