Radioactivity concentrations of nuclides of the 232Th and 238U radioactive chains and 40K, 90Sr, 137Cs, and 239+240Pu were surveyed for raw and cooked food of the population in the Red River delta region, Vietnam, using α-, γ-spectrometry, and liquid scintillation counting techniques. The concentration of 40K in the cooked food was the highest compared to those of other radionuclides ranging from (23 ± 5) (rice) to (347 ± 50) Bq kg-1 dw (tofu). The 210Po concentration in the cooked food ranged from its limit of detection (LOD) of 5 mBq kg-1 dw (rice) to (4.0 ± 1.6) Bq kg-1 dw (marine bivalves). The concentrations of other nuclides of the 232Th and 238U chains in the food were low, ranging from LOD of 0.02 Bq kg-1 dw to (1.1 ± 0.3) Bq kg-1 dw. The activity concentrations of 90Sr, 137Cs, and 239+240Pu in the food were minor compared to that of the natural radionuclides. The average annual committed effective dose to adults in the study region was estimated and it ranged from 0.24 to 0.42 mSv a-1 with an average of 0.32 mSv a-1, out of which rice, leafy vegetable, and tofu contributed up to 16.2%, 24.4%, and 21.3%, respectively. The committed effective doses to adults due to ingestion of regular diet in the Red River delta region, Vietnam are within the range determined in other countries worldwide. This finding suggests that Vietnamese food is safe for human consumption with respect to radiation exposure.
Keywords: 232Th and 238U radioactive chain; Annual committed effective dose; Polonium-210; Potassium-40; Red River Delta; Vietnam.