RADIOLOGICAL SAFETY ASPECTS OF INDIAN WATCHES CONTAINING TRITIUM

In recent years tritium activated radioluminous paint has become the p referred compound in dial painting by wrist watch industries. Tritium activity in metallic wrist watches has been found to be in the range o f 5.5-18.8 MBq. The release rates of tritium from different watches sh owed considerable variation in the range of 0.2-15 kBq.d(-1) under hum id conditions and indicate dependence on the gross activity level pres ent in the watch. The mean tritium life in watches is 5 +/- 2 years ba sed on gross activity estimated and release rate measured. The annual effective dose to the wrist watch wearer works out to be about 2.5 mu Sv from air concentration through inhalation and percutaneous absorpti on through skin and assuming the highest release rate and continuous w atch wearing conditions. In the worst possible imagined situation, the maximum possible annual skin dose equivalent rate is estimated to be in the range of 6.7 mSv-67 mSv over a 10 cm(2) area. Both the dose est imates are far less than the respective limits recommended by ICRP for the public at large.