Lead exposure has lowered the IQs of almost half of the U.S.

A new study reveals how the now banned neurotoxin messed with people’s brains.

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In 1923, lead was first added to gasoline to help keep car engines healthy, but unfortunately, our reliance on automotive transportation came at the cost of our own health. According to a substantial new study, lead from gasoline is responsible for reducing the IQ of about half of the U.S. population.

The journal Proceedings of the National Academy of Sciences published a peer-reviewed study on the effects of gasoline containing lead on Monday, focusing on people born before 1996, the year America banned gas containing lead, replacing it with safer alternatives. Researchers from Florida State University and Duke University found that childhood lead exposure cost participants an average of 2.6 IQ points each, which translates to an estimated 824 million points lost from 170 million Americans alive today. In most cases, losing 2 to 3 points off of your IQ won’t alter your life but for those with developmental issues, those points could mean the difference between being able to live on your own or not.

"Lead is able to reach the bloodstream once it's inhaled as dust, or ingested, or consumed in water," co-author of the study Aaron Reuben, told Science Daily. "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."

Lead is a neurotoxin, considered unsafe to our bodies at any level of consumption and is linked to a litany of health issues. A small sampling includes a heightened risk of developing ADHD, developmental problems, hypertension, renal failure, reproductive developmental problems, and more — and that’s just in children. There’s a whole separate list for adults.

Exposure to lead in gasoline is primarily due to car exhaust inhalation. Over the years, gasoline consumption has fluctuated and so has the amount of lead in it, and this range affected participants differently based on their age and circumstances. The most affected cohort were people born in the 1960s and ‘70s, losing an average 6 to 7 (or more) points. This is because regulations during those decades were the most lenient and gasoline consumption were the highest.

And because America can’t swing a bag without disproportionately hurting people of color, Black families had it significantly worse than white ones. According to the study and many others, Black children were exposed more often to lead and in greater quantities than white children, and co-author Michael J. MacFarland intends on researching these long-term effects on the Black community. The racial disparity is believed to be linked to infrastructure issues, housing discrimination, and environmental factors that affect drinking water in low income and minority neighborhoods. One example this is the mostly Black population of Flint, Michigan, the site of one of the worst water crises in America.

As a child of the 80s, I remember my childhood was filled with fear of possible asbestos in the attic and lead paint on school walls. Turns out, escaping to the great outdoors, unless it was far, far away from a parking lot, wasn’t actually so great for a big portion of the country, either.