Dietary intake evaluation and dosimetric modelling for the Techa River residents based on in vivo measurements of strontium-90 in teeth and skeleton

Explanations are given for the models and algorithms that are utilised to reconstruct the doses due to the incorporation of 90Sr in the inhabitants of the Techa riverside villages. A model for the 90Sr accumulation and excretion in the tooth enamel is employed to derive the relative intakes of 90Sr in the years 1950-1959. The measurements of beta-ray activity on the surface of the front teeth of persons born between 1940-1959 are used to derive the relative intakes in different calendar years and the transfer functions to the tooth enamel as a function of age. This derivation is based on a non-linear optimisation algorithm, to fit the observed average count rates for different birth cohorts in a village. The data for the village of Muslyumovo are used as the reference data set. Absolute values of the strontium intake are derived from the relative values by a fit to the measurements of the 90Sr body burdens that were performed after 1974. A model has been developed for the age-dependent metabolism of strontium in the skeleton. The computations in terms of this model are in reliable agreement with experimental data on strontium in man.