Sucking on a silvery chunk of lead when you’re a kid can, decades later, cause you to be mean and self-centered.
While it might sound like a prophecy from a witch, this bizarre fact was the primary finding of a massive University of Texas study examining the effects of lead exposure on people’s personalities.
The study, published last week in the Proceedings of the National Academy of Sciences, investigated the impact of lead on more than 1.5 million people in the United States and Europe. It found that lead exposure was linked to being less agreeable and less considerate as well as other personality issues.
Though people today have much less exposure to lead than in the past, thousands are found to have unsafe blood lead levels every year in Texas. The study highlights just how pernicious this metal can be, even at low levels.
Ted Schwaba, a postdoctoral researcher in the psychology department at University of Texas, was the lead author of the study. He said that though we’ve known for decades that lead can stunt our cognition and even result in increases in crime, his study was the first to find that people all over the world experience personality problems as a direct result of exposure to lead.
“It’s not just, ‘Hey, if I had some lead exposure, I might be more likely to drop out of school,’ ” he said. Instead, when lead gets into our bodies it seems to affect who we are at our core and how we interact in the world.
The United States has made huge strides in reducing the prevalence of lead over the past 50 years, but recent events in Flint, Michigan, and elsewhere demonstrate that lead poisoning is still a pressing modern concern.
According to the Texas Department of State Health Services, more than 4,000 Texas children had elevated blood lead levels in 2019, the most recent year data was available. And that’s only counting the 13% of children who were tested in the state.
The lead concentrations in these children are low by historical standards, according to the national Centers for Disease Control and Prevention, but there is no safe level of exposure to lead, which, like cobra venom, is a potent neurotoxin.
While adults are susceptible to lead poisoning, too, toddlers are at higher risk — in part because they frequently put objects from their environment into their mouths. This can be a particular problem in homes with lead paint that chips and flakes.
“That’s particularly bad for children in older housing because lead paint chips are sweet,” said Fatima Frausto, a member of the Blood Lead Surveillance Branch of the Texas Department of State Health Services. “They pick it up; they put it in their mouth; they like it; they eat more of it.”
Frausto said other potential sources of exposure in Texas include older lead pipes used to carry drinking water, as well as jewelry, lead residue at industrial sites and even certain spices.
In Texas, Austinites have a lower risk of lead exposure from water pipes than people living in older cities because much of the piping infrastructure in Austin was built after the use of lead was phased out starting a half-century ago.
Matt Cullen, division manager of distribution system engineering with Austin Water, said his team is conducting a full inventory of where lead exists in the system. They have found a few lead pipes, but all have been replaced.
“In Austin, very rarely do we see lead in customers’ water,” he said. “Austin was progressive in eliminating lead as a material to be used much ahead of the rest of the country and proactive in removing it when found.”
Still, more than 150 children in Travis County were found with elevated blood lead levels in 2019, the most recent year with available data, and that lead comes from somewhere.
Studies have shown that lead concentrations are highest in lower-income communities that are disproportionately situated near industrial sites. Earlier this year, an illegal dumping site with elevated lead levels in a mostly Black and Latino neighborhood in South Dallas called Shingle Mountain was finally cleaned up.
Schwaba said he hopes one of the effects of his research will be to bring attention to the disproportionate impact lead has on certain communities.
“Every time people look at how bad it is, they find it’s worse and worse,” he said. Yet “there’s still a lot of lead in the soil and lead in pipes, and it’s still exposing pockets of people to huge amounts of lead.”
For his study, Schwaba and his team used data from an online personality quiz taken by millions of people. They then matched each person’s personality profile from the quiz to data about their lead exposure based on where they grew up as a child. For their study, they selected a sample of responses from 269 counties in the United States and 37 European countries.
They found that people from areas with higher lead exposure had more negative personality profiles. Specifically, they were less agreeable and conscientious, and sometimes more neurotic.
The research team then examined how the personality profiles shifted as different U.S. counties began limiting exposure to lead starting in the 1970s, largely as a result of the Clean Air Act’s regulations on leaded gasoline. They found that people born after lead levels started to decline in the county where they grew up had healthier and more mature personalities as adults, as recorded by the personality quiz.
Because different counties in the U.S. stopped using leaded gasoline at different times between 1970 and the early ’90s, the personality differences observed by this study can’t simply be because of a particular generation being “nicer” or “meaner,” Schwaba explained. The researchers also controlled for participants’ income and age.
Schwaba estimated that the societal costs of more negative personality traits can derive from people who are anxious or less conscientious and thus have higher health care expenses.
While the personality differences were small for most people, Schwaba said they can still have an impact.
“If I’m just a little bit friendlier, that’s probably tens of arguments I’ve missed over my life, maybe one or two extra friends that I have, one relative who likes me a little bit more,” he said.
More info on lead and testing of children
If you think you or your child has been exposed to lead or you want more information on limiting your exposure to lead, you can call the Blood Lead Surveillance Group at 800-588-1248.