Leaded Gasoline Caused a Global Drop in Human Intelligence

In the 1920s, Thomas Midgley Jr. discovered that adding tetraethyl lead to gasoline prevented engine knocking and improved performance. To prove it was safe, he washed his hands in leaded gasoline and inhaled it at a press conference. For decades, lead poured from car exhaust pipes into the air, soil, and water. The lead settled in ice cores in Antarctica and was found in the blood of children worldwide. Studies later showed that lead exposure caused measurable drops in IQ scores, behavioral problems, and learning disabilities in entire generations of children. Leaded gasoline has been phased out globally, but the damage to human brain development continues to affect millions.