In the nineteen twenties automotive engineers made one of the greatest mistakes of the twentieth century. Researchers at General Motors discovered that adding lead to gasoline improved the performance and gas mileage of car engines. Lead was a known poison, but scientists working for automakers and oil and chemical companies said that exposure levels from leaded gasoline would be too low to harm anyone.
By the nineteen sixties a growing body of research proved them wrong. Even low levels of lead exposure were harmful. Lead is toxic to nerve cells in the brain, and the developing brains of children are especially susceptible. Use of leaded gasoline peaked between the late nineteen sixties and the early nineteen eighties. By 1996 leaded fuel for cars was banned in the United States. By 2021 lead use in gasoline was banned worldwide. The disastrous consequences of this mass lead exposure are still being discovered.
In 2023 a team of American researchers published a study showing that about half of all Americans alive today were exposed to dangerous levels of lead when they were children. This amounts to one hundred and seventy million people. They are all at greater risk of developing neurodegenerative diseases such as Alzheimer’s disease when they get old, as well as mental illness, and heart attacks. Further, the researchers estimate the exposed people suffered a loss of intelligence amounting to an average of 2.8 points on a standard intelligence test. Those with the heaviest exposure died. Hundreds of children died every summer during the nineteen sixties from severe lead poisoning. The cost of this environmental mistake has been high.