i 4 Nv ls tg eT =v tae rr . 3NL=22939 a mH Thvroic Absorsed Dose Assessment for Rongelap and Utirik Residents -t. Lessard, J.R. Naidu, 8.2. Miltenberzger 3reoknaven National Laboratory Safety and Environmental Procection Division Upcon, New York 11973 & N.A. Greenhouse University orf California Lawrence Berkeley Laboratory Berkeley, California 947290 & L.V. Kaplan Brookhaven Summer Studente Program 3rookhaven National Laboratory and Yale University ABSTRACT The internal thyroid absorbed dose From Castle Bravo fallout affeccsng Rongelap and Utirik Atolls, Marshall Islands, sidecendent approaches encompassing 1) is reassessed using che single zooled urine radio- chemical analysis of March 1954 and currence uptake, recention and excrecion. models, 2) airborne concentrations and areal activities of the todine isotopes derived from historic soil samples and, 3) and areal activities of adrborne concentrations the todine tsotopes derived from weather cata ob~ tained during che thermonuclear test experiment at Bikini Atoll and current tallout deposicion models. Factors such as solubility of fodine isotopes, the possible contribution from neucron induced activity, the impace of thyroid seekers other than iodine tsotopes on dose, and confidence levels for values of derived quantities such as airborne activity concentrations are also considered. Additionally, these thyroid absorbed dose estimates are compared to the incidence of thyroid nodules reported for che accidencaliy exposed people. 2esearch carried ouc under the auspice of the U. under Contract No. DE-AC92-74CHOO016. S. Departmenc of Energy