To investigate the contents of radionuclides in foods marketed in Japan and their daily intakes and exposure doses in adults, we performed market-basket studies concerning radionuclide intakes. The study period was 2003-2005, and the studies were performed in 13 cities in Japan. Foods including drinking water were divided into 14 food groups, and samples were prepared by common cooking procedures. γ-ray emitting nuclides (an artificial radionuclide, radioactive Cs, and natural radionuclides,
40K and U series such as
214Bi, and
212Pb, and Th series) were measured in each food group, and artificial radionuclides,
90Sr and
238U, were measured in a mixed sample of 13 food groups excluding drinking water. The daily intakes in adults were calculated from the concentrations of the radionuclides and mean daily consumption of foods and drinking water. The daily
137Cs and
40K intakes (mBq/person·day) in the 13 cities were 12.5-<79.7 and 57309-95746, respectively. The
90Sr intake from the food groups excluding drinking water was 20.8-53.6, with a mean of 39.2 (mBq/person·day) (deviation of the mean: 23%). Similarly, the daily
238U intake was 5.9-31.1, with a mean of 12.6 (mBq/person·day) (deviation: 60%), showing a more than 5-fold difference between the minimum and maximum values, and there were regional differences. Since the contents of the U series, such as
214Bi and
212Pb, and Th series were lower than the lower detection limits in many samples, their daily intakes were not calculated. Regarding the daily intake of
137Cs from each food group, the intakes from fish and shellfish, milk, meat/eggs, and mushrooms/seaweed tended to be higher. The daily
40K intake from each food group varied among the areas, but the total intake from the 14 food groups was similar in all 13 cities.
40K from these foods accounted for most of the annual effective dose (μSv/person·year) of γ-ray emitting nuclides, and the doses of
40K,
90Sr, and
238U were 130-217, 0.21-0.55, and 0.10-0.51, respectively.
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