Lead Exposure From Petrol Linked To Mental Health Disorders Among Americans

A new study published in the Journal of Child Psychology and Psychiatry has revealed a shocking connection between leaded petrol and the rise in mental health disorders in the U.S. It’s estimated that lead exposure has contributed to an additional 151 million cases of anxiety, depression, ADHD, and neuroticism among Americans born in the late 20th century. While the phase-out of leaded petrol began decades ago, the toxic legacy of lead may continue to impact public health worldwide

For millennia, lead has been used in various everyday products, from Roman wine sweeteners to modern petrol additives. However, a new study published in the Journal of Child Psychology and Psychiatry has revealed a disturbing link between leaded petrol and a significant increase in mental health disorders in the United States.

The research suggests that the widespread use of leaded petrol has contributed to an additional 151 million mental health disorders in Americans, particularly those born between 1966 and 1986 (Generation X). The study identifies a rise in anxiety, depression, attention deficit hyperactivity disorder (ADHD), and neuroticism, alongside a decrease in conscientiousness.

Lead exposure has long been known to have toxic effects on human health. However, the full extent of these effects and the exposure levels at which they manifest continue to be explored. Tetraethyl lead, a compound added to petrol in 1921, was initially hailed for improving engine performance by reducing "knocking" in car engines. Despite early reports of illness among workers and concerns about the dangers of lead exposure, these warnings were largely dismissed at the time by the US Surgeon General and industry-backed studies.

By the 1970s, however, growing evidence of lead’s harm to human health prompted the phase-out of leaded petrol, starting with the invention of the catalytic converter. Leaded paint was also banned for residential use in 1978. In the UK, leaded petrol was banned in 1999, with Algeria being the last country to prohibit its use in 2021.

As lead gradually phased out of the environment, research has begun to highlight its lingering effects, especially on children exposed to leaded petrol. Studies have shown that this exposure can reduce educational outcomes, increase the likelihood of criminal behavior, and decrease lifetime earnings. Notably, studies from both Sweden and the US have shown a correlation between lead exposure and these negative outcomes.

Lead’s toxicity is multifaceted, impacting cognitive function, cardiovascular health, kidney function, and even fertility. Studies have also shown that people living near Nascar circuits during races experienced higher rates of cardiovascular disease, correlating with ongoing exposure to lead from racing fuels.

The new study provides a first estimate of the mental health impacts of leaded petrol on American society. While the research indicates that lead exposure has played a significant role in mental health disorders, it is likely that its broader impact, including other forms of lead exposure, is even greater. Despite the ban on leaded petrol, lead particles from past emissions can still be found on streets, particularly in cities like London, suggesting that lead may continue to contribute to public health challenges today.

(The writer is an Associate Professor in the Department of Economics at the University of Warwick)