EPR and TL-based beta dosimetry measurements in various tooth components contaminated by 90Sr

Abstract

Thermoluminescence-based beta dosimetry, previously proposed for the estimate of the internal contamination in teeth, and EPR has been used in this paper to investigate the homogeneity of 90Sr contamination and of dose within nine teeth of one person born in the year of the onset of waterborne radioactive releases of the Mayak plutonium facility. A large deviation of dose and activity distributions in both enamel and radical dentine of the various teeth was observed. Average dose was 27 ± 7 Gy in enamel and 0.90 ± 0.31 Gy in radical dentine. Average 90Sr concentration was 52 ± 8 Bq / g in enamel and 5 ± 2 Bq / g in radical dentine. The observed deviation around the mean value of dose and 90Sr concentration can be explained due to the specific mineral evolution of each tooth at the time of Sr intake. In the same donor, a negative correlation was also observed between radical dentine and enamel for the 90Sr specific activity as well for the dose. Similar analyses performed on one massive molar belonging to a second donor revealed absence of correlation between dose and 90Sr concentration in the same tissue, indicating a dose contribution from 90Sr present in neighbouring tissue compartments. Systematic differences in cumulated dose and activity levels between the lingual and the buccal parts of crown dentine and of enamel were also observed.