Statistical Analysis of Dose Assignments Resulting from Plutonium Bioassays for the Mayak Cohort

M.P. Krahenbuhl1; J.D. Bess1; J.L. Wilde1; V.V. Vostrotin2; K.G. Suslova2; and V.F. Khokhryakov2 (1University of Utah; 2Southern Urals Biophysics Institute)

The conversion of a plutonium bioassay measurement to a dose is a set of predetermined steps based on the model used (Doses 1999). The significance of the dose resulting from incorporated plutonium can only be recognized if the impact of each step is quantified. A method has been developed for the statistical analysis of the bioassay method used on the Mayak cohorts. The method includes classical statistics, Monte Carlo, perturbation, and reliability groupings. The finalized categories are designated with Roman numerals I through V, with "I" being the most reliable. Excluding Category V (neither bioassay nor autopsy), the highest uncertainty in lung doses is for individuals from Category IV—which ranged from 90%–375% for total body burdens greater than 10 Bq, along with work histories that indicated exposure to more than one transportability class. The smallest estimated uncertainties for lung doses were determined by autopsy. Category I has a 32%–38% uncertainty in the lung dose for total body burdens greater than 1 Bq. These results provide: further definition and characterization of the cohort, uncertainty estimates for these plutonium exposure categories and identified parameters that were ill defined and need further characterization to improve the dose assignments.

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