Clair Patterson developed a Lead-dating technique which allowed him to calculate the first ever accurate age for the Earth to be 4.55 billion years.
During these studies he became aware of Lead Pollution emanating from Lead anti-knocking additives in gasoline, namely that we had a 1000 times more lead contamination in our bodies than our ancestors.
This lead to lead being banned in gasoline but not before an arduous battle with the Ethyl Corporation where amongst other things they offered a massive amount of money to Patterson’s University to get rid of him.
Bill Bryson in his marvelous book A Short History of Nearly Everything