Back in the early 20th century, American doctors lobbied very hard to ensure that radium-coated water dispensers sold did indeed contain enough radioactive material to provide “health” benefits.
I just got back from vacation in Germany, and while I was doing research for the trip I found a spa near one of the places I was staying that does radon therapy. From what I could gather on the web site, you sit for multiple sessions in a room with walls made of crushed radon-producing rock, reading, chatting with your neighbors, or having a snooze. Also, they ensure the radon levels comply with the German Spas Association's guidelines and you need a doctor's prescription to get treated.
I recall seeing a documentary about early glow in the dark wristwatches with hand painted radium dials. The painters would occasionally lick the brush tips to make a fine point. A large percentage of them died from terrible forms of lip, mouth and throat cancer.
