Feasibility of an epidemiologic study of thyroid neoplasia in persons exposed to radionuclides from the Hanford nuclear facility between 1944 and 1956.

Between 1944 and 1956, approximately 19.6 PBq (530,000 Ci) of 131I were released to the atmosphere during Pu reprocessing for nuclear weapons at the Hanford nuclear facility in southeastern Washington state. For these years, we summarized historical records of quarterly 131I atmospheric releases and vegetation concentrations measured in nearby communities. We used these data and other reported environmental measurements to make preliminary estimates of maximum doses to the thyroid for the general public. We also computed the statistical power for an epidemiologic study of thyroid neoplasia in birth cohorts of children born in two counties near Hanford during the years of highest exposure. These estimates suggest that an epidemiologic study would be feasible if the actual average radiation doses in the exposed population were no less than one-tenth the preliminary maximum doses. Our analyses also suggest that it may be more appropriate to stratify the exposed population by cumulative dose in order to examine the relation between radiation exposure and thyroid neoplasia.