Host: The Japan Radiation Research Society
The purpose of our research is to find ways of radiation protection for a nuclear terror. In this case study, using the dose level map for 1kt nuclear explosion in Tokyo1, we applied the lifetime table method2,3 to estimate the excess cancer mortality rate for the survivors. Data for the estimation were compiled by measuring the population and cancer mortality (according to National Vital Statistics in 2000) and the approximate daytime population density.
The numbers of population affected by radioactive fallout with a wind velocity at 24 km/h in the elliptical spread area were estimated to be 50,000 in level-A (over 4Sv) , 110,000 in level-B (1-3Sv) and 690,000 in level-C (0.1-0.9Sv). The survival probability in a region of level A is presumed to be negligible. The excess risks of cancer mortality were estimated to be 3.4% for men and 2.5% for women in a region of level B, and 0.8% for men and 0.6% for women in a region of level C, respectively.
The shortened lifespan of survivors were estimated to be 0.36 years for men and 0.29 years for women in a region of level-B, and 0.09 years for men and 0.07 years for women in a region of level-C, respectively. These figures for shortened lifespan are remarkably low for the survivors with high doses. The estimated figures from this study coincide with the lifespan for the survivors near the ground zero after the nuclear bombing in Hiroshima, 1945.
References
[1] Takada J., Nuclear weapon terrorism in Tokyo, Kodansha (2004) (in Japanese).
[2] Wum LM., et al., Estimating lifetime and age-conditional probabilities of developing cancer, Lifetime Data Anal. 4 (1998) 169-186.
[3] Kamo.K. et al., Lifetime probability of developing cancer in Japan, Kouseino-Sihyou 52 (2005) 21-26 (in Japanese).