MORTALITY AMONG ATOMIC-BOMB SURVIVORS

The Atomic Bomb Casualty Commission and its successor, the Radiation Effects Research Foundation, have conducted a long-term follow-up study of a cohort of 120,000 atomic bomb survivors and non-exposed controls since 1950. The most recent findings regarding cancer mortality during the period 1950-85 in this cohort, based on the DS86 doses are as follows: 1) The dosimetry change does not alter the list of radiation-related cancers. Some city differences in dose-response previously thought to be real are no longer significant with the DS86 doses. Assuming a linear dose-response, and using estimated organ-absorbed doses, the risk coefficients derived from the two dosimetries are very similar. If larger RBE values are assumed, the disparity between the two dosimetries increases because the neutron dose is much greater in the T65 dosimetry. 2) Besides the well-known increase of leukemia, there also have been demonstrated increases in cancers of the lung, breast, esophagus, stomach, colon, ovary, urinary bladder, and of multiple myeloma, but no increase has yet been observed in mortality from cancer of the rectum, gallbladder, pancreas, prostate and uterus, and of malignant lymphoma. In general, radiation-induced solid cancer begins to appear after attaining the age at which the cancer is normally prone to develop (the so-called "cancer age"), and continues to increase proportionately with the increase in mortality in the control group as it ages. Sensitivity to radiation, in terms of cancer induction, is higher generally for persons who were young at the time of the bomb (ATB) than for those who were older ATB. Non-cancer mortality in the period 1950-78, based on the T65 doses, which is the most recent published report, did not show an increase with dose, but now, with the accumulation of seven more years of follow-up, there seems to be an excess in the very high dose range, particularly for the younger age ATB cohort. Further follow-up is called for to confirm this suggestion.