Paper ACUTE AND CHRONIC INTAKES OF FALLOUT RADIONUCLIDES BY MARSHALLESE FROM NUCLEAR WEAPONS TESTING AT BIKINI AND ENEWETAK AND RELATED INTERNAL RADIATION DOSES Steven L. Simon,* André Bouville,* Dunstana Melo,* Harold L. Beck,’ and Robert M. Weinstock* available anywhere and were used to makeprojectionsof lifetime cancer risks to the exposed populations, which are presented in a companion paperin this volume. Health Phys. 99(2):157-200; 2010 Abstract—Annualinternalradiation doses resulting from both acute and chronic intakes of all important dose-contributing radionuclides occurring in fallout from nuclear weaponstesting at Bikini and Enewetak from 1946 through 1958 have been estimated for the residents living on all atolls and separate reef islands of the Marshall Islands. Internal radiation absorbed doses to the tissues most at risk to cancer induction (red bone marrow, thyroid, stomach, and colon) have been estimated for representative persons of all population communities for all birth years from 1929 through 1968, and for all years of exposure from 1948 through 1970. The acute intake estimates rely on a model using, as its basis, historical urine bioassay data, for members of the Rongelap Island and Ailinginae communities as well as for Rongerik residents. The model also utilizes fallout times of arrival and radionuclide deposition densities estimated for all tests and all atolls. Acute intakes of 63 radionuclides were estimated for the populations of the 20 inhabited atolls and for the communities that were relocated during the testing years for reasons of safety and decontamination. The model used for chronic intake estimates is based on reported whole-body, urine, and blood counting data for residents of Utrik and Rongelap. Dose conversion coefficients relating intake to organ absorbed dose were developed using internationally accepted models but specifically tailored for intakes of particulate fallout by consideration of literature-based evidence to choose the most appropriate alimentary tract absorption fraction (f,) values. Dose estimates were much higher for the thyroid gland than for red marrow, stomach wall, or colon. The highest thyroid doses to adults were about 7,600 mGy for the people exposed on Rongelap; thyroid doses to adults were muchlower, by a factor of 100 or more, for the people exposed on the populated atolls of Kwajalein and Majuro. Theestimates of radionuclide intake and internal radiation dose to the Marshallese that are presented in this paper are the most complete Key words: dose, internal; fallout; Marshall Islands; nuclear weapons INTRODUCTION INTERNAL RADIATION doses to residents of the Marshall Islands during the years of nuclear testing at Bikini and Enewetak (1946-1958), as well as in later years, were a consequence of inadvertent intake of radioactive materials from nuclear tests that were deposited as fallout. Doses were received both from acute intakes, 1.e., those intakes occurring at the time of fallout or immediately afterwards, and from chronic intakes of residual radioactivity in the environment, i.e., intakes occurring contin- uously for manyyears after deposition. But deriving and understanding the true range of organ doses received by the Marshallese specific to each nuclear test and at each atoll of residence has remained an unmet challenge for many years. Understanding radiation doses to the Marshallese is important for several reasons that include providing to the Marshallese a complete account of the radiation doses they received and the related health consequences, increasing our overall understanding of the health impact of nuclear testing conductedin the past, and increasing our understanding and ability to prepare against fallout events in the future. A companion paper addresses external doses received by representative persons in the Marshall Islands from nuclear testing (Bouville et al. 2010). This paper addresses internal doses. The sum of the internal and * Division of Cancer Epidemiology and Genetics, National Can- cer Institute, National Institutes of Health, Bethesda, MD 20892; * New York City, NY (retried from U.S. DOE); * Consultant, Bethesda, MD. For correspondence contact: Steven L. Simon, National Cancer Institute, National Institutes of Health, 6120 Executive Blvd., Bethesda, MD 20892, or email at ssimon@mail.nih.gov. (Manuscript accepted 5 May 2010) external doses (Simon et al. 2010), when estimated as 0017-9078/10/0 Copyright © 2010 Health Physics Society age-specific annual doses at each atoll, can be used to predict the excess cancer burden that resulted from the DOI: 10.1097/HP.0b013e3181dc4e51 157