A new study has found a link between childhood exposure to lead from gasoline and increased rates of mental illness and personality changes, according to research published Dec. 4 in the Journal of Child Psychology and Psychiatry.
According to the study, which analyzed the effects of leaded gasoline use from 1960 to 1990 in the United States, researchers estimate that there were 151 million excess mental disorders by 2015, which could be linked to lead exposure. That figure is nearly half of the nation’s population. The impact was most prevalent for those born between 1966 and 1986, known as Generation X.
The study’s corresponding author, Michael McFarland of Florida State University, said society has historically put profits before environmental concerns, despite safer alternatives available, in a press release the same day.
“Society frequently operates under the presumption that environmental exposures are safe until proven otherwise. Leaded gasoline wasn’t needed as an anti-knock agent—there were alternatives available. It was profitable. An abundance of incontrovertible evidence occurring across decades was required to ban it,” he said.
McFarland said documenting the widespread effects of such exposure could help point out the flaws in such thinking and the negative health consequences that can result.
The research team used blood-lead level data from National Health and Nutrition Examination Surveys, along with historical information on the use of leaded gasoline in the United States from 1940 to 2015, to estimate the blood-lead levels of children. They then looked at mental health symptoms linked to lead exposure, according to the press release.
Researchers estimate that by 2015, the U.S. population had gained 602 million “General Psychopathology factor points” due to such lead exposure.
Researchers also examined specific health impacts and found an increase in attention-deficit/hyperactivity disorder (ADHD) symptoms for the same population studied, representing a 0.42 standard deviation increase for the population studied.
Lead exposure also appeared to affect personality traits. The study reported an increase in neuroticism and a decrease in conscientiousness among the population, representing a 0.14 standard deviation increase and a 0.20 standard deviation decrease.
In their methodology, researchers explained the findings assume a causal relationship between lead exposure and mental health outcomes, rather than just a correlation.
The study’s conclusion highlights the potential for far-reaching consequences of lead exposure, creating a “significant burden” of mental health symptoms and negative personality changes in the last 75 years, researchers state.
The Journal of Child Psychology and Psychiatry, which published this study, is recognized as a leading international journal covering child and adolescent psychology and psychiatry. It publishes empirical research, clinical studies, and reviews from various perspectives and disciplines.