Leaded petrol had a catastrophic mental health impact on 20th century kids
"Many more people experienced psychiatric problems than would have if we had never added lead to gasoline.”
Leaded gas made generations of people living in the 20th century "more depressed, anxious, inattentive or hyperactive".
A new study has confirmed that exposure to car exhaust from leaded petrol had a disastrous effect on vast numbers of people, who suffered personality changes that "made them less successful and resilient in life".
Lead was first added to petrol in 1923 to keep car engines healthy. Unfortunately, this decision was disastrous for people living across the world.
Previous research showed that people born in the 1960s and the 1970s suffered a loss of 6 IQ points on average.
Now Aaron Reuben, a postdoctoral scholar in neuropsychology at Duke University, and colleagues at Florida State University have found that exposure to car exhaust from leaded gas during childhood "altered the balance of mental health in the US population".
What does leaded gas do to the human body?
The researchers estimated that 151 million psychiatric disorder cases over the past 75 years were caused by American children’s exposure to lead. If the results are extrapolated to the rest of the world, well over one billion people could have been impacted (the US makes up about 4% of the planet's population right now).
Americans born before 1996 experienced "significantly higher rates of mental health problems as a result of lead" - meaning that everyone else living in countries using petrol cars probably suffered the same grim fate.
“Humans are not adapted to be exposed to lead at the levels we have been exposed to over the past century,” Reuben said. “We have very few effective measures for dealing with lead once it is in the body, and many of us have been exposed to levels 1,000 to 10,000 times more than what is natural.”
Lead is highly neurotoxic, eroding brain cells and altering brain function after entering the body. There is no safe level of exposure and young children are especially vulnerable to its ability to impair brain development.
Over the past century, lead was used in paint, pipes and solder as well as automotive fuel.
The appalling IQ impact of lead
The new study is one of many that have linked lead exposure to neurodevelopmental and mental health problems, particularly conduct disorder, attention-deficit disorder and depression.
Reuben and his co-authors, Michael McFarland and Mathew Hauer, both professors of sociology at Florida State University, used historical data on US childhood blood-lead levels, leaded-gas use, and population statistics to determine how much lead people living in 2015 had been exposed to.
“This is the exact approach we have taken in the past to estimate lead’s harms for population cognitive ability and IQ,” McFarland said, noting that the research team previously found that lead stole 824 million IQ points from the US population over the past century.
“We saw very significant shifts in mental health across generations of Americans,” Hauer said. “Meaning many more people experienced psychiatric problems than would have if we had never added lead to gasoline.”
“For most people, the impact of lead would have been like a low-grade fever,” Reuben said. “You wouldn’t go to the hospital or seek treatment, but you would struggle just a bit more than if you didn’t have the fever.”
Lead exposure caused significant mental disorders like depression and anxiety, but also greater rates of conditions such as mild distress that impairs quality of life.
Lead’s effect on brain health has also been linked to changes in personality. “We estimate a shift in neuroticism and conscientiousness at the population level,” McFarland said
Leaded gasoline consumption rose rapidly in the early 1960s and peaked in the 1970s. Reuben and his colleagues found that essentially everyone born during those two decades was almost certain sure to have been exposed to "pernicious levels of lead from car exhaust".
The generation that suffered the greatest exposure was Generation X (1965-1980) -the cohort of Kurt Cobain that was characterised by high-profile suicides and books like Prozac Nation.
“We are coming to understand that lead exposures from the past – even decades in the past – can influence our health today,” Reuben said. “Our job moving forward will be to better understand the role lead has played in the health of our country, and to make sure we protect today’s children from new lead exposures wherever they occur.”
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