PROTRACTED EXPOSURE TO FALLOUT: THE RONGELAP AND UTIRIK EXPERIENCE E.T. Lessard, R.P. Miltenberger, S.H. Cohn, S.V. Musolino and R.A. Conard Brookhaven National Laboratory Upton, New York 11973 ABSTRACT From June 1946 to August 1958, the U.S. Department of Defense and Atomic Energy Commission conducted nuclear weapons tests in the Northern Marshall Islands. On March 1, 1954, BRAVO, an aboveground test in the Castle series, produced high levels of radioactive material, some of which subsequently fell on Rongelap and Utirik Atolls due to an unexpected wind shift. On March 3, 1954, the inhabitants of these atolls were moved out of the affected area. They were later returned, Comprehen- to Utirik in June 1954 and to Rongelap in June 1957. sive environmental and personnel radiological monitoring programs were initiated in the mid 1950's by Brookhaven National Laboratory to ensure that body burdens of the exposed Marshallese subjects remained within Atomic Energy Commission guidelines. Their body-burden histories and calculated activity ingestion rate patterns post return are presented along with estimates of internal committed effective dose equivalents. External exposure data are also included. In addi- tion, relationships between body burden or urine activity concentration and declining continuous intake were developed. are: The implications of these studies