As with many world-changing discoveries, people initially went a bit overboard with radioactivity. The atomic process that causes radiation was discovered by Henri Becquerel in 1896 and studied further by Marie and Pierre Curie in the following years. And while radiation exposure is now known to be highly lethal, in the early 20th century, products with radioactive properties were believed to be beneficial to one’s health. 

One such item was Doramad, a toothpaste made by the German company Auergesellschaft, which used traces of thorium (a radioactive element) in its teeth-cleaning formula. Advertisements urged customers to “protect yourself by using the biologically active, radioactive, Doramad toothpaste.” (If this ad didn’t make you want to brush your teeth, what would?) 

Doramad’s packaging included the description, “Special biological healing effects by radium rays. A thousand times medically prescribed and recommended.” And the back of the tube claimed the following: “What does Doramad do? Through its radioactivity, it increases the defenses of teeth and gums. The cells are charged with a new vigorous life energy, which inhibits bacteria in their destructive ability. Hence the exquisite prevention and healing effect on gum diseases.” 

Radioactive elements were thought to have beneficial health properties at the time, including for teeth; we now know that the opposite is true, of course. Doramad was sold from the 1920s until the end of World War II, by which point the dangers of radiation were better understood — including by scientists on both sides of the conflict attempting to develop a nuclear bomb.