Studies of Radioactivity Produced by the Hiroshima Atomic Bomb: 2. Measurements of Fallout Radioactivity

A Review of Forty-Five Years Study of Hiroshima and Nagasaki Atomic Bomb Survivors I. DOSIMETRY

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Three studies of fallout measurements were reviewed for the discussion of possible radioactivity intake from the Hiroshima atomic bomb. The first study discussed correlations between enriched ²³⁴U and ¹³⁷Cs specific activities from the measurement of soil samples collected in the “black rain” area. The second study measured ¹³⁷Cs activity on the rock and roof tile samples collected in the hypocenter area immediately after the explosion. Some of the rock and roof tile samples collected near the hypocenter had a small but detectable amount of ¹³⁷Cs activity. However, it has been determined that ¹³⁷Cs exposure, for example, was negligible compared with DS86 dose estimates, since these activity levels were low. The third study detected ⁹⁰Sr activity in some of the specimens of human bones exhumed on Ninoshima Island. This study compared the difference in activity between the bone head and shaft, with higher activities obtained in the bone head. This fact suggests a short intake period for this activity, however, the levels of ⁹⁰Sr contamination were too low to allow a discussion of the exposure risks.