Estimation of the radiation dose of 107Pd in palladium products and preliminary proposal of appropriate clearance level

The effective radiation dose of palladium under the assumption that it is contaminated with 107 Pd (1 Bq/g) is estimated through four exposure pathways: the inhalation of airborne particles emitted from an automobile exhaust control catalyst, ingestion via food or drinking water, ingestion of palladium in saliva after release from a dental application, and inhalation exposure of dust in the work place. The highest dose (3.17 × 10 −9 μSv/y) was estimated in adult workers manufacturing palladium products. Considering variations in parameters and possible exposure pathways, it is concluded that this is the critical group for determining the clearance level of 107 Pd. The clearance level, which is defined as a 107 Pd concentration providing less than 10 μSv/y in any exposure pathway, is calculated as 3.16 × 10 3 Bq/g.