Strontium metabolism in teeth and enamel dose assessment: analysis of the Techa river data

People living on the banks of the Techa river were exposed to Sr-90 in the early 1950s. Data obtained by radiochemical measurements of extracted perma nent teeth, Sr-90 autopsy measurements in bone and tooth samples, in vivo m easurements of surface beta activity df the anterior teeth and whole-body c ounter (WBC) measurements of Sr-90 in the skeleton have been analyzed. Surf ace beta activity measurements indicate a biological half-life of Sr-90 of about 35 years in enamel. The WBC measurements have been performed since 19 74 and a model for the age-dependent strontium retention in human bone has been used to extrapolate to previous time periods when the other measuremen t results were obtained. For the first decade after the intake, the ratio o f the Sr-90 concentrations in teeth and bones were found to decrease with a ge at the time of major intake, from about 10 for 1-year-old children to ab out 0.3 for adults. There was a considerable variability of individual data within each age group. For adults, the correlation between Sr-90 in skelet on and teeth was not high at 0.47 according to radiochemical data for poste rior teeth (molars and premolars) and 0.43 according to measurements of sur face beta activity for anterior teeth. For children and adolescents there w as no correlation between individual measurements in the skeleton and teeth . The absorbed dose in enamel due to Sr-90 in dentine has been calculated b y Monte Carlo simulations of the electron transport. The results are in agr eement with EPR measurements of the absorbed dose in the enamel of persons exposed, mainly due to Sr-90 ingestion.