Until 1937, there was no federal regulation for new drugs being introduced into the United States. An unscrupulous person could mix a bunch of chemicals in his bathtub, slap them in a bottle, and sell this to anyone foolish enough to buy it. This came to a halt with the creation of Elixir Sulfanilamide, an antimicrobial drug that was concocted by the S. E. Massengill Company. There was a huge Sulfa craze going on at the time and they wanted to cash in on the sensation, so they mixed their own special version which added raspberry flavoring and used diethylene glycol as a solvent.
Now, it turns out that diethylene glycol is incredibly poisonous to humans. If you ingest just a tiny bit, there’s a good chance you’ll be pushing daisies before the end of the day. The S. E. Massengill Company didn’t know this when they made the drug, though, because that would have required testing, and research, and a person actually dipping their finger in to taste the powder. The manufacturer thus started marketing their fine new medicinal product to the masses, neglecting to add the skull and crossbones on the outside label that is customary in these cases.
Within a month, a hundred people had died. The Food and Drug Administration was called in to investigate, and they quickly discover the fatal culprit (it didn’t hurt that many of the victims still had bottles of Elixir Sulfanilamide clutched in their necrosis-ridden fingers.) There was a huge public outcry, the chief chemist of the manufacturer committed suicide, and this incident led to the direct passing of the 1938 Food, Drug, and Cosmetic Act, which requires that safety tests be performed on new medicines before they are released on the market. So that’s why you (probably) don’t have four arms and two heads.