Korean-specific dose coefficients for external environmental exposures: Water contamination

The present study produced a comprehensive dataset of Korean-specific organ equivalent dose coefficients (DCs) for 29 radiosensitive organs and effective DCs for water contamination, thereby completing a series following our previous assessments for soil and air contamination. The DCs were calculated for 25 monoenergetic photons and electrons ranging from 0.01 to 8 MeV using the Mesh-type Reference Korean Phantoms (MRKPs) in combination with the Geant4 Monte Carlo radiation transport code. These monoenergetic DCs were further integrated with nuclear decay data to calculate DCs for 1252 radionuclides of 97 elements. When compared with the ICRP-144 values based on the ICRP-110 voxel phantoms, the Korean-specific effective DCs showed differences of up to 16 % for monoenergetic photons and up to a factor of six for monoenergetic electrons. For representative radionuclides, the Korean-specific values agreed within 1 % for Cs-137/Ba-137m and I-131, whereas an 18 % difference was observed for Sr-90/Y-90. These differences arise from interethnic anatomical variation as well as geometric discrepancies between the phantoms. The DCs based on the Korean reference phantoms would be more reliable in dose assessments for the Korean population under external environmental radiation exposure, contributing to the development of radiological protection and post-exposure response strategies specific to the Korean population.