Earlier today, I noticed a YouTube video about a deadly book. It turned out that it wasn't that its contents drove people insane, but rather, the wallpaper specimens in it caused arsenic poisoning.
I did some searching by Google. I wondered if anyone had ever written a historical survey of how humanity had unintentionally poisoned itself through the ages - from Roman plumbing to tetraethyl lead in gasoline, and including Victorian green wallpaper - and haven't found one yet.
But I did learn that William Morris, famed for his Golden type, thought the doctors opposed to the use of arsenical pigments in wallpaper had gone daft - he wrote, in a letter to a friend, that they had been "bitten by the witch fever"!