Body burdens of 137Cs in a selected group of male adult residents in Chiba, Japan from 1967 to 1976.

Abstract

Body burdens of 137Cs for Japanese males have shown a decreasing tendency from about 3.6 nCi in 1967 to 1.0 nCi in 1976 with the exception of a small rise for the period from 1970 to 1971. The reduction rate of the dose differed considerably before and after 1969, with an estimated half-time of 1.5 yr for the period before 1969 and 7.1 yr after 1969. The accumulated internal radiation dose was 7.6 mrad from 1964 to 1976. About a quarter of the dose, 2.3 mrad, was estimated to result from fairly recent nuclear explosions. The dose commitment by the year 2000 is estimated to be 8.8 mrad, which is smaller than the annual dose due to 40K in an averaged Japanese male, 19.2 mrad.