Estimation of Radionuclide Concentrations and Average Annual Committed Effective Dose due to Ingestion for the Population in the Red River Delta, Vietnam

Radioactivity concentrations of nuclides of the Th-232 and U-238 radioactive chains and K-40, Sr-90, Cs-137, and Pu239+240 were surveyed for raw and cooked food of the population in the Red River delta region, Vietnam, using -, -spectrometry, and liquid scintillation counting techniques. The concentration of K-40 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 Po-210 concentration in the cooked food ranged from its limit of detection (LOD) of 5mBqkg(-1)dw (rice) to (4.0 +/- 1.6) Bq kg(-1)dw (marine bivalves). The concentrations of other nuclides of the Th-232 and U-238 chains in the food were low, ranging from LOD of 0.02Bqkg(-1)dw to (1.1 +/- 0.3) Bq kg(-1)dw. The activity concentrations of Sr-90, Cs-137, and Pu239+240 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 0.42mSva(-1) with an average of 0.32mSva(-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.