158 Health Physics exposures The subject of cancer nisks 1s addressed m a companion paper by Land et al (2010) Wehave attempted to collect and use the available data and information to conduct a dose reconstruction m a manner webeheve to be relatively free of mtentional biases To accomplish that, m a companion paper (Beck August 2010, Volume 99, Number 2 doses to the most exposed populations m the northern Marshall Islands immediately downwind from the 1954 Bravo test (James 1964, Lessard et al 1984, 1985) Much of the earher work was reported m a special issue of Health Physics (Simon and Vetter 1997) and focused on fallout radionuchdes determmed to have contributed over 99% of the acute mternal doseat all 32 mhabited and monitoring of the most 1mpacted 1slands and people, developmg land remediation strategies, and assessing contemporary and possible future doses that might be received by mhabitants of certam atolls of the northern Bikim and Enewetak Atolls where the tests were con- ysis has ever been completed on the mtakes and mternal et al 2010), we estimated the deposition densities of 63 ummhabitated atolls of the Marshall Islands, excluding ducted, and developed a method to estimate acute and chronic intakes of radioactive materials from the nuclear tests for representative persons of various age groups at all mhabitedatolls and the related doses to four organs Acute mtakestook place during the period of the trme the fallout was bemg deposited at each atoll Gf durmg the day) or shortly afterwards if the fallout arrived at mght The assumption was made that acute mtakes were pnmarily the result of eatmg superficially-contaminated food, using contammated eating utensils, mgestmg contamination deposited on the hands and face, and to a lesser degree, drmking contammated water (Lessard et al 1985) Followmg the deposition of radionuchdes on the ground, protracted or chrome intakes took place by imgestion but at rates much smaller than those due to the acute mtakes The environmental pathways resultmg in chromic mtakes are substantially different from the direct deposition of fallout on ground surfaces and materials accountng for acute intakes Chromic intakes among Marshallese were primarily a result of consumption of seafood and oflocally grown terrestrial foodstuffs and, to a lesser degree, madvertent consumption of soil (Simon 1998, NCRP 1999) Doses estimated mthis work are atoll and age-group annual and Iifetrme radiation absorbed doses (Gy) to four organs, red bone marrow (RBM), thyroid gland, stomach wall, and colon wall, and presented as best estimates and with 90% uncertamty ranges Doses pertammg to representative persons residmg at every mhabited atoll and for all relevant birth years have been estimated for the analysis of cancer risk (Land et al 2010) In this paper wepresentthe dosimetric fmdmgs for four commumities (Mayuro, Kwayalem, Utrik, and Rongelap) that represent the overall range of doses recetved across the Marshall Islands as well as represent the populations of the two atolls with the largest number of residents (Mayuro, the capital and largest popu- Marshall Islands However, to our knowledge, no analdoses from al] fallout radionuchdes, from all tests, and at all mhabited atolls The primary goal of this publication and the compamon papers was to carry out a compre- hensive dose assessment and cancer risk projection Historical context Of all the Pacific nuclear tests, the 1954 Castle Bravo test at Bikim Atoll caused the most serious exposures Followmg the Bravo detonation on | March 1954, heavy early fallout was unexpectedly deposited on nearby atolls in the Marshall Islands to the east of Bikim begmmmg at about 4 h post-detonation and resultmg m moderate to high radiation exposures to small groups of Marshallese and Americans living or staymg on those atolls 64 Marshallese on Rongelap, 18 Marshallese from Rongelap staying on Sifo Island m Ailinginae Atoll, 159 Marshallese on Utnk Atoll, 28 military weather observ- ers on Rongertk Atoll, and 23 sailors on the Japanese fishing vessel, the Lucky Dragon (see Cronkite et al 1997 and Srmon 1997 for additional hstory) The magmitudes of mterna] doses recetved bythe thyroid gland of the Marshallese and American weather servicemen were not completely understood at the tme of the Bravo test, primarily because there was little experience at estimatimg the many factors that are smportant to the determnation of radiation dose, e g , fission y1elds, atmospheric dispersion and deposition-related factors, quantitative understanding of modes of mtake (inhalation vs mgestion), solubility of different nuclides, doses received per umt activity mtake of each radioiodme,etc The earliest estimates of mternal dose to the nghly exposed Rongelap and Ailmgmae populations were mm a Los Alamos Scientific Laboratory (LASL) memo to the US Atomic Energy Commission (USAEC) (Hams 1954) In that document, a summary of measurements of urmary excretion of "I and several other nuchdes were lation center, and Kwayalem, home to a US muhitary base reported from population pooled urine samples collected As far as we know, there are no publications in the James (1964) estrmated thyroid doses to Rongelap chil- and the secondlargest population center) peer-reviewed literature on mternal doses to all the Marshallese from fallout on a yearly basis from 1948 through 1970 Previous reports focused primarily on from adults at 16, 17, and 19 d post-detonation Later, dren based on the LASL excretion data (Harris 1954), though James mistakenly reported that the LASL pooled urme sample contamed 201% (by volume) from ages