A history of lead in gasoline may be behind tens of millions of mental health conditions in the United States, according to a new research.
The study published Wednesday, December 4, in The Journal of Child Psychology and Psychiatry estimates that about 151 million mental disorder diagnoses in the US are attributable to lead. The exposure likely would not have happened had lead not been in gasoline,
“We’ve shifted the curve in the population for mental health problems, so that everyone has a greater liability in the mental illness symptoms, and that some people who were already at risk are going to develop diagnosable disorders sooner, more often or more kinds,” said co-author of the study Dr. Aaron Reuben, assistant professor of clinical neuropsychology at the University of Virginia.
Cars ran on gasoline containing lead starting in the 1920s, and the US did not start phasing out the substance until the 1980s, after substantial evidence of harm over the decades, according to the US Energy Information Administration.
But in the world today gasoline with lead continues to fuel some planes, race cars, and farm and marine equipment.
“The people who were exposed are not in the history books,” Reuben said. “Millions of Americans are walking around with an unknown, invisible history of lead exposure that has likely influenced for the worse how they think, feel and behave.”
Scientists have accumulated research over the last century showing that lead is harmful to almost every organ system, Reuben said.
In a previous study, he and a team used data on childhood blood-lead levels, leaded gas use, and population statistics to estimate childhood lead exposure and found that half of the US population were exposed to adverse levels of lead early in life.
The number of people impacted might be unexpected to many people, said Dr. Bruce Lanphear, a population health scientist at Simon Fraser University in Canada with expertise in lead poisoning. He was not involved in the research.
“Given their caveats and limitations, I think they’ve done a thorough job of trying to estimate exposures,” he said.
One such limitation was that researchers did not measure all possible exposure sources, meaning that the results may actually underestimate the problem, Lanphear added.
“We have not been able to fully understand how those exposures influenced health and disease across the century,” Reuben added.
Lead is a potent neurotoxin and can disrupt brain development in many ways that can impact most types of mental health problems, including anxiety, depression and ADHD, he said. But people were also likely impacted in ways that cannot be diagnosed.
“It also changed personalities. We believe that (lead exposure) makes people a little less conscientious –– so less well organized, less detail-oriented, less likely to be able to pursue their goals in an organized way, and more neurotic,” Reuben added.