TIL, from a book I'm reading about poisons, why gasoline must be specifically labeled as "unleaded".

Particularly impressed by the description of the man who "died screaming in a straightjacket" after working in a factory that made tetraethyl lead (TEL), that used to be in gas A chemical engineer discovered ~1920 that adding TEL to gas smoothed out the "knocking" in engines. Problem was, TEL was known to be readily absorbed & highly poisonous. That was conveniently overlooked, and oil & gas companies started making it, slowly poisoning their workers.