Cesium-137 and Potassium Contents in Low-Teens in Areas of Different Fall-out Levels in Japan

Comparative measurements were performed by the whole body counter equipped in the University of Tokyo with regard to the 137Cs body burdens of 88 Japanese male low-teens in Akita and Tokyo. In spite of the heavy fall-out level in Akita, the mean 137Cs body burden was significantly lower than that in Tokyo where the fall-out deposition was about the half. The major cause of the difference in the body burdens was considered to be the difference in the daily milk consumption volumes in both groups which was disclosed from the results of interview with each subject. The 137Cs content showed very low correlation with potassium content in each group. The fact proposed an important question concerning the effectiveness of the concept of "cesium unit" for describing the level of internal contamination in man. In Akita Prefecture which is located on the northern part of the Japan Sea Coast, the fall-out level of 137Cs is the highest in Japan, and it is about twice as high as that in Tokyo. Since 1967, the authors have carried out a series of investigations with our collaborators including the determination of 137Cs and 40K body burdens of about 2,000 normal Japanese in Tokyo area.