A new study by researchers at Duke University and Florida State University has found that exposure to car exhaust containing leaded gas during childhood stole IQ scores from more than 170 million Americans alive today, according to Medical Xpress.
The study findings, published in the journal Proceedings of the National Academy of Sciences, suggest that Americans born before 1996 may now be at greater risk for health problems associated with lead exposure, such as faster aging of the brain.
In 1996, the United States banned leaded gas for cars, but the researchers said anyone born before that year had concerning high lead exposures as children.
Lead toxicity is associated with serious consequences for the health of children. Constant lead exposure attacks the brain and central nervous system, causing convulsions, coma, and even death.
Experts say there is no safe level of exposure at any point in life. Children are especially vulnerable to lead toxicity, which can impair their brain development and lower their cognitive function.
Author Aaron Reuben said, “Lead is able to reach the bloodstream once it’s inhaled as dust, or ingested, or consumed in water. In the bloodstream, it’s able to pass into the brain through the blood-brain barrier, which is quite good at keeping a lot of toxicants and pathogens out of the brain, but not all of them.”
One of the major ways lead invaded the bloodstream was through the automotive exhaust.
The researchers used publicly available data on U.S. childhood blood-lead levels, leaded-gas use, and population statistics. They determined the burden of lead exposure by every American who is alive in 2015. They then estimated lead’s effect on our intelligence by calculating IQ scores.
They said there were stunned by the findings. Co-author Michael McFarland said, “I frankly was shocked. And when I look at the numbers, I’m still shocked even though I’m prepared for it.”
As of 2015, over 170 million Americans (nearly 50% of the U.S. population) had clinically concerning levels of lead in their blood when they were children. They were also found to have lower IQ levels, putting them at greater risk for long-term health issues, such as reduced brain size, mental health illness, and cardiovascular disease in adulthood.
Reuben said, “Millions of us are walking around with a history of lead exposure. It’s not like you got into a car accident and had a rotator cuff tear that heals and then you’re fine. It appears to be an insult carried in the body in different ways that we’re still trying to understand but that can have implications for life.”
