Levels of 90Sr and 137Cs in the urine of Finnish people

The aim of this study was to estimate the current concentrations of 90Sr and 137Cs in the urine of Finnish people and to estimate the doses. Two to three daily urine samples were collected from 18 adult Finnish volunteers in connection with studies of 137Cs body burdens in 1999-2001. The 90Sr activities in urine varied between 1.4 and 11 mBq l-1. The 137Cs activity in urine varied between 0.36 and 56 Bq l-1. The daily urinary excretion was found to be 4.8-17 mBq for 90Sr and 0.81-68 Bq for 137Cs. Assuming that the daily 90Sr intake was constant and that 18% of the ingested activity was excreted in urine, the mean intake in the investigated group would vary between 27 and 96 mBq d-1. Based on these estimated intake values, the respective annual effective internal doses from 90Sr and 90Y varied from 0.3 to 1.0 µSv and from 137Cs from 4 to 350 µSv during the sampling period.