A new study estimates that childhood exposure to lead from gasoline has contributed to millions of excess psychiatric disorders in the past 75 years.
Although leaded gasoline was banned in 1996, its impact continues to be felt. Published in the Journal of Child Psychology and Psychiatry on Wednesday, the study analyzed childhood blood lead levels in the U.S. between 1940 and 2015. Researchers concluded that exposure to lead from car exhaust during early development led to approximately 151 million additional cases of mental health disorders nationwide.
The study highlights how lead exposure affected generations of Americans, increasing rates of depression, anxiety, inattention, and hyperactivity.
Researchers from Duke University, Florida State University and the Medical University of South Carolina found that lead exposure not only increases mental disorders, but likewise reduces impulse control and accentuates the tendency toward neuroticism.
The study revealed that the mental health and personality effects of lead exposure used to be most pronounced among people born between 1966 and 1986. Generation X, particularly those born between 1966 and 1970, endured the heaviest burden of lead-related mental health disorders. This period in particular coincides with the peak of leaded gasoline use between the mid-1960s and mid-1970s.
“Those born during that period can’t go back and change their exposure,” said Aaron Reuben, a co-author of the study and a postdoctoral scholar in neuropsychology at Duke University and the Medical University of South Carolina.
He added that, “Studies like ours today add more evidence that removing lead from our environment and not putting it there in the first place has more benefits than we previously understood.”
Although lead is no longer used in gasoline, it can still be found in other sources, such as certain imported toys, outdated water service lines, contaminated soil, and paint in older homes.
The Centers for Disease Control and Prevention (CDC) emphasizes that no level of lead exposure is safe. Even minimal exposure can lead to developmental and learning difficulties, as lead is known to damage the brain, nervous system, and reproductive system.
Furthermore, the study published Wednesday integrated data on blood lead levels and historical exposure estimates with findings from previous research, including a 2019 study that tracked nearly 600 New Zealanders. This earlier study followed children exposed to lead and assessed their mental health over a span of more than three decades.
Reuben also explained that the new research does not introduce fresh evidence about lead’s harmful effects or claim to prove causation. “We’re simply applying existing evidence to the entire U.S. population,” he said.
He added, “We are not at all concerned that we may have overestimated the harm.”
Dr. Lisa Fortuna, chair of the American Psychiatric Association’s Council on Children, Adolescents, and Their Families, commended the study, noting that it should not cause panic.
“The research shed some light on the profound and lasting impact of environmental factors,” Fortuna stated.
Reuben emphasized that prevention is the most effective way to protect people.
“We’ve done a lot of good in the U.S. reducing lead exposures. Blood lead levels have gone way down, but they could go down further,” he said.
