Harmful exposure to lead from air, water, and soil affects the well-being of 151 million Americans. In 1923, lead was added to gasoline to improve automobile engine performance. However, this push for vehicle health has come at a significant cost to human well-being.

A new study estimates that childhood exposure to lead-laden car exhaust fumes is altering the mental health balance of the U.S. population, making generations of Americans more depressed, anxious, inattentive or hyperactive. One study estimates that 151 million cases of mental disorders have occurred as a result of lead exposure in American children over the past 75 years.

Duke University neuropsychologist Ph.D. Findings by Aaron Reuben and his colleagues at Florida State University suggest that Americans born before 1996 have significantly more mental health problems due to lead exposure and are more likely to experience changes in their personality. This will make them less successful and resilient in life.

CNG was banned in the United States in 1996, but researchers say anyone born before then was exposed to extremely high rates of lead during childhood, especially during the 1960s and 1970s, when its use peaked. The team’s paper was recently published. Journal of Child Psychology and Psychiatry.

Lead toxicity and long-term consequences

Lead is neurotoxic and can destroy brain cells and alter brain function when ingested. That’s why there is no safe level of exposure at any stage of life, health experts say. Young children are particularly vulnerable to lead’s ability to disrupt brain development and alter brain health. Unfortunately, no matter our age, our brains are not equipped to ward off lead poisoning.

Because water systems in older American cities still contain lead pipes, the EPA issued rules in October giving cities 10 years and $2.6 billion to identify and replace lead plumbing. Earlier this year, the EPA also lowered the level of lead in soil it believed was potentially hazardous, leaving about 1 in 4 U.S. households with soil that may need cleanup.

“Humans are not adapted to being exposed to lead at the levels we were exposed to in the last century,” Reuben said. “We have few effective measures to deal with lead once it enters the body, and most of us are exposed to lead at 1,000 to 10,000 times the natural level.”

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

To answer the difficult question of how more than 75 years of leaded gas use can leave a lasting mark on human psychology, Reuben and his co-authors Michael McFarland and Matthew Hauer, both professors of sociology at Florida State University, answered the question publicly across the country. data.

Using historical data on blood lead levels of U.S. children, lead gas use, and population statistics, they determined the estimated lifetime burden of lead exposure for every American alive in 2015. Based on this data, they evaluated the effects of lead on mental health and personality. By calculating “mental illness scores” from exposure to lead gas as an indicator of its harmful effects on public health.

“This is exactly the same approach we have used in the past to estimate the damage lead does to the cognitive ability and IQ of the population,” McFarland said, noting that the research team had previously found that lead stole 824 million IQ points from the U.S. population over the last century. .

Common psychological consequences

“We have seen very significant changes in the mental health of generations of Americans,” Hauer said. “This means many more people are experiencing mental health problems than would be the case if we never added lead to gasoline.” Lead exposure led to more mental disorders, such as depression and anxiety, but also led to more people experiencing milder distress that impaired their quality of life.

“For most people, exposure to lead would be like a low-grade fever,” Reuben said. “You don’t go to the hospital or get treatment, but you do struggle a little bit more than if you didn’t have a fever.”

Lead’s effects on brain health are also linked to changes in personality occurring nationally. “We are assessing population-level change in neuroticism and conscientiousness,” McFarland said.

As of 2015, more than 170 million Americans (more than half of the US population) had clinically concerning blood lead levels in childhood; This condition likely causes lower IQs and greater mental health problems, possibly predisposing them to increased risk. for other long-term health disorders such as cardiovascular diseases.

Consumption of leaded gasoline increased rapidly in the early 1960s and peaked in the 1970s. As a result, Ruben and his colleagues found that almost everyone born in those two decades was almost certainly exposed to harmful levels of lead from car exhaust. Generation X (1965-1980), the generation most exposed to lead, will experience the greatest mental health losses.

“We are beginning to understand that lead exposure in the past, even decades ago, can impact our health today,” Ruben said. “Our job will be to better understand the role lead plays in our nation’s health and make sure we protect today’s children from new lead exposures, wherever they occur.”