REEVALUATION OF THE BIOLOGICAL HALF-TIME OF CESIUM IN JAPANESE MALE-ADULTS

After the Chernobyl accident, increased Cs-137 body burdens were measu red for 22 Japanese male adults. An average biological half-time of 10 1 days was estimated. In the 1960s, an average Cs biological half-time of 86 days was reported for 23 Japanese male adults under quasi-equil ibrium conditions in regard to Cs-137 from atmospheric nuclear weapon tests. Comparing the present data with the 1960s results, the differen ce in the biological half-time of Cs at a confidence level of 90% was not significant but had an increasing tendency. When the two groups of data were combined, the biological half-time for Cs was 93 +/- 27 day s for the 45 individuals. Thus, the reference biological half-time sho uld be 90 days for Japanese male adults. Four subjects were studied in both the 1960s and the 1980s. A clear relationship was observed betwe en the increase in half-time and increase in age. (C) 1998 Elsevier Sc ience Ltd. All rights reserved.