Lead exposure in the 20th century harmed Americans’ mental health

Lead is neurotoxic and can erode brain cells and impair brain function once it enters the body. As such, there is no safe level of exposure at any point in life, health experts say. Young children are particularly vulnerable to lead’s ability to harm brain development and impair brain health. Unfortunately, regardless of our age, our brains are ill-equipped to contain lead toxicity.

Since water systems in older American cities still contain lead pipes, the The EPA issued regulations in October which give cities 10 years to identify and replace lead plumbing, and $2.6 billion to do it. Earlier this year, the EPA also lowered the level of lead in soil it considers potentially dangerous, resulting in about 1 in 4 American households having soil problems. this may require cleaning.

“Humans are not adapted to be exposed to lead at the levels we have been exposed to over the last century,” Reuben said. “We have very few effective measures to combat lead once it is present in the body, and many of us have been exposed to levels 1,000 to 10,000 times higher than naturally occurring . »

Over the past century, lead has been used in paint, pipes, solder and, most disastrously, in automobile fuel. Numerous studies have linked lead exposure to neurodevelopmental and mental health problems, particularly conduct disorders, attention-deficit/hyperactivity disorder, and depression. But until now, it was unclear how widespread the symptoms of lead-related mental illness would have been.

To answer the complex question of how the use of lead gas for more than 75 years may have left a permanent mark on human psychology, Reuben and his co-authors Michael McFarland And Matthew Hauerboth professors of sociology at Florida State University, turned to publicly available national data.

Use historical data about the United States blood lead in children, use of leaded gasAnd demographic statisticsThey determined the likely burden of lead exposure over the lifetime of every American living in 2015. From this data, they estimated the assault of lead on mental health and personality by calculating the ” mental illness points” gained from exposure to lead gas as an indicator of its harmful impact. on public health.

“This is exactly the approach we have taken in the past to estimate the harms of lead on population cognitive abilities and IQ,” McFarland said, noting that the research team had previously identified that lead stole 824 million IQ points of the American population over the last century.

“We’ve seen very significant changes in mental health across generations of Americans,” Hauer said. “This means that many more people suffered from psychiatric problems than if we had never added lead to gasoline. » Lead exposure resulted in higher rates of diagnosable mental disorders, such as depression and anxiety, but also higher rates of individuals experiencing milder distress that could harm their quality of life.

“For most people, the impact of lead would have been like a mild fever,” Reuben said. “You wouldn’t go to the hospital or seek treatment, but you would just have a little more trouble than if you didn’t have a fever. »

Lead’s effect on brain health has also been linked to personality changes that manifest nationally. “We estimate a change in neuroticism and conscientiousness at the population level,” McFarland said.

In 2015, more than 170 million Americans, more than half the U.S. population, had clinically concerning blood lead levels as children, likely leading to lower IQ and more problems with mental health, and probably put them in a difficult situation. a higher risk of other long-term health problems, such as an increase in cardiovascular disease.

Consumption of leaded gasoline increased rapidly in the early 1960s and peaked in the 1970s. As a result, Reuben and his colleagues found that virtually everyone born during those two decades was almost certain to have been exposed to pernicious levels of lead from car exhaust. The generation most exposed to lead, generation X (1965-1980), would have experienced the greatest losses in mental health.

“We are beginning to understand that lead exposures from the past – even decades – can influence our health today,” Reuben said. “Our work now will be to better understand the role lead has played in our nation’s health and ensure we protect today’s children from further lead exposures, wherever they occur. »