Between 1949 and 1951 about 100 PBq of intermediate and low level liquid radioactive wastes were released into the Techa River (Southern Urals, Russia). To estimate the radiation exposure of Techa River residents having taken place in the past, EPR measurements of tooth enamel were performed. The cumulative dose obtained by EPR, however, is due to both, external photons and internal 90Sr incorporated in enamel and dentin. To provide estimates of the 90Sr content in the teeth tissue, three supplementary methods are used: visualization and mapping of the 90Sr distribution in tooth tissue using Imaging Plates. measurements of the90Sr activity in tooth tissue samples using a β-spectrometer.. measurements of dose rate due to 90Sr in tooth samples using thin-layer Al2O3:C TL dosimeters.