Leaded gasoline has been a former experiment in population-wide reduction of intelligence and increase of aggressiveness. Supposedly that affected that 80's, but I am not aware of systematic studies on that.
https://theconversation.com/a-century-of-tragedy-how-the-car...
(smog used to be terrible - I lived through the latter half of that period, am I can't even relate to how awful it used to be... friends and I remember walking in midtown Manhattan, blowing our noses and it being black... I can't even imagine pre-1980 let alone pre-1970... https://timeline.com/la-smog-pollution-4ca4bc0cc95d )
... In automobiles.
Lead is very much in use for aircraft fuel, just google AVGAS.