Cesium-137 body burden in Japanese from 1967 to 1975

Cesium-137 concentrations in Japanese male adults were measured monthly during 1967 to 1975 by whole body counting. The 137Cs content decreased rapidly until 1968, then the reduction rate was considerably decelerated, being probably affected by the French and Chinese nuclear testing. A small rise was observed at the end of 1970, and its causes have been multilaterally studied from the radioecological viewpoints, which has not resulted in a clearcut conclusion. Daily intake estimated from body burden varies in a wide range but, on the average, agrees well with the reported values based on the radiochemical analyses of foods. The integrated absorbed dose from January 1967 to April 1975 is calculated to be 2.5 mrads. The authors re-emphasize the importance of the periodic measurement of human population. (author)