A new study published in Journal of child psychology and psychiatry has calculated that millions of Americans face mental disorders attributable to childhood exposure to lead – through the exhaust fumes of leaded gasoline cars.
Researchers found that those born between 1966 and 1986Generation X— were most exposed to lead, since they were children during the peak of leaded gasoline use. They also experienced the largest increase in mental illness symptoms, according to the study.
A study by Aaron Reuben, a postdoctoral fellow in neuropsychology at Duke University, and colleagues Michael McFarland and Mathew Hauer of Florida State University found that more than half of the current US population has been exposed to “neurotoxic levels” of lead through its use in gasoline.
Lead was first added to gasoline in 1927 to keep car engines healthy; its use was gradually withdrawn from the market starting in the 1970s due to health and environmental concerns, and was completely phased out in 1996.
To find out what effect exposure to fumes containing lead had mental healthresearchers combined blood lead data from the publicly available National Health and Nutrition Examination Surveys (NHANES) with historical data on leaded gasoline to estimate childhood blood lead levels from 1940 to 2015. They then calculated increases in mental health symptoms in populations known to be associated with lead exposure by calculating “mental illness scores”.
“This is the exact approach we’ve used in the past to estimate lead damage to cognitive ability and population IQ,” McFarland said. Science Daily, noting that the research team had previously determined that lead had reduced the IQ scores of the US population by 824 million over the past century.
Their latest research estimates that 151 million cases of psychiatric disorders—including depression, anxiety, and hyperactivity—over the past 75 years can be linked to childhood lead exposure.
“We’ve seen very significant changes in mental health across generations of Americans,” Hauer said Scientific journal. “Which means many more people have experienced psychiatric problems than would have if we had never added lead to gasoline.”
However, the researchers point out that this study does not prove causation. They also note that it is based only on exposure to leaded gasoline, not taking into account other exposures to lead from lead pipes, contaminated food and soil, or airborne dust from lead-emitting manufacturing, waste incineration and lead processing operations.
How does lead affect the brain?
Lead exposure is most dangerous for children, and it can be especially destructive to brain development early in life, researchers explained in the study. They noted that childhood lead exposure can result in reduced cognitive ability, fine motor skills and the ability to regulate emotions.
Numerous other studies link childhood lead exposure to mental disorders, the researchers wrote, including depression and anxiety, as well as personality changes which lead to neuroticism and weaker impulse control.
Even small amounts of lead can cause serious health problems, according to Mayo Clinic. Children under 6 are particularly vulnerable to the effects of lead exposure, which can cause developmental delays, learning difficulties and irritability, among other symptoms in children and infants, from lethargy and vomiting to hearing loss and seizures.
Babies exposed to lead before birth can be born prematurely, have lower birth weights and slow growth – while adults can experience high blood pressure, joint and muscle pain, memory problems, headaches, mood disorders, reduced sperm count and miscarriage or stillbirth. as a result of lead poisoning.
“Humans are not adapted to be exposed to lead at the levels we’ve been exposed to over the last century,” Reuben said Scientific journal. “We have very few effective measures to deal with lead once it’s in the body, and many of us were exposed to levels that were 1,000 to 10,000 times higher than naturally occurring.”
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