Re-estimation of internal dose from natural radionuclides for Chinese adult men.

Based on recent research, related literature data and updated model parameter values, the present internal radiation dose from intakes of radionuclides for Chinese adult men (except for radon and its short-lived decay products) has been re-estimated. Radiation doses obtained by using both direct and indirect approaches have been compared. It is shown that the total annual committed effective dose in Chinese men accounts for approximately 0.43 mSv, 43% higher than the world reference value. The average annual dose from (40)K is quite near to the world reference value, but those from the (238)U-series (with (235)U-series) and (232)Th-series are 2.1- and 3.2-fold higher, respectively. The dose by ingestion is about two orders of magnitude higher than that by inhalation. (40)K is the greatest contributor to the total dose, while, in the decreasing order, (210)Po, (210)Pb, (228)Ra and (14)C are lower. Other radionuclides contribute very little dose ( approximately 2.6%). These results provide a useful basis for clarifying the characteristics of natural radiation exposure and for establishing related reference values for Chinese adult men.