Su illance of Facilities and Sit Dose Reassessment for Populations on Rongelap and Project Title: Utirik Following Exposure to Fallout from the BRAVO Incident (March 1, 13. Publications: 14. Scooe: (a) 1954) RK-01-05-02-3 None 200 Word Summary: Incidences of thyroid nodules, benign and malig- nant, in the exposed populations of Utirik and Rongelap has indicated critical differences in correspondence between nodule incidence and thyroid dose for the two populations. The estimated external dose received from the time fallout began to the time of evacuation shows that the Rongelap population received ‘an external dose (175 rads) which was about thirteen times that for the Utirik .population (14 rads), and the thyroid dose was about ten times Larger, whereas the incidence of thyroid nodules in the two populations were not significantly different. A preliminary study. has indicated that the critical area of investigation that could shed light is the period during fallout and evacuation for both the islands. In addition, the fact that the Utirik population returned within 120 days following evacuation, whereas the Rongelap population returned only after three years, requires that we look closely at the Utirik population in terms of a longer exposure period, both internal and external. Further studies would, therefore, have to concentrate on, the reexamination of all available data in reports issued by various agencies during that period, consultations with scientific personnel involved at that time, identifying the areas of uncertainty, and using appropriate computer programs to analyze the ‘data. The end result will enable us to look for correlations between the incidence of thyroid nodules and the reassessed dose estimates. 15. Relationship to Other Projects: (a) This study will Help establish dose estimates from the time of the incident to the present, and will complement the aerial survey, for extemal radiation measurements, over these islands, which is scheduled soon. Together they should present a reliable picture of doses received by the populations and also enable dose estimates to be projected into the future. (b) This study will also be in close conjunction with the programs of Continued collaboration with the University of the BNL Medical Survey Team. ‘Washington, Laboratory of Radiation Ecology, in the area of environmental radioactivity will be maintained. 16. Technical Progress in FY 1977: Preliminary literature search and consultations with Dr. University of California, have been completed. G. A. Sondhaus, This has resulted in defining areas of uncertainty in information and establishing the procedural steps that should be carried out towards elucidating this problem. (See Continuation Sheet) aus so1i205