Decades of lead exposure from car exhaust during the 20th century have profoundly impacted the mental health of millions of Americans, a new study revealed on Wednesday.
Researchers estimated that toxic lead from gasoline used widely before its ban in 1996, contributed to 151 million cases of mental health disorders, including depression, anxiety, and attention deficit hyperactivity disorder (ADHD).
"Humans are not adapted to be exposed to lead at the levels we have been exposed to over the past century," said Aaron Reuben, a neuropsychologist at Duke University in North Carolina, US.
"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," he explained in a university press release.
The study, published in the Journal of Child Psychology and Psychiatry, used historical blood-lead data, gasoline usage patterns, and mental health statistics to assess lead's lasting effects.
It follows earlier research indicating lead exposure cost the US population 824 million IQ points over the past century.
"Generation X, born between 1965 and 1980, experienced the greatest lead exposure and the most severe mental health losses," noted Mathew Hauer, a sociologist at Florida State University.
Reuben also emphasized that lead's toxic effects extend beyond full-blown psychiatric conditions, often causing subtle but widespread declines in quality of life.
"Our job moving forward will be to better understand the role lead has played in the health of our country and to make sure we protect today's children from new lead exposures wherever they occur," he said.
According to the World Health Organization (WHO), lead exposure was attributed to more than 1.5 million deaths globally in 2021, primarily due to cardiovascular effects.
WHO identifies lead as one of 10 chemicals of major public health concern requiring action by member states to protect the health of workers, children, and women of reproductive age.
