Lead Exposure During Childhood Creates Less Agreeable Adults: Study

How can lead exposure during childhood affect people's lives down the line? A team of researchers found that such exposures may actually result in less healthy personalities in adulthood.

Exposure to lead in childhood can have "devastating lifelong consequences," the researchers said in a new study published in the Proceedings of the National Academy of Sciences.

For instance, children who are exposed to lead tend to have lower IQs and engage in delinquent behavior. They're also more likely to drop out of school, according to the study.

The researchers found that such exposures can also have problematic effects on people's personalities. It turns out, those who were exposed to lead as children are more likely to have less mature and less healthy personalities during adulthood, the University of Texas at Austin (UT Austin) said in a news release.

For their study, the researchers looked at the personality questionnaire results from 1.5 million people in 256 counties in the U.S. and 37 European nations.

For the U.S., the experts linked the participants' personality questionnaire data to their atmospheric lead exposure based on the historical atmospheric lead data logged by the Environmental Protection Agency (EPA) since 1960.

"Adjusting for age and socioeconomic status, U.S. adults who grew up in counties with higher atmospheric lead levels had less adaptive personality profiles: they were less agreeable and conscientious and, among younger participants, more neurotic," the researchers wrote.

"These three traits — conscientiousness, agreeableness and low neuroticism — make up a large part of what we would consider a mature, psychologically healthy personality and are strong predictors of our success or failure in relationships and at work," study co-author Ted Schwaba of UT Austin, said as per the university news release.

"Normally, across the lifespan, people become more conscientious and agreeable, and less neurotic."

The researchers then compared the personality profiles of those who were born before and after the removal of leaded gasoline because of the 1970 Clean Air Act. Sure enough, they found that those who were born when lead levels were beginning to decline in their county had "more mature, psychologically healthy adult personalities."

The researchers still went further to see if the results were simply a result of "shared historical or social experiences," UT Austin said. So they replicated the study in data from the European nations, where lead was banned later as compared to the U.S. Again, the researchers found that those who spent their childhood in places where there was more atmospheric lead also had "less agreeable, more neurotic" personalities when they became adults.

According to the researchers, this shows that reducing lead exposure further is a "critical public health issue."

"For a long time, we've known lead exposure is harmful, but each new wave of research seems to identify new ways in which lead exposure harms society," Schwaba said. "Though there's much less lead in the atmosphere today, lead remains in pipes, the topsoil and groundwater. And these sources of lead exposure tend to disproportionately harm people of color — Black children are twice as likely to have high levels of lead in their blood as white children."

In the end, the researchers added that further restrictions on lead emissions "are needed to maximize human flourishing."