Estimation of whole-body content of 137Cs from a single urine sample. Experience from areas in Russia contaminated after the Chernobyl accident

Between 1991 and 1997 measurements of the body burden of 137Cs were performed in people living in the Bryansk region of Russia. A single urine sample was also collected for many of the measured persons. The possibility of estimating the whole-body 137Cs from a single urine sample was investigated by comparing the body burden of 137Cs derived from field measurements with data on the urinary excretion of 137Cs, using various normalisation parameters. Coefficients for assessing the body burden from a single urine sample were calculated for each method. The in vivo measurements were carried out using a 63 mm diam. x 63 mm NaI(Tl) detector and a single-channel analyser in villages in the Bryansk region of Russia, in September each year. The urine samples were collected from adults as well as from children, and later analysed for 137Cs, potassium and creatinine concentrations. The correlation between whole-body content and urinary excretion of 137Cs did not improve by introducing potassium or creatinine normalisation. This study indicates that the most reliable method to estimate 137Cs body burden from urine analysis is simply to use the concentration of 137Cs. Age and sex dependent factors for the calculation of 137Cs body burden from a single urine sample are presented. (author)