Reconstruction of individual doses to the Semipalatinsk historical cohort subjects : methods and input parameters

A description of the methods to reconstruct the deterministic estimates of individual whole-body dose from external irradiation and dose to thyroid from internal irradiation to radioiodines (131I and 133I) for the subjects (more than 10,000 people) of the Semipalatinsk historical cohort, formed from the residents of ten settlements (Dolon, Kanonerka, Mostik, Cheremushki, Znamenka, Kainar, Karaul, Sarzhal, Kaskabulak and Kundyzhdy) radioactively contaminated during the atmospheric nuclear weapon testing at the Semipalatinsk Nuclear Test Site (SNTS) has been presented. Four significant nuclear tests (#1 - 29 August 1949, #2 - 24 September 1951, #4 - 12 August 1953, and #28 - 24 August 1956) that provided the major contribution to radiation doses to the cohort subjects were identified. For each above mentioned settlement the estimates of settlement-average absorbed dose to air from fallout arrival time to infinity and of radioiodine concentration in pasture grass at the fallout arrival time were calculated. In order to assess settlement-average absorbed dose to air from fallout arrival time to infinity the following sources of input data (if any) related to radiological conditions are used: (1) historical fallout patterns showing isopleths of dose in air from the fallout time of arrival until infinity, (2) historical survey meter readings (exposure rate measurements), (3) present-day thermoluminescence measurements in bricks, (4) present-day 137Cs inventory, and (5) present-day ESR measurements of tooth enamel. Whole-body dose from external irradiation has been mainly determined by the radionuclides deposited on the ground following the passage of the radioactive cloud through a settlement. Dose to thyroid from internal irradiation to radioiodines has been mainly determined due to consumption of contaminated cow's (horse's) milk (koumiss) from grazing animals put on pasture.
A joint U.S./Russian methodology has been applied to derive doses from external and internal irradiation. In order to derive estimates of individual whole-body dose from external irradiation and dose to thyroid from internal irradiation to radioiodines a restricted set of input personal data on the cohort subjects (date of birth, ethnicity, residence history) available in the registry created by the scientists from Kazakhstan and Japan is used. Because of lack of other personal data a life-style and dietary habits typical for a resident from specific age-group and ethnicity is used in dose reconstruction.