Many people have heard of the unfortunate women who in the 1920s got cancer because they painted dials of wrist watches with radioactive radium-226. Radioactive elements in sealed tubes are marketed in timepieces, ordinary compasses, marine compasses, marine navigation instruments, markers, signs, indicators, exit signs, step markers, mooring lights and buoys, public telephone dials, light switch markers, bell pushes and miniature light sources. The radionuclides involved are tritium and krypton-85. Dental porcelains are marketed containing a combination of radioactive uranium and cerium, aimed at simulating the fluorescence of natural teeth in daylight and artificial light. The mantels of Coleman lanterns are made of radioactive thorium.
Manufacturers are reluctant to discuss radioactivity in their products.
We must stress that the levels of radioactivity in these products are low. Still, as new evidence becomes available, radioactivity seems to be more dangerous to humans that previously realized. Since that time, studies have been underway to estimate the radiation doses received by various individuals and the resulting medical effects. In 1965, calculations of the radiation dose were used throughout the world to set permissible radiation exposure levels. The risk is greater among adults but greater still among children.