During the Prohibition, the manufacture, sale, and transportation of alcohol were made illegal to try to curb Americans' excessive alcohol drinking.
As a response to the restrictions put in place, people would create and distribute their own alcohol, which on its own would occasionally cause alcohol poisonings due to metals and other impurities that commonly taint bootlegged liquor. These bootleggers also would steal and redistill large amounts of industrial alcohol—used in paints, solvents, fuels and medical supplies—and then sell it as drinkable liquor.
As an attempt to stop the bootleggers, and scare people out of drinking alcohol, the U.S. Government, led by President Calvin Coolidge, began requiring a "denaturing" process be performed on industrial alcohols manufactured in the United States, in which chemists added chemicals to the alcohol to make it undrinkable. This usually entailed adding in poisonous methyl alcohol or less lethal bitter-tasting compounds that made the alcohol taste unappetizing.
This didn't have the desired effect, however, as the bootleggers decided to also employ chemists to then "re-nature" the alcohol to return it to a drinkable state. At this point, stolen and distilled alcohol became the main source of liquor in the United States, and the United States Department of the Treasury decided it was time to push harder. To try to make the alcohol even more difficult to be rendered drinkable again, the United States Treasury Department demanded more methyl alcohol be added (up to 10% of the total product), and added much more deadly chemicals to the mix:
- Brucine (a plant alkaloid closely related to strychnine)
- Carbolic acid
- Mercury salts
This almost immediately started causing deaths, and this continued for several years. It is estimated that by the time Prohibition ended in 1933, the federal poisoning program killed over 10,000 people. It should be noted that, as with most tragedies, the poor were disproportionately affected by this, as the wealthy could afford the best whiskey available.