External radiation dose reconstruction among individuals exposed to fallout from atmospheric nuclear weapons testing at the Semipalatinsk nuclear test site.

External radiation whole-body doses from gamma-emitting radionuclides deposited on the ground were reconstructed for 14,789 individuals exposed to fallout resulting from atmospheric nuclear weapons tests carried out at the Semipalatinsk Nuclear Test Site (SNTS) in Kazakhstan between 1949 and 1962. Dose assessment used the joint U.S.-Russian dosimetry methodology with settlement-specific exposure rate values that were measured or reconstructed, fallout arrival times, individual residential histories of the study participants, and age- and ethnicity-specific occupancy patterns. Estimated whole-body external doses ranged from 0.02 mGy to 595 mGy, with an arithmetic mean (AM) of 82 mGy and a geometric mean (GM) of 35 mGy. The highest doses were observed among 4161 study participants who were exposed to the first test conducted on 29 August 1949 (AM: 180 mGy; GM: 114 mGy). The next highest doses were observed among 6804 individuals exposed to thermonuclear test #4 conducted on 12 August 1953 (AM: 52 mGy; GM: 41 mGy), and among 1820 individuals exposed to test #2 conducted on 24 September 1951 (AM: 34 mGy; GM: 33 mGy). Although uncertainties in the dose estimates were not formally quantified, they were estimated to correspond to a geometric standard deviation between 1.5 and 2.0 for most study participants. The residents around the SNTS represent a valuable resource for evaluating the long-term risks of cancer and non-cancer diseases associated with low-to-moderate radiation exposure doses.