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A groundbreaking new study has revealed that 151 million Americans suffer from mental health disorders that can be traced back to exposure to leaded gasoline, a common environmental toxin that was used in car fuel for decades. First introduced in 1923 to improve engine performance, lead in gasoline quickly became a hidden, widespread threat to public health. The effects of this exposure are now being felt across generations.
The study, led by Aaron Reuben, a postdoctoral scholar in neuropsychology at Duke University, and his team at Florida State University, shows that children exposed to car exhaust from leaded gasoline in the 20th century have faced significant mental health challenges throughout their lives. These challenges include increased rates of depression, anxiety, hyperactivity, and attention disorders. The impact has been most pronounced among those born before 1996, the year the U.S. officially banned leaded gasoline.
Reuben and his colleagues used historical data on childhood blood-lead levels, leaded-gas use, and population statistics to estimate the extent of lead’s effects on mental health. Their research suggests that Americans born before 1996, especially those born during the peak use of leaded gasoline in the 1960s and 1970s, have experienced significantly higher rates of psychiatric disorders compared to those born later.
The neurotoxic effects of lead are well-documented, with no safe threshold for exposure. Lead can damage brain cells and impair cognitive development, particularly in young children whose brains are still developing. As lead enters the body, it disrupts normal brain function, leading to long-lasting mental health and developmental problems. “We are not adapted to deal with lead exposure at the levels we’ve encountered over the past century,” Reuben said, emphasizing the lack of effective treatments once lead enters the body.
Although the U.S. banned leaded gasoline in 1996, the effects of this toxic exposure are still reverberating. The research estimates that over half of the U.S. population – more than 170 million people – had clinically concerning levels of lead in their blood as children. This exposure was most intense in the 1960s and 1970s, when leaded gasoline was at its peak. Generation X, those born between 1965 and 1980, is believed to have been the hardest hit, suffering the most significant mental health losses.
Lead exposure has long been associated with developmental and mental health issues, including attention-deficit/hyperactivity disorder (ADHD), conduct disorders, and depression. However, the scale of the mental health crisis linked to lead exposure has not been fully understood until now. Reuben and his team used a novel methodology to estimate the “mental illness points” that can be attributed to lead exposure, revealing a significant shift in mental health patterns across generations.
“We saw very significant shifts in mental health across generations of Americans,” said Michael McFarland, a sociology professor at Florida State University and co-author of the study. The research indicates that lead exposure has led to more widespread mental health problems, both diagnosable and milder issues that have still impaired the quality of life for millions of people.
In addition to mental health, lead exposure has also been linked to a decrease in IQ and an increased risk of cardiovascular diseases and other long-term health problems. Reuben’s team had previously estimated that lead exposure has stolen 824 million IQ points from the U.S. population over the last century.
As the U.S. continues to grapple with the legacy of lead exposure, the study serves as a stark reminder of the lasting impact of environmental toxins. While efforts have been made to remove lead from our environments, including replacing lead pipes and reducing lead contamination in soil, the true cost of decades of exposure is only beginning to be understood.
“The legacy of leaded gasoline is one of the most insidious environmental health crises of the 20th century,” Reuben concluded. “Our job moving forward is to better understand how lead has shaped the health of our country and to ensure that today’s children are protected from future exposure.”
The study, which appears in the Journal of Child Psychology and Psychiatry, calls for increased awareness and action to address the ongoing impact of lead and prevent future harm to children.
