A woman temporarily visiting the Brjansk area in southern Russia ingested, without her knowledge, 35.5 kBq of 137Cs in a single mushroom meal. Seven months later the woman became pregnant. Her total body content of 137Cs and 40K was measured regularly in a whole-body counter for three years following this intake. Data were thus available for the whole-body content for the periods before, during, and after pregnancy. Urine samples were collected regularly, and on two occasions breast milk was sampled. The 137Cs concentration in urine and breast milk was analyzed with a gamma-ray spectrometer. The body content of 137Cs decreased with a biological half-time of 107 d [95% confidence interval (CI): 106,109] before pregnancy, 58 d (95% CI: 53,64) during pregnancy, and 96 d (95% CI: 43,346) after the child was born. The ratio between the concentration of 137Cs in the urine (Bq/L urine) and in the body (Bq/kg body weight) increased during pregnancy from 18 ± 6% to 35 ± 6% (± 1 SD). The results show that there was a rapid decrease in the biological half-time of 137Cs at the beginning of the pregnancy and an increase after the child was born. The biological half-time during pregnancy was 54% of the half-time before pregnancy, which was reflected in the increased excretion of 137Cs in the urine. The ratio of the 137Cs concentration in breast milk to the whole body was 15% in the first month of breast-feeding. The effective dose, E, to the mother as a result from this intake was estimated to be 0.5 mSv, and the absorbed dose to the fetus was 0.06 mGy. These results are consistent with those reported elsewhere.
*Department of Radiation Physics, Lund University, Malmö University Hospital, SE-205 02 Malmö, Sweden.
Manuscript received 3 March 1999;
revised manuscript received 12 October 1999, accepted 20 December 1999)
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