Representative doses to members of the public from atmospheric releases of (131)I at the Mayak Production Association facilities from 1948 through 1972.

ABSTRACT

Scoping epidemiology studies performed by researchers from the Southern Urals Biophysics Institute revealed an excess prevalence of thyroid nodules and an increased incidence of thyroid cancer among residents of Ozersk, Russia, who were born in the early 1950s. Ozersk is located about 5 km from the facilities where the Mayak Production Association produced nuclear materials for the Russian weapons program. Reactor operations began in June 1948 and chemical separation of plutonium from irradiated fuel began in February 1949. The U.S.-Russia Joint Coordinating Committee on Radiation Effects Research conducted a series of projects over a 10-year period to assess the radiation risks in the Southern Urals. This paper uses data collected under Committee projects to present examples of reconstructed time-dependent thyroid doses to reference individuals living in Ozersk from (131)I released to the atmosphere for all relevant exposure pathways. Between 3.22 × 10(16) and 4.31 × 10(16) Bq of (131)I may have been released during the 1948-1972 time period, and a best estimate is 3.76 × 10(16) Bq. In general, younger children incur greater thyroid doses from (131)I than adults. A child born in 1947 is estimated to have received a cumulative thyroid dose of 2.3 Gy for 1948-1972, with a 95% confidence interval of 0.51-7.3 Gy. Annual doses were the highest in 1949 and a child who was 5 years old in 1949 is estimated to have a received an annual thyroid dose of 0.93 Gy with a 95% confidence interval of 0.19-3.5 Gy.