Tens of millions of Americans born before 1996 suffered from psychiatric disorders as a direct result of exposure to toxic lead.
A major study estimated that leaded car exhaust inhaled before that date 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.
US authorities banned the addition of lead to gasoline in 1996, but fifty years earlier Americans had inhaled fumes full of heavy metals.
Using national data on lead levels in children’s blood and population statistics, Duke University researchers estimated the amount of lead to which all Americans were exposed in 2015. They then determined the effect lead exposure would have on mental health.
Lead is known to damage the nervous system and in turn affects psychology. When inhaled, the lead-filled smog enters the bloodstream through the lungs, where the particles are absorbed by the body, causing inflammation that can cause neurons to die.
This can slow 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 1,000 to 10,000 times higher than lead. what is natural’.
In December 2022, reality TV star Christina Hall announced on her Instagram Story that she had lead and mercury poisoning. She said she suspects her work renovating old homes, which sometimes contain lead pipes, fixtures and solder, may have made her sick. She didn’t talk about exhaust fumes
From 1923 to 1996, lead was used in gasoline to keep engines running smoothly. Lead use reached its peak in 1960-1970 and was banned shortly before the turn of the 21st century.
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Mathew Hauer, co-author of the study and a sociologist at Florida State University, said: “Many more people experienced psychiatric problems than would have been the case if we had never added lead to gasoline.”
In 1923, people started adding lead to gasoline to make the gasoline run more smoothly through engines. It was also added to paint, solder and used to manufacture pipes that supplied drinking water.
Since the 1980s, health authorities have moved to phase out heavy metals from the products Americans depend on.
When lead gas is vaporized, the lead is released into the air, where it can be inhaled by people or settle in the ground.
Although there has been particular attention to the effects of lead in drinking water, the authors of the new paper, published in the Journal for child psychology and psychiatrysaid the product that had by far the most far-reaching impact was car exhausts.
The researchers used national data on blood levels in children, lead gas use over time, and general population statistics to estimate average lead levels in people’s blood from 1940 to 2015.
This number gave them an idea of the amount of lead they were exposed to throughout their lives.
They then used that number to calculate the impact lead had on mental health, intelligence and personality.
In general, the higher the lead exposure, the greater the toll it took on their mental health.
Using these estimates, they calculate that 151 million additional mental illnesses have developed from lead exposure since 1940.
For example, from 1976 to 1980, they estimate 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 levels of lead in the blood – reaching a low of 1.4 percent of the population between 2011 and 2015, equating to about 280,000 people.
They predicted that lead contamination in the blood was most common in people born between 1965 and 1980, because leaded gasoline use peaked between the 1960s and 1970s.
Children are more vulnerable to lead exposure because their brain area is still developing. Damage to the nervous system during crucial developmental years may never recover, but researchers say lead poisoning can damage the brain at any age.
The study authors said: ‘Childhood lead exposure is likely a significant, underappreciated contributor to psychiatric illness in the US over the past century.’
The above map from pressure group the Natural Resources Defense Council (NRDC) shows populations served by drinking water with the highest levels of lead in their home water, mostly due to old pipes. Florida had the highest concentration of lead pipes, a separate study found
However, they note that not every person exposed to high levels of lead immediately developed mental health problems.
Instead, long-term exposure to the heavy metal likely caused frequent, low-level damage to the nervous system.
This damage incurred could then predispose a person to developing psychological conditions, making it more difficult, for example, to cope with normal, distressing life events.
Dr. Reuben compared this to someone who has a mild physical illness, such as a low-grade fever. He said, “You wouldn’t go to the hospital or seek treatment, but you would just be a little more bothered than if you didn’t have a fever.”
This is not the first study to link leading and mental effects.
A 2022 study from the same research group at Duke and FSU found that exposure to leaded car exhaust may have a collective 824 million IQ points of 170 million Americans since 1940.
In a 2019 studyResearchers from the US, Britain and New Zealand, who followed 579 New Zealand children for 30 years, found that high blood lead levels in children lead to long-term changes in personality and mental health.
The children with high lead levels grew into adults who were less conscientious and friendly and more likely to have depression, ADHD or anxiety.
Other studies have linked it to a host of other health problems. This includes hearing problems, infertility, high blood pressure and kidney dysfunction.
The combined weight of evidence about lead’s harm has led to massive government intervention. Most recently, the EPA announced it would provide billions in funding to help replace lead pipes in small water systems.
They ordered the pipes to be replaced by the end of the decade.