Letter to Roger Ray September 12, 1984 Page 2 showed excellent agreement. This agreement between measured and predicted levels constitutes an important overall validation of models employed in the predictions -- including physical, biological, and cultural aspects of these models. Publication of this validation was recommended. The accumilation of data and the validation of models in recent years would seem to remove any reluctance te apply applicable U.S. limits to the Marshall Islanders. An area of remaining uncertainty relates to the transuranic elements, principally plutonium and americium, where very limited bioassay data on plutonium excretion yielded much higher radiation dose values than predicted by models. This is not considered a serious complication because the transuranics are not predicted to contribute importantly to the total radiation dose, and analytical problems involving natural polonium in the urine samples seem to offer a plausible explanation of the bioassay problem. This problem is being intensively studied and a resolution may be anticipated within 3 to 6 months -- perhaps sooner. To assist in this, information on plutonium bioassay methods and the Leggett and Moss dosimetric models is being forwarded to Dr. Lessard. With respect to the potential resettlement of Eneu, based on the best current evidence, it stil] seems unlikely that an Eneu resident, consuming a mix of local and imported foods (but no significant quantity from the Island of Bikini), would exceed an exposure of 500 mrem per year. On yours, W. J. Bair, Ph.D. Manager Environment, Health and Safety Research Program WJB: 1m cc: Tom Clark, NVO Participants