2009 年 55 巻 2 号 p. 192-205
The present study was undertaken to investigate the amounts of artificial radionuclides ingested through the daily diet by inhabitants of Kanagawa Prefecture, Japan. To this end, the level of cesium-137 (137Cs) contained in the daily diets of females (combined samples from 5 females) aged 40-69 living in urban and suburban districts of Kanagawa Prefecture was measured. Furthermore, 11 elements (Ca, Cl, Cr, Cs, Fe, K, Mn, Na, Rb, Sc, and Zn) in the diets were quantified by instrumental neutron activation analysis. The study revealed that the intake of 137Cs increased markedly in 1986, the year the Chernobyl accident occurred, and it tended to decrease gradually thereafter. In recent years, the reduction in the dietary intake of 137Cs has been slowing down. When the intake of nutrients ingested by inhabitants of the two survey areas was compared with the Dietary Reference Intakes for Japanese (2005), the amount ingested in each of the two survey areas approximately satisfied or was slightly lower than the reference levels. Among others, the amount of Ca and Fe ingested in the urban district was particularly low (52 and 64% of the national reference, respectively). For many elements, the amount ingested was greater in the suburban than in the urban district. When the ingredients of the subjects' meals were classified into food groups, the meals prepared by suburban inhabitants were found to be composed of more diverse ingredients, covering all food groups, compared to those prepared by urban inhabitants. The daily food intake was also greater in the suburban district. When the daily dietary samples from individual subjects were analyzed separately, without being combined, both the level of 137Cs and the amount of stable elements contained in the separate samples showed greater variations from day to day than those in the combined samples. There was no correlation between the dietary intake of 137Cs and that of Cs.