Tritium intake by exposure to plastic case watches.

In recent years tritium has been used in plastic case watches as permanent light sources on watch dials. To measure the release of tritium through the plastic cases, 82 different waterproofed watches were immersed in a water bath for 24 h, and the tritium concentration of the water was measured. The mean tritium release rate was 24,400 Bq d(-1) ranging from 110-162,000 Bq d(-1).