vis 4 . 4 a Bae Me et | 4 rr _ 3NL-28939 Thyroid Absoroed Dose Assessment for Rongelap and Utirik Resicents E.T. Lessard, J.R. Naidu, &.P. Miltenberger 3rooknaven National Laboratory Satety and Environmental Protection Division Upton, New York & ACOSO) 11973 N.A. Greenhouse University of California Lawrence Berkeley Laboratory Berkeley, California 94720 te L.V. saplan Brookhaven Summer Studene Program Brookhaven National Laboratory and Yale University ABSTRACT The internal thyroid absorbed dose from Castle Bravo fallout aftfecrsng Rongelap and Ucirik Acolls, Marshall Islands, incgependent approaches encompassing 1) is reassessed using che single poagled urine radio- chemical analysis of March 1954 and currence uptake, retention and excrerion models, 2) airborne concentrations and areal activities of the tfodine isotopes derived from historic soil samples and, 3) atrborne concentrations and areal activities of the tfodine isotopes derived from weather data obtained during the Cthermonuclear test experiment at Bikini Atoll and currence fallout deposition models. Factors such as solubiliry of tfodine isotopes, the possible contribution from neutron induced activicyv, the impace of thy- roid seekers other than lodine tsotopes on dose, and confidence levels for Va.ues of derived quantities such as airborne activity concentracions are also considered. Additionally, these thyroid absorbed dose estimates are compared to the tncidence of thyroid nodules reported for the accidentcally exposed people. Aesearch carried our under che auspice of che U. under Contract No. DE-Acd2-746CHO9016. S. Departmenc of Energy