TRITIUM EXPOSURE ESTIMATES OF DIAL PAINTERS FROM BIOASSAY MEASUREMENTS - CASE-STUDY AND PROPOSAL FOR A SIMPLE METHODOLOGY

In India, radioluminous dial painting industries consume about 60 TBq of tritium based compounds every year. In all, they employ nearly 100 dial painters who are occupationally exposed to tritium. These small s cale industries are subjected to periodic surveillance and surprise ch ecks regarding safe practices adopted in handling small quantities of radioactivity. Only random data on parameters such as air concentratio n or bioassay results will be available for any assessment by the regu latory agency. A mathematical model has been developed (i) to estimate urine concentration when there is a steady intake of tritium over a f ixed period of work every year, and (ii) to correlate air concentratio n in the working environment with urine assay values of dial painters. The model-predicted mean urine concentration values, derived from mea n air concentration measurements, have been found to be in reasonable agreement with the measured mean urine assay values in two different i nstitutions over the period 1992-1995. The estimated CED for a painter is found to be typically 1.2 mu(S)v.y(-1) per g of the paint handled and the annual occupational exposures are less than 1 mSv which is the ICRP recommended limit for the public.