Estimated maximum thyroid doses from 129I releases from the Hanford Site for the years 1944-1995

129I, a very long lived fission product, persisted in the environment after discharge from the chemical reprocessing plants at Hanford. The significance to human health is evaluated by considering the maximum possible impact it might have. Allowing the total production of 129I to be discharged to the air and considering the location where the maximally exposed individuals reside, the lifetime cumulative thyroid dose is calculated as a function of birth vear. The maximally exposed individual at the maximum exposure location was born in 1954 and accumulates a thyroid dose between 1954 and 1995 of slightly over 9,000 μSv (900 mrem) at an average rate of 220 μSv (22 mrem) y-1. Over the same period of time, the soft tissue dose from background radiation due to both external and internal radiation is about 38,000 μSV (3,800 mRem)