The Lead Cohort Series

The leaded-gasoline era ran for fifty years and it was the largest uncontrolled cognitive experiment in American history. Nobody signed a consent form and nobody got follow-up care. The children who lived through the worst of it are the grandparents now, and most of them have never seen their own data.

This series puts that data in front of them, one chart and one study at a time. It starts with the basic link between tetraethyl lead in the gas tank and lead in the blood of every child in the country. The rest of the series builds on that.

1, Foundation Chart
Foundation Chart

When you put it in the gas tank, it ended up in the kids.

Tetraethyl lead added to gasoline (1925-1996, EPA + ATSDR) and the geometric mean blood lead in US children ages 1-5. Gasoline lead left tailpipes as airborne particles and got into children through air, dust, and soil. The two curves line up because they are tracking the same chemical.

5x
the average US kid in 1970 had ~5x the blood lead level CDC now flags as toxic (3.5 µg/dL reference value, adopted 2021)
10x
urban and Black kids in NHANES II (1976-80) averaged 6-10x the current CDC reference
1972
peak TEL: ~252,000 short tons of tetraethyl lead added to US gasoline in a single year
Note on subpopulation: the orange line shows the US average child BLL. NHANES II 1976-80 found urban Black children averaged 22 µg/dL; inner-city children 1-5 averaged ~30 µg/dL. The damage was distributed unevenly even within the peak cohort.

Sources: EPA National Lead Emissions · ATSDR Pb Toxicological Profile · NHANES II/III/Continuous geometric means (CDC) · Annest et al. 1983 (NHANES II reanalysis); Mahaffey et al. 1982 (NEJM); pre-1976 child BLL estimated from city cohort studies (Boston 1970-72, Pittsburgh 1973). CDC Blood Lead Reference Value 3.5 µg/dL (October 2021).
2, IQ Test with Lead Mode
Cognitive Demonstration
3, Digit Symbol Coding
Digit Symbol Coding
4, Quick Screen Cognitive Assessment
Cognitive Assessment
End of preview.