Whether it’s lead paint or lead found in pencils or yes, in gasoline, most of us are more than aware that the less of it we have in our lives, the better. It used to be more ubiquitous, before unleaded gasoline and home inspections that automatically tested the property for lead paint.
Now, a recent study is showing that a generation of Americans likely suffered the loss of at least a few IQ points due to repeated exposures during childhood.
Since lead is a neurotoxin, health experts say there is no safe level of exposure. 90% of children born between 1950 and 1981 had blood lead levels higher than 5 micrograms per deciliter – in 2021, the CDC lowered the acceptable threshold to just 3.5 micrograms per deciliter.
Researchers in this study, published in the Proceedings of the National Academy of Sciences, looked at the consumption of leaded gas (a major source of lead exposure until 1996, when it was banned), historical census data, and records of lead levels in blood.
What they found translates to an average of 2.6 point drop in IQ per person, or a collective loss of 824 million IQ points across 170 million Americans.
That’s a lot of smarts, and I’m sure we all have our ideas on where we would have liked to have spent them, as a country, had they not been sucked away by a poisonous toxin.
The majority of the lost points were accumulated in the 1960s and 1970s, when leaded gas was far more prevalent, with some people of that age losing as many as 7 points apiece.
Since young children are especially vulnerable to both developmental and cognitive damages, study co-author and Duke University PhD candidate Aaron Reuben says they still want to study how exposure as a child impacts an aging brain.
“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.”
The paper also asserts that Black adults under the age of 45 experienced “considerably higher” levels of lead in their blood during childhood compared to their white counterparts, and lead author Michael McFarland told NBC News he plans to further analyze the data to extrapolate how racial disparities play a role in childhood lead exposure.
Experts agree that although IQ is an imperfect indicator for both intelligence and cognitive abilities, it’s the best option when trying to pinpoint brain health impacts caused by specific chemical culprits.
Health sciences professor and lead exposure expert Bruce Lanphear says that the fact that humanity continues to repeat the same mistakes when it comes to chemical pollutants is “tragic.”
“First it was lead, then it was air pollution… Now it’s PFAS chemicals and phthalates. And we can’t stop long enough to ask ourselves should we be regulating chemicals differently.”
Maybe now that we’re going to have a couple of generations whose IQ’s haven’t been negatively impacted by lead exposure, we’ll be able to finally tackle this problem head on.
We can dream, at any rate.