Correction factors in the EPR dose reconstruction for residents of the Middle and Lower Techa riverside

During 1949-1956, the first Soviet nuclear weapons plant, Mayak, released a bout 7.6 x 10(7) m(-3) of liquid radioactive waste with a total activity of 10(17) Bq into the Techa River (Southern Urals, Russia). Sr-90 contributed 11.6% to the total waste radioactivity. As a result of these radioactive d ischarges, about 28,000 local residents were exposed to ionizing radiation, and some of them received relatively high doses. Internal exposure of the population residing at the Middle and Lower Techa riverside was mostly from Sr-90 deposited in bone and tooth tissues. In order to reconstruct radiati on doses to this population group, a study of 35 teeth extracted from local residents was carried out using electron paramagnetic resonance measuremen ts. A total of 73 samples from these 35 teeth (tooth enamel, 33; crown dent in, 20; and root dentin, 20) were prepared and measured with electron param agnetic resonance. The study revealed high doses (up to 15 Gy) absorbed in tooth enamel of the individuals born during 1945-1949, which was attributed to very high local Sr-90 concentration in tooth enamel of this particular age group in the population. The analysis presented here takes into account (a) the time courses both of the release/intake of Sr-90 and of the tooth formation, and (b) expected variations in measured absorbed doses due to di ffering geometric sizes of tooth structures. This methodology enables a mor e consistent picture to be developed of the Sr-90 intake by the Middle and Lower Techa riverside population, based on electron paramagnetic resonance tooth dosimetry.