Radium
A lot has been said over the years about Radium and its ill effects, and how it relates to horology. Watchmakers typically have had to contend with a vast array of toxic materials, Cyanide, Trichlorethylene, Carbon Tetrachloride, Ammoniated cleaning solutions, both water and hydrocarbon based, Rouges and polishing mediums, and of course, Radium.
I recently had the opportunity to use a Geiger counter on a variety of test subjects, and the results have surprised me.