112 Health Physics national capital today and was home to about one-third of the population of the southern atolls m 1958, while the mid-latitude atolls are best represented by Kwayalem, which was home to about one-quarter of the total Marshall Islands population during the testmg years Our radiological findmgs for the southern atolls and midlatitudeatolls along with ourradiological findings for the Utnk commumty and for the Rongelap Island commumity (both from the northern atolls) capture the range of exposures received by Marshallese at all atolls In the case of Utrk and Rongelap, we define the “community” to be those exposed to fallout from the Bravo test on Utnk and Rongelap, respectively, and who were evacuated after the Bravo test Our findings illustrate the geographic pattern as well as provide atoll and atoll- group estimates of contammation, organ dose, and cancer risk as well as the dependence on age at exposure Fallout activity deposited on the ground As discussed m Beck et al (2010), a complete review of various lustorical and contemporary deposition-related data, some available only m gray literature (eg, governmentlaboratory reports and mternal agency and laboratory memoranda, supplemented by meteorological analyses) was used to make judgments regarding whichtests deposited fallout m the Marshall Islands and to estimatefallout deposition density and fallout transit times, otherwsie known as times-of-arrival (TOAs) In some mstances, tt was necessary to use the results of a well-established model of atmospheric transport and deposition (Moroz et al 2010) to corroborate or contradict our mitial assumptionson the occurrence of fallout on particularatolls after certain tests The various types of data reviewed for August 2010, Volume 99, Number 2 “Cs activities remammg m the soil as measured by imvestigators in 1978 (Tipton and Meibaum 1981, Robison et al 1997) and m 1991-1993 (Simon and Graham 1997) This comparison was used to demonstrate the validity of our estimatesoftotal '”Cs deposition density Ouratoll-specific cumulative '*’Cs estimates were found to be in excellent agreement with contemporary measure- ments of °’Cs m soil (Beck et al 2010) Our estimates for the °’Cs deposition density and for the corresponding TOAat eachatoll and for each of 20 mdividual tests are presented m tabular form by Beck et al (2010) Ourbest estimates of the cumulative "Cs deposition density from all tests, with 90% uncertamty ranges, are presented im Table 5 and the geographic pattern of total fallout deposition 1s illustrated m Fig 2 The cumulative "’Cs deposition densites are much greater on northern atolls (e g , Rongelap and Rongerik) than on mid-latitude atolls (e g , Kwayalem) or southern atolls (eg, Mayuro) Table 5, as can be noted, also provides estimates of deposition separately for southern and northern islands in Kwayjalem Atoll and m Rongelap Atoll The deposition densities differed by about 20% between south and north islands of Kwayalem but more than three trmes between islands of south and north Rongelap Atoll (Table 5), reflectmg differences in deposition due either to the large size of the atoll (Kwayalem), or, m the case of Rongelap, to the position of the Bravo debnis cloud trajectory relative to location of individual 1slands mtheatoll The estimates of radionuclide deposition density, fractionation, and transit trmes reported m Beck et al (2010) allowed estrmations of both external and internal dose to representative persons as described m companion estimating deposition mcluded measurements of “’Cs papers contemporary), historical measurements of exposure rate followmg imdividual tests derived from aerial surveys, ground surveys and contmuous-reading monitormg de- Radiation doses and other radionuclides m soi (both historical and vices (strrp-chart recorders), and historical measurements of beta activity collected on gummed film durmg the years of nuclear testing As noted earlier, the estrmated doses came from three sources of exposure (1) external 1rradiation from fallout deposited on the ground, (2) mternal irradiation from acute radionuchde mtakes immediately or soon after deposition of fallout from each test, and (3) mternal For each atoll, fallout TOAs and the estimated irradiation from chrome intakes of radionuchdes resultimg from the contmuous presence of long-hved radionuchdes m the environment of ***9py Examples of deposition densities of 24 of External doses. The doses from external 1rradiation arose from gamma rays emitted during radioactive decay of the fallout radionuchdes durmg the passage of the radioactive cloud or after deposition on the ground Doses received during the passage of the radioactive cloud are generally msignificant compared to those dehvered after deposition of fallout on the ground Exposure durmg cloud passage was implicitly included fractionation of fallout were used to estrmate deposition density for 63 activation and fission products from each nucleartest, plus the cumulative deposition overall tests these radionuchdes are presented m Beck et al (2010) The estimated total '*’Cs activities deposited byall tests from this analysis, after appropriate decay to account for the effective decay rate (radiological plus weathermg) m the Marshall Islands and a correction for global fallout from non-Marshall Islands tests, were compared with contemporary measurements of the total