CHAPTER 1 ARE OE PO REI OE TTD one INTRODUCTION 1.1 OBJECTIVES The present medical resurvey was organized as the first of a contemplated series designed to provide long-term medical examinations of the Marshallese people exposed to radiation from fallout during Operation CASTLE. 1.2 BACKGROUND Following the detonation of a thermonuclear device on Bikini Atoll on 1 March, 1954, 28 Americans on Rongertk Atoll and 239 Marshallese (64 on Rongelap, 18 on Ailinginae, and 157 on Utirik) were exposed to significant amovnts of radiation from fallout. These individuals were evacuated to Kwajalein, where they were cared for during the acute period following exposure by a special medical team comrosedof individuals from the Naval Medical Research Institute (NP‘RI) in Bethesda and in the U.S, Naval Radiological Defense Laboratory (NRDL) in San Francisco. A report of medical findings has been issued as an Operation CASTLE report.! The present report is concerned with the medica} status 6 months later of the Marshallese people wha received the highest estimated dose of gamma radiation, the Rongelap and Ailinginae groups.* The Rongelap group was exposed to an estimated 175 r of gamma radiation, ciilculated from dose rates measured free in air, over a period uf approximately 46 hr. The Ailinginae group received an estimated 69 r of gamma radiation over approximately 54 hr. Both groups received additional beta radiation to exposed skin areas. All findings were more severe in the Rongelap than in the Ailinginae group. These findings are reviewed later in the report. Because of the continuing hazard from radiation on their homeatolls, the Rongelap and Alilinginae people were not returned to their homes after observation at Kwajalein. Instead, they were moved to Majuro Atoll, the Trust Territory Headquarters for the Marshall Islands. Housing was furnished them on Ijij Island (pronounced “edgit”), 10 minutes by boat from the Trust Territory Headquarters, where they were residing at the time of the present examinations. *The Utirik people, who received comparatively slight exposure, were returned to their homeatoll following observation at Kwajalein and were not examined during the present resurvey. The exposed Americans had been returned to their duty stations in the Unitec States.