Lead exposure in utero and during childhood can lead to an increased risk of criminal behavior in adulthood, according to a Milken Institute School of Public Health study released earlier this month.
The study — led by Milken graduate student and environmental health doctoral candidate Maria Jose Talayero Schettino — reviewed previous research that correlated lead exposure to increased crime and determined childhood lead exposure is linked to an uptick in criminal behavior. Talayero Schettino said policies to regulate products containing lead, like ceramic pottery, are vital in middle-income countries where lead exposure is more common, like Mexico and India.
Children, especially those under age six, are most vulnerable to lead exposure because they absorb lead more easily compared to adults since their nervous systems are still developing, according to the Centers for Disease Control and Prevention. Average lead blood levels have decreased by more than 80 percent in the United States since the 1970s due to regulations on the presence of lead in water and paint like the Lead Contamination Control Act, according to the CDC.
Talayero Schettino said lead is most often found in clay or ceramic pottery used to store food and drinks in middle-income countries. She said in Mexico, where she was born, 20 percent of children have lead poisoning and that countries with a heightened risk of lead exposure, like India and Mexico, have fewer regulations or enforcement for products containing lead compared to the U.S.
“Even though countries such as the U.S. have very strong policies to prevent lead exposure, in low- and middle-income countries, we’re not doing enough,” Talayero Schettino said. “So we need to go to the sources. We need to really pay attention to this problem and start implementing political action so that we’re not getting exposed to this.”
She said lead exposure can have neurological effects, like a lower IQ and attention and behavior disorders, as well as negative health effects like cardiovascular disease, kidney disease and reproductive problems. Talayero Schettino said behavioral disorders caused by lead exposure are associated with violence and aggression, which may result in criminal behavior.
Talayero Schettino said other researchers have determined a correlation between lead exposure and violent behavior at the population level — like research where city-wide crime dropped after officials banned lead from gasoline — but her study is the first to examine the relationship among individuals with lead exposure using previous research. She said individual-level examination allows for less biased results because the study accounts for external factors like socioeconomic status and geographical location.
“Because you’re looking at individuals, then there are more things that you can control such as socioeconomic status, poverty, status, the neighborhood they live in, maternal education, and all of these factors that may play a role in their relationship,” Talayero Schettino said.
Talayero Schettino said the varying methods of measuring lead exposure and crime in preexisting research limited her ability to accurately estimate lead’s effect on an individual’s risk for criminal behavior. She said some studies looked at the long-term presence of lead in bones while others looked at the short-term presence of lead in blood and that there was no single definition for criminal behavior, which meant she could not combine the results to estimate how big the risk for criminal behavior is.
“We encourage that more studies are needed to really understand this relationship and the strength of this relationship,” Talayero Schettino said.
Experts in criminology and psychology said any amount of lead exposure in early development can affect personality development and could cause behavior disorders and aggression, which may result in future criminal behavior.
Michael Lynch, a professor of criminology at Florida State University, said lead exposure causes an increase in violent actions and behavior because lead can damage the brain and central nervous system. He said experts associate lead exposure with an increase in spontaneous aggressive crimes — rather than premeditated crimes — because lead can cause violent and aggressive behavior.
Lynch said people in low-income neighborhoods in the United States are more vulnerable to the consequences of lead exposure because they are more likely to be exposed to older, industrial areas where traces of lead still exist due to its previous use in manufacturing.
“Lead is usually associated with violent outcomes, right? People who are exposed to lead, it’s affecting their central nervous systems,” Lynch said. “So they’re not people who were planning on stealing stuff. They’re people who act aggressively and violently.”
Ted Schwaba, an assistant professor of psychology at Michigan State University, said lead exposure can negatively impact personality development in both adults and children by shortening attention spans and increasing antisocial behavior, like getting into fights. He said while children are often thought to be more vulnerable to toxins like lead, people are constantly developing throughout their lives and lead exposure can have effects at any age.
Schwaba said though lead exposure is less common in the United States now than it was in the 1970s and before, there is a lasting prevalence of lead exposure risk in everyday items such as old pipes and plumbing systems in many cities. DC Water estimates that the District has close to 28,000 service lines with lead or galvanized iron pipes, but D.C. plans to replace them all with copper pipes by 2030.
“You see all these legacy effects everywhere in the U.S. and elsewhere, and it really seems like there’s no amount of lead exposure that’s good,” Schwaba said. “And so I don’t think there’s really any reason to stop these lead mitigation efforts, just continue to ramp them up.”
