Age dependencies of 90Sr incorporation in dental tissues:: Comparative analysis and interpretation of different kinds of measurements obtained for residents on the Techa River

Human teeth have been considered as dosimeters for decades. Methods include the in vivo measurement of Sr-90/Y-90 in teeth,with a tooth-beta counter, the radiochemical determination of Sr-90 in whole teeth, and the measurement of dose in teeth by use of electron paramagnetic resonance. Presented in this paper are results of 2,514 tooth-beta counter measurements, 334 radiochemical measurements, and 218 electron paramagnetic resonance measurements for residents living in settlements along the Techa River. All three kinds of measurements indicate a sharp peak that corresponds to the uptake of Sr-90 by tooth tissue. The results can be interpreted in terms of an intake function for Sr-90 only if the period of calcification of each individual tooth is considered-such detail on a tooth-by-tooth basis is presented in this paper. The conclusion is reached that the tooth-beta counter data are the most reliable in terms of reconstruction of Sr-90 intake; this is due in part to the fact that the tooth-beta counter measures four teeth (all at position 1) with essentially the same time periods of mineralization and because there are a large number of tooth-beta counter measurements. The main utility of electron paramagnetic resonance measurements is considered to be the validation of estimates of external dose; but for this purpose teeth with Sr-90 taken up into enamel must be avoided.