INTRODUCTION The fallout on the Marshall Island atolls of Rongelap, Rongerik, Ailinginae, and Utirik from the first shot of the series beginning 1 March 1954 created an initial emergency during which the gathering of data was of secondary inportence, This fundamental fact has resulted in uncertainty in all attempts to reconstruct the circumstanees of. the event. Calculation of the external doses received by the exposed.” cet , individuals has required that availabie information be supplemented assumptions, Much of the information itself was necessarily more in r ; ae dicative than exact, In spite of these difficuities, the cooperation¥ of many individuals and groups made it possible to develop a fairly *. consistent estimate of external gamma dosage, although the question of a beta exposure must remain m.stly unanswered, It has been assumed that no significant neutron or alpha particle exposure occurred, This, the main consideration in this report is the total body gamma radiation exposure, Internal doses from inhaled or ingested material have been discussed elsewhere (Reference 1), ‘Data which form the basis of the analysis were furnished by sever- al sources which are listed in the References, These represent measurements made both in the field and in the laboratory in the period immediately following the exposure, Later information has also been included wherever it was available, A summary of these results appears in Reference 16, which covers the biological and medical aspects of the incident, Saab weee rs CHAPTER 1