In the beginning of the 1900's, scientists discovered radioactivity. With this discovery, it was found that many natural hot water spas were radioactive. Some people made the correlation of health spa to radioactivity and boom; you had the birth of a medical pseudoscience. So, why did so many people buy into something that we now know to be so harmful?
In the 1920's and 30's, ads for radioactive water, as well as other radioactive products, were very similar. The Radium Spa was an at-home radioactive water cooler. One of their advertising slogans was