Tens of millions of Americans born before 1996 suffered psychiatric disorders as a direct result of exposure to toxic lead.
A major review estimated that leaded car exhaust breathed before then is linked to 151 million cases of depression, anxiety and ADHD.
Older studies have also suggested that Americans exposed to these fumes have lost 824 million cumulative IQ points since 1940.
U.S. authorities banned adding lead to gasoline in 1996, but for five decades before that, Americans had been breathing fumes filled with the heavy metal.
Using national data on children’s blood lead levels and population statistics, researchers at Duke University estimated the amount of lead to which all living Americans had been exposed in 2015. They then determined the effect the Lead exposure on mental health.
Lead is known to damage the nervous system and, in turn, affects psychology. When inhaled, lead-filled smog enters the bloodstream through the lungs, where the particles are absorbed by the body, causing inflammation that can lead to the breakdown of neurons.
This can delay development, cause behavioral problems, and damage the nervous system, all of which can be related to or cause psychiatric problems.
Aaron Reuben, co-author of the study and a neuropsychology researcher at Duke University, said: “We have very few effective measures to deal with lead once it is in the body, and many of us have been exposed to levels between 1,000 and 10,000. times higher than what is natural’.
In December 2022, reality TV star Christina Hall announced on her Instagram Story that she had suffered from lead and mercury poisoning. He said he suspected her work renovating older homes, which sometimes contain lead pipes, fixtures and solder, might have made her sick. You haven’t talked about the exhaust gases.
From 1923 to 1996, lead was used in gasoline to help keep engines running smoothly. Lead use peaked in the 1960s and 1970s and was banned shortly before the beginning of the 21st century.
Mathew Hauer, a co-author of the study and a sociologist at Florida State University, said: “Many more people experienced psychiatric problems than would have if we had never added lead to gasoline.”
In 1923, people began adding lead to gasoline to help it run better in engines. It was also added to paint, welding and used to make pipes that supplied drinking water.
Since the 1980s, health authorities have taken steps to gradually eliminate the heavy metal from the products Americans depend on.
When leaded gas vaporizes, lead is released into the air, where it can be inhaled by humans or deposited on the ground.
Although special attention has been paid to the effects of lead in drinking water, the authors of the new paper, published in the journal Journal of Child Psychology and Psychiatrystated that the product that had by far the most far-reaching effects was automobile exhaust pipes.
Researchers used data from national data on blood levels in children, lead gas use over time, and general population statistics to estimate average blood lead levels for people between 1940 and 2015. .
This number gave them an idea of how much lead they were exposed to over their lifetime.
They then used that number to calculate the impact lead had on mental health, intelligence and personality.
In general, the higher the levels of lead exposure, the greater the toll on their mental health.
Using these estimates, they calculate that there were 151 million additional mental illnesses created by lead exposure since 1940.
Between 1976 and 1980, for example, they estimated that more than 19 million Americans had blood lead levels above the CDC’s recommended threshold of 3.5 micrograms of lead per 0.1 liter of blood. That represented about 99 percent of the population at the time.
Their estimates show a steady decline in the number of people with high blood lead levels, reaching an all-time low between 2011 and 2015 of 1.4 percent of the population, representing about 280,000 people.
They predicted that blood lead contamination was more common in people born between 1965 and 1980, because leaded gasoline use peaked in the 1960s and 1970s.
Children are more vulnerable to lead exposure because their brains are still developing. Damage caused to the nervous system during crucial years of development may never be repaired, but at any age, lead toxicity can damage the brain, researchers say.
The study authors said, “Childhood lead exposure has likely been a significant and underappreciated contributor to psychiatric illness in the US over the past century.”
The map above from the lobbying group Natural Resources Defense Council (NRDC) shows populations served by drinking water with the highest levels of lead in their home water, usually due to old pipes. Florida had highest concentration of lead pipes, independent study showed
However, they point out, it’s not that all people who were exposed to high levels of lead immediately developed mental health problems.
Instead, prolonged exposure to the heavy metal likely led to frequent, low-level damage to the nervous system.
This sustained damage could then open a person to the development of psychological conditions, making normal and worrying life events more difficult to cope with, for example.
Dr. Reuben compared this to a person who has a mild physical illness, such as a mild fever. He said: “You wouldn’t go to the hospital or seek treatment, but you would struggle a little more than if you didn’t have a fever.”
This is not the first study to link lead with mental effects.
A 2022 study from the same Duke and FSU research group found that exposure to leaded car exhaust may have “stolen” a 824 million collective IQ points of 170 million Americans since 1940.
In a 2019 studyResearchers from the US, UK and New Zealand who followed 579 New Zealand children for 30 years determined that high levels of childhood blood lead lead to long-term changes in personality and mental health.
Children with high lead levels became less conscientious, agreeable adults, and more likely to suffer from depression, ADHD, or anxiety.
Other studies have linked lead to a number of other health problems. This includes hearing problems, infertility, high blood pressure and kidney dysfunction.
The combined weight of evidence on the harms of lead has led to massive government intervention. More recently, the EPA announced it would release billions in funding to help replace lead pipes in small water systems.
They ordered the pipes replaced by the end of the decade.