Intake of radioactive materials as assessed by the duplicate diet method in Fukushima

A large quantity of radioactive materials was released from Reactor-II of the Fukushima Daiichi Nuclear Power Plant (F-1 NPP). People living in the area affected by the release are concerned about internal exposures from the daily intakes of contaminated foodstuffs. In order to assess whether the people should be concerned, Co-op Fukushima (Consumer Co-operative in Fukushima Prefecture) conducted a broad survey of radiocaesium in daily meals for which local inhabitants voluntarily provided a set of duplicate meals. Analyses by the duplicate diet method were conducted from November 2011 to March 2012 and from June 2012 to September 2012, each covering 100 families throughout the prefecture. Among the 200 meals thus analysed, 12 were found to have (134)Cs and/or (137)Cs concentrations exceeding 1 Bq kg(-1). Even with the largest radiocaesium value in our survey, daily consumption of such meals throughout a year gave an annual committed effective dose that did not exceed 0.1 mSv.