Potable alcohol was so hard to come by during Prohibition that people often resorted to drinking industrial alcohol like the kinds used to disinfect wounds. The only way to get your hands on it, however, was to steal it. Eventually, the US government got so fed up with the level of alcohol theft that it began poisoning its own supply to render it fatal if consumed.
"By mid-1927," Deborah Blum writes for Slate, "the new denaturing formulas included some notable poisons — kerosene and brucine (a plant alkaloid closely related to strychnine), gasoline, benzene, cadmium, iodine, zinc, mercury salts, nicotine, ether, formaldehyde, chloroform, camphor, carbolic acid, quinine, and acetone."
The result: By 1933, the poisoned alcohol had killed nearly 10,000 people in what came to be known as "chemist's war of Prohibition."