A new study reveals that childhood exposure to leaded gasoline between 1960 and 1990 has left a lasting imprint on America’s mental health, potentially contributing to 151 million excess cases of mental disorders over the past 75 years.
The findings suggest this environmental exposure may have fundamentally altered the psychological landscape for an entire generation.
Published in Journal of Child Psychology and Psychiatry | Estimated reading time: 4 minutes
In 1923, lead was first added to gasoline to help keep car engines healthy. That decision, while beneficial for automobiles, has cast a long shadow over human well-being. Now, researchers have calculated the profound mental health impact of this widespread environmental exposure, particularly on those born during its peak use.
The research team, led by Aaron Reuben, a postdoctoral scholar in neuropsychology at Duke University, along with colleagues at Florida State University, combined historical data on childhood blood-lead levels with leaded gasoline consumption patterns to assess the exposure’s psychological impact. Their findings paint a concerning picture of how this environmental toxin has shaped American mental health.
“Humans are not adapted to be exposed to lead at the levels we have been exposed to over the past century,” notes Reuben. “We have very few effective measures for dealing with lead once it is in the body, and many of us have been exposed to levels 1,000 to 10,000 times more than what is natural.”
The study found that lead exposure led to measurable changes in mental health and personality traits across the population. Those born between 1966 and 1986—Generation X—were most affected, having been exposed during peak leaded gasoline use. The researchers calculated that lead exposure increased population-level symptoms of anxiety and depression by 64%, attention-deficit/hyperactivity disorder symptoms by 42%, and altered key personality traits including conscientiousness and neuroticism.
The impact extends beyond diagnosed conditions. As Reuben explains, “For most people, the impact of lead would have been like a low-grade fever. You wouldn’t go to the hospital or seek treatment, but you would struggle just a bit more than if you didn’t have the fever.”
Glossary
- Blood-Lead Levels (BLL): The amount of lead present in blood, used to measure exposure to environmental lead.
- Neurotoxin: A substance that damages or destroys nerve tissue, affecting brain function and development.
- Neuroticism: A personality trait characterized by tendency toward anxiety, depression, and emotional instability.
- Conscientiousness: A personality trait reflecting organization, responsibility, and goal-directed behavior.
Test Your Knowledge
When was lead first added to gasoline in the United States?
Lead was first added to gasoline in 1923.
Which generation was most affected by lead exposure from gasoline?
Generation X, those born between 1966 and 1986, experienced the greatest exposure during the peak use of leaded gasoline.
By what percentage did lead exposure increase population-level symptoms of anxiety and depression?
The study found a 64% (0.64-standard-deviation) increase in population-level internalizing symptoms (anxiety and depression).
How many excess mental disorders are estimated to be attributable to lead exposure in the US population?
The researchers estimate 151 million excess mental disorders attributable to lead exposure over the past 75 years.
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