140 Health Physics August 2010, Volume 99, Number 2 Table 10. Sum of deposition densities (kBq m~’) from all tests for 24 selected radionuclidesat four atolls. All are fission products unless otherwise noted. Atoll Nuclide Half-life Ret Sr Sr Py By Zr Mo B8Ru WRU BimTe BY Te ey 137 By BICs MOTa Ma 41Ce 'BCe Ce MSpr 2°p* 239+0Dy 2.7a 51d 29a 3.5h 10h 64d 66h 39d 370d 30h 8.0d 78h 2.3h 21h 6.6h 30a 1.7d 3.9h 33d 33h 280 d 6.0h 24d 24,000/6,600 a Majuro 1.8 2.2 6.9 5.8 2.1 1.5 1.6 1.8 4.0 2.4 1.3 2.4 2.5 2.5 1.7 2.0 9.0 7.0 3.8 1.1 2.0 3.0 9.1 7.2 x X X x X X x x x X x x Xx X X x X X X x x x x xX 107! 10° 107! 10° 10° 10° 10° 10° 10! 10° 10° 10° 10° 10° 10° 10° 10° 10° 10° 10° 10! 10! 10° 107 Kwajalein (S) 3.1 3.5 1.2 8.3 2.7 2.5 4.0 2.0 7.0 9.4 2.5 5.7 5.9 1.3 4.6 3.6 1.1 8.5 6.4 3.9 3.5 1.0 2.4 6.6 x X x X X X x X x X X X x xX X X X X X x X X x X 107! 10° 10° 10° 10° 10° 10° 10° 10! 10° 10° 10° 10° 10! 10° 10° 10° 10° 10° 10° 10! 10° 10+ 10° Utrik 4.7 x 3.7 X 1.1 x 3.3 X 8.1 x 4.2 x 7.3 X 3.0 X 6.1 X 1.1 x 2.3 x 5.7 x 5.8 < 1.7 x 8.5 x 2.9 x 8.2 x 2.5 X 7.8 X 8.1 x 5.3 X 3.8 X 44x 3.5 x 10° 10 10! 104 10° 10° 10+ 10! 10° 104 104 10° 10* 10° 104 10! 10° 104 10° 10° 10° 104 10° 10° Rongelap Island 4.2 2.8 7.5 2.7 2.1 3.9 7.6 1.8 4.3 1.1 1.7 4.6 4.7 1.9 2.7 1.8 3.2 3.3 4.6 1.0 4.7 2.1 4.8 1.6 x 10! x 10+ X10! X 10° x 10° x 10° X 10° X 10° x 10° X 10° X 10° xX 10° X 10° x 10° X 10° X 10° x 10° X 10° X 10+ x 10° X 10° X 10° x 10° x 10! “Activation product. Previous estimates of fallout deposition in the Marshall Islands based only on contemporary measurements of '°’Cs in the soil generally underestimated fallout deposition due to considering only physical decay and neglecting the loss of '°’Cs from the soil horizon over time. radionuclidesin fallout were estimated based on atom ratios derived for a TN or non-TNtest as a function of fractionation and the estimates of fallout transit time. Two companion papers present estimates of radiation doses to Marshallese from external irradiation (Bouville et al. 2010) and from internal irradiation (Simon et al. 2010b) Deposition of '°’Cs, one of the more important of the moderately long-lived nuclides, and representative of the that are based on the deposition densities reported here. total fallout deposited, varied considerably over the Mar- Estimates of radiation-induced cancers derived from the shall Islands, but the atolls can be grouped into four groups of similar levels of contamination. Atolls south of Kwajalein, but including Ujae, received cumulative deposition of only few times that of global fallout, in the range of one to three kBq m~. Seven mid-latitude atolls (Kwajalein and others) received slightly higher cumulative deposition, aboutthree to eight times the global fallout deposition. Utrik received considerably higher deposition, about 30 kBq m’, while Rongelap Island received about 180 kBg m*, equivalent to 200 times the global fallout deposition. In the southern and mid-latitude atolls of the Marshall Islands (inclusive and south of Kwajalein), the Romeotest contributed the largest fraction of the total deposition dose estimates are presented in a third companion paper (Landet al. 2010). Acknowledgments—This work was supported by the Intra-Agency agreement between the National Institute of Allergy and Infectious Diseases and the National Cancer Institute, NIAID agreement #Y2-Al-5077 and NCI agreement #Y3-CO-5117. The authors are indebted to several individuals whose analyses and research have made substantial contributions to this work. They include William Robison for various data and publications on measurements made in the Marshall Islands and Dunstana Melo for her review of drafts of the paper, as well as other scientists who have added to our understanding of the contamination and consequences in the Marshall Islands through their scientific publications, many of which are cited here. density of '°’Cs. At atolls north of Kwajalein, the Bravotest contributed the largest fraction of the total deposition REFERENCES Yankee contributed the largest fraction. Timesof transit for fallout to reach atolls varied from as short as 4h for Bravo fallout to reach Ailinginae to about 170 h for Union fallout to reach Kili Island. All important Beck HL, dePlanque G. Theradiationfield in air due to distributed gamma-ray sources in the ground. New York: U.S. Atomic Energy Commission, New York Operations Office; Health and density of '’Cs. In the mid-latitude region (Kwajalein), Safety Laboratory Report HASL-195; 1968. Available at: https://www.osti.gov/opennet/.