4O1Ous BL 5203 RADIATION LEUKFMOGENESIS: AN ANALYSIS OP THE PROBLEM,* CUSC9 B. P, Cronkite, M. D,, W. Moloney,M. D, and ¥, P, Bond, M. D., Ph. D. (Medical Research Center, Brookhaven National Laboratory, Upton, N.Y.) “ — Leukemia induction following known exposure to ionizing radiation was studied in the reports of Japanese irradiated at Hiroshima and Nagasski, patients irradiated therapeutically for ankylosing spondylitis, children ex- BEST COPY AVAILABLE posed over the thymic region, prenatal exposure from diagnostic pelvic x-cays, patients irradiated therapeutically in various clinical conditions, and individuals exposed occupationally to x-radiation, The results, in conjunc- tion with animal data, indicate clearly that leukemia is a consequence in a email percentage of individuals exposed to large doses of radiation delivered to a sizeable portion of the body. Only two sets of data, that from Japan and that from patients irradiated for ankylosing spondylitis, are suitable for the investigation of possible dose effect relationships, A plot of the incidence of leukemia versus dose for the exposed Japanese is shown in ure 1, PFig- The formidable difficulties in dosimetry, particularly in a mixed gamma-neutron field are discussed. In Figure 2, the case reporta of leukemia in a closed ageing population of exposed Japanese as a function of tine following the bomb detonation is presented. The incidence appears to be falling, The following conclusions are made: following a single dose exposure of man, the instance of leukemia appeared to be approximateiy linear with dose at dose levels of perhaps 100 r equivalent or greater, The * Research supported by the U. S, Atomic Coomisaion, merositery ** Boston City Hospital, Boston, Massachusetts, COLLECTION SZ4AKS4ALL The Medical Research Center 5607 1a | Brookhaven National Laboratory Upton, L. L, New York — 2V4 RECORDS ISLANDS BOXNe, LEQKAL DEPT. PUBL CATION FeLoeR 22-24 7-536

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