Key Takeaways:
- A study explored the mental health effects of lead exposure from gasoline over the past 75 years in the U.S.
- Researchers found that lead exposure has a larger impact on mental health than previously realized.
- Childhood exposure to leaded gasoline has been linked to hundreds of millions of psychiatric disorders in the U.S., according to a recent study in Journal of Child Psychology and Psychiatry.
The study’s findings suggest that lead has played a larger role in mental health issues than previously understood, said Aaron Reuben, PhD, a postdoctoral scholar in neuropsychology at Duke University.
Study Overview:
Reuben and colleagues focused on the significant mental health effects of lead exposure, particularly from car exhaust containing leaded gasoline, which was used in the U.S. until its ban in 1996. Lead exposure in industrialized nations peaked between 1960 and 1990, with around 170 million Americans, particularly children, exposed to dangerous levels of leaded gasoline. Many children were exposed to levels that were three to six times higher than the current reference value for lead.
Lead exposure during childhood has been shown to disrupt brain development, affecting cognitive abilities, fine motor skills, and emotional regulation. This has been associated with various mental health conditions, including depression, anxiety, and hyperactivity.
Methods and Findings:
The researchers analyzed National Health and Nutrition Examination Survey data alongside historical data on leaded gasoline use to track childhood blood-lead levels from 1940 to 2015. They estimated the impact of lead exposure on mental health, specifically looking at five outcomes: general psychopathology, IQ scores, internalizing disorders (e.g., depression, anxiety), ADHD, and personality trait differences.
Reuben and colleagues found that childhood exposure to leaded gasoline contributed to 602 million “General Psychopathology points” in the U.S. population by 2015, reflecting an increase in mental illness liability. This exposure also resulted in approximately 151 million excess mental disorders, with significant increases in symptoms of internalizing disorders (0.64 standard deviations), ADHD (0.42), and neuroticism (0.14). The effects were particularly strong for those born between 1966 and 1986.
Ongoing Concerns:
Although leaded gasoline was banned in the U.S., Reuben highlighted that lead exposure remains a serious concern. Many Americans, especially children, have been exposed to lead levels far exceeding natural background levels. He pointed out that approximately 500,000 children in the U.S. have elevated lead levels each year, primarily due to lead in old paint and contaminated soil in older homes.
Reuben emphasized that global efforts to eliminate lead exposure should be a priority, urging the removal of lead from products like fuel and paint, which still pose risks to families today.
Conclusion:
This study underscores the lasting impact of lead exposure on mental health in the U.S., particularly in individuals exposed during childhood. Despite the ban on leaded gasoline, exposure to lead remains a significant public health issue, with implications for both mental and physical health.
