Recent researches on the effects of radiation

Radiation effects of atomic bomb survivors of Hiroshima and Nagasaki were reviewed. About 80% of the citizens of both cities were investigated. The relations between the radiation dose and immunological functions of the lymphocytes, chromosome aberrations, mutation in plasma and red blood cells, incidence of tumor and pericarditis, and mortality were described. The chromosome aberration was proportional to the radiation dose and the square of the dose in Hiroshima and Nagasaki, respectively. The chromosome aberration rate of the children of the survivors (F1) was 0.62%. No radiation effects on the mortality of F1 were observed. For chronology of radiation related neoplasms, the highest relative risk of leukemia was observed during 1957 - 58. However, for myeloma and cancer of the lung, breast, thyroid, and stomach, the risks began to increase several times higher around 1960. The latent period of radiation induced cancer was also discussed. (Nakanishi, T.)