It was pretty obvious from the get-go that leaded gas was an absolutely horrible idea, but this was before the mass-media age, so people didn't know that people who worked at the tetraethyl lead plant were going mad so often that it became known as the "looney gas building".[0]

Doses make the poisons, and apparently the dose for some of these chemicals is much, much higher than tetraethyl lead.

Also, apparently the molecular diagram for TEL sorta looks like a hackenkreuz. How appropriate.

[0]https://www.wired.com/2013/01/looney-gas-and-lead-poisoning-...