Abstract
We report the results of analyses on translocation frequency in lymphocytes of a-bomb survivors by fluorescence in situ hybridization (FISH) method. This study is expected to provid answers to several questions raised by the past cytogenetic studies using conventional Giemsa staining methods. These questions related to the disparity in radiation dose responses between the two cities—Hiroshima and Nagasaki, and lower dose response of Nagasaki factory workers. Because Hiroshima and Nagasaki survivors were examined at Hiroshima and Nagasaki RERF laboratoey, respectively, previouse study with simple Giemsa staining were not free from laboratory bias. Therefore, the present FISH study conducted exclusively at the Hiroshima Laboratory. To date, 900 Hiroshima and 541 Nagasaki survivors were examined by FISH. Present data are summarized as follows: (a) a wide scatter of individual translocation frequencies was observed when plotted against DS02 doses as seen in the previous Giemsa staining study; (b) the city difference became much smaller now using FISH, and the difference is only marginally significant; (c) Nagasaki factory workers and the peoples exposed in outside but with house shielding in both cities had significantly lower dose responses than people who were exposed in Japanese houses; (d) the reduced intercity difference suggests that the previous city difference by the Giemsa methods was mainly due to different aberration detection rates between Hiroshima and Nagasaki laboratories.
