Heavy metals in artists’ oil paints.

You can always dig into true crime, see what methods are used to kill husbands.

Check out ChubbyEmu on YouTube. He’s a pharmacist who presents strange and interesting medical stories (with dramatic re-enactments) involving unusual chemical exposures that damage and sometimes kill people. Examples: soda, coconut water from a bad coconut, a fermented soup, ivermectin ordered online, lab chemicals stolen by a student and given to a disliked roommate, and so on. Maybe something there will inspire you. ChubbyEmu does a good job of breaking down complex medical into an easily digestible format.