Gasoline is not big business? They had a "scientist" on staff, that proclaimed that leaded fuel was harmless. Who cares about paint, when there are millions of cars driving around blowing lead dust into the air? The (real) scientist who saw a connection needed years to prove it. By digging into the ice in the arctis he was able to prove, that the high lead levels where a recent phenomenon. The documentary Cosmos: A Spacetime Odyssey by Neil deGrasse Tyson [0] tells this story much better than i ever could and much more... Highly recommended!

[0] https://www.imdb.com/title/tt2395695/