Daily intakes of radionuclides in Japanese standard diets

Daily intakes of radionuclides in Japanese standard diets were investigated. Food samples were collected from 9 cities of Japan using the market basket method according to the reports of National Nutrition Study in Japan (2000). These samples were categorized the following 14 groups; Group l: rice, rice products; Group 2: grain, seeds, potato; Group 3: sugar, confectionery; Group 4: oils and fats; Group 5: beans; Group 6: fruits; Group 7: green and yellow vegetables; Group 8: other vegetables; mushrooms, seaweed; Group 9: seasoning, drinks; Group 10: fish and shellfish; Group 11: meat, eggs; Group 12: milk, milk products; Group 13: other foods; and Group 14 was drinking water. Each group was homogenized separately after cooking the food materials. Determination of radioactivity was performed by gamma ray spectrometry. The only artificial radionuclide detected from gamma ray spectrometry was 137CS, and its concentrations of each sample were almost less than 0.1 Bq/kg. Strontium-90 and 238U concentrations of the total diet samples were analyzed with chemical separation. The concentrations of 90Sr and 238U were in the range of 0.013-0.031 Bq/kg, 0.0039-0.014 Bq/kg respectively, and a large difference was not found among the concentrations of each nuclide in 9 cities. We would like to estimate internal radiation dose to Japanese population from the dietary intakes of these radionuclides.