No, they didn’t poison us. They actually tried to prevent companies from poisoning us. But they did this by poisoning people. Confusing, yes, but fascinating.
Sources:
https://www.esquire.com/food-drink/food/a23169/poison-squad/
The Poison Squad: One Chemist's Single-Minded Crusade for Food Safety at the Turn of the Twentieth Century, by Deborah Blum
https://www.nytimes.com/2018/10/16/books/review/poison-squad-deborah-blum.html
https://gastropod.com/keeping-it-fresh-preservatives-and-the-poison-squad/