3 being returned tothese islands. It became apparent that a special vessel was needed. and in 1973 the AEC arranged for the Army to provide an LCU (landingcraft utility) based and maintained at Kwajalein (with AEC funding). This vessel, though small andslow, has the distinct advantage that it can be beached,so that ship-to-shore trans- fer of equipment and personnel by small boatis unnecessary. Three 30-ft air-conditionedtrailers have been placed on the tank deck, one equipped as a “sleeper,” one containing a whole-body counter (shadow-shield lead assembly and elec- tronic equipment), aid oneset up forclinical ex- aminations with a doctor’s office, a small labora- tory, and an x-rayfacility. The LCU with these trailers is now in full use and affords tremendous improvements in the operations. Examinationfacilities at Utirik consist of several Butler-type buildings left by a weather station group. On Rongelap several examinationtrailers have beeninstalled so that the schoolhouse need no longer be used. Examinations mailers have also been installed on Ebeye and Majuro. Major events in the Marshall Islands related to thesurveys, including the political problems of the past few years, are summarized in Appendix 1. Before and after each survey, village meetings have always been held on Rongelap and Uurik to inform the people ofthe objectives of the examinations, the findings, and recommended treatments. Because of the language barrier, the people did not always understand the need for the examinations, or their results. Every effort is now being madeto correct this. Preparation of a questionand-answer booklet on the effects of the fallout and treatment on the Rongelap and Utirik people was recommended by the Congress of Micronesia; such a booklet has been printed at BNLfor the Trust Territory Health Services andis being distributed; it should do muchto correct manyof the former misconceptions (see Appendix 4). During the 20 years covered by these reports drastic changes have occurred in the Marshall Islands District. The population more than doubled from 1948 to 1973, the total going from ~ 10,000 to ~ 25,000. The increases were most dramatic on Majuro (going from 1,200 to 10,300) and on Ebeye (going from 750 to 5,000). On the outerislands the total population changed less (Rongelap, 100 to 167; Uuirik, 126 to 217), but the age distribution became abnormal. Young adults have gravitated to- ward the district centers, and the ‘homeislands” are left with children and old people. A recent survey on Rongelap showedthat of its 167 people, 115 were <15 years old and 30 were >50. The flux is great: during any givenfield trip up to 30 people maybearriving orleaving. The district has opened up to foreign travel. Majuro hasa jet airport, paved roads,electricity, and telephones. Expectations are rising, and when public services fail to keep pace with increasing demand. dissatisfaction is more vocal. ~":e atmospheric bomb tests ended in 1958. Kwajalein was abandoned as a Navy Base in 1960 and was made part of the Army’s missile test range. For the visiting medical teams, loss of Navy assistance in transportation has increased the logistic problems, but the continuing supportof the ArmyBasehas been invaluable. The people of Rongelap and Utirik have always been most friendly and cordial to the medical team. Except for political interference with the 1972 examinations, the people have always been cooperative. ll. Initial Findings A. DOSE ASSESSMENT 1. Source The radiation exposure of the Marshallese was due entirely to fallout, since the detonation site was too far awayfor thermal, blast, or direct irradiation effects. (In constrast, direct effects were re- sponsible for all the injuries from the atomic bombs in Hiroshima and Nagasaki, with little or nofallout.) The fireball from the 1954 Bravo device, detonated from a tower, touched the surface of the earth at Bikini, and large amounts of material were drawn up and mixed with fission products in the bombcloud. Because of an unpredicted shift in the winds in the upper atmosphere,fallout was deposited in a cigar-shaped area 20 to 40 miles wide extending ~ 200 miles to the east of Bikini (see Figure 1). The radioactivity was duetofission products and some neutron-inducedisotopes; the fallout containedlittle fissile material. The radiation was therefore almost entirely from gamma andbeta rays of varying energy from numerous fission radioisotopes. The time after detonation whenfallout began was estimated as 4 to 6 hr at Rongelap, ~7 hr at Rongerik, and 22 hr at Utirik