Lead exposure has already stolen more than 800 million cumulative IQ points of half of Americans

Lead was originally added to gasoline in 1923 to improve in the functioning of car engines. However, the health of our cars came at the expense of our personal well-being.

According to a new study, childhood exposure to car exhaust from leaded gasoline cost more than 170 million Americans, or over half the population of the United States, 824 million IQ points.

US children born before 1996, according to research by Aaron Reuben from Florida State University, may now be at greater risk for lead-related health problems, such as faster aging of the brain, than children born after 1996.

Although leaded gasoline for automobiles was banned in the United States in 1996, the researchers claim that everyone born before the end of that era, particularly those born during the peak of its use in the 1960s and 1970s, experienced alarmingly high lead exposures as kids.

Lead is neurotoxic, and once it enters the body, it can damage brain cells. As a result, health experts warn there is no such thing as a safe level of exposure at any point in life. Lead’s ability to disrupt brain growth and diminish cognitive ability makes young children particularly vulnerable. Unfortunately, our brains, regardless of age, are ill-equipped to hold it away.

“Lead is able to reach the bloodstream once it’s inhaled as dust, or ingested, or consumed in water,” says Reuben. “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.”

The automotive exhaust was one of the most common ways for lead to enter people’s bloodstreams.

They calculated the potential lifelong burden of lead exposure carried by every American alive in 2015 using publicly accessible data on childhood blood-lead levels, leaded-gas usage, and demographic statistics. They calculated IQ points lost from leaded gas exposure as a proxy for its negative influence on public health using this data to evaluate lead’s assault on our intelligence.

The researchers were stunned by the results.

“I frankly was shocked,” adds Michael McFarland, co author. “And when I look at the numbers, I’m still shocked even though I’m prepared for it.”

More than 170 million Americans (more than half of the population) had clinically concerning levels of lead in their blood as children as of 2015, putting them at risk for other long-term health impairments such as reduced brain size, increased mental illness, and increased cardiovascular disease in adulthood.

The use of leaded gasoline skyrocketed in the early 1960s and peaked in the 1970s. As a result, Reuben and his colleagues discovered that virtually everyone born during those two decades was almost certainly exposed to harmful levels of lead from automobile exhaust.

Even more shocking was lead’s impact on intelligence: it’s estimated that childhood lead exposure reduced America’s cumulative IQ score by 824 million points, or about three points per person on average. People born in the mid-to-late 1960s may have lost up to six IQ points at worst, according to the researchers, while youngsters with the highest levels of lead in their blood, eight times the current minimum threshold to cause clinical concern, may have lost more than seven IQ points on average.

Although a few IQ points may seem insignificant, the authors point out that these changes are significant enough to push those with below-average cognitive capacity (IQ score less than 85) into the category of intellectual disability (IQ score below 70).

“Millions of us are walking around with a history of lead exposure,” Reuben adds. “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.”

Source: 10.1073/pnas.2118631119

Image Credit: Getty

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