Tritium concentrations inside the homes of occupationally exposed workers: Dosimetric implications

For members of the general public living near a heavy water research reactor, about half of the total tritium dose is due to inhalation and skin absorption of atmospheric HTO. However, chronically exposed workers from the reactor facility could carry HTO in their body fluids and may increase HTO concentrations in air inside their homes. We tested the importance of this HTO transfer pathway and have demonstrated that this pathway is not important to members of the general public. The average HTO concentration in the indoor air of an occupationally exposed atomic radiation worker`s residence was higher (55 Bq m{sup -3}) than the indoor air of normal residences (0.4-0.8 Bq m{sup -3}). The higher concentrations were assumed to be from the exhaled HTO vapor of the exposed worker who had an average concentration of HTO-in-urine of 30 kBq L{sup -1} from chronic intakes of low levels of HTO. Urine samples from family members of the exposed worker were also collected and had HTO concentrations between 0.17 and 0.34 kBq L{sup -1}. These concentrations were higher than for individuals (0.006-0.032 kBq L{sup -1}) living in other residences having equal outdoor and indoor concentrations of HTO-in-air. The range of measured HTO-in-urine concentrationsmore » for family members of the exposed worker was in agreement with the prediction of a metabolic model for the estimated daily intakes of tritium (1.3 kBq). The HTO vapor in the indoor air of the exposed worker`s residence contributed about 98% of the daily tritium intakes. The annual average tritium dose to family members (9 {mu}Sv) were well below the recommended public annual dose limit (1 mSv). We conclude that, for a few members of the public living near the research reactor, daily intakes of tritium may be related to HTO exhaled by the exposed worker, as well as to tritium transported by the atmosphere from the reactor site.« less