Action level for imported food in Japan after the reactor accident at Chernobyl

The nuclear accident at Chernobyl in Apr. 1986 caused a widespread release of radionuclides to environment. As a result of food movement in international trade, it was necessary to decide action level of radionuclides for food imported in Japan. The action level was derived from the following basic principle: Dose equivalent should be less than one third of 0.5 rem/year for whole body exposure. Assuming that the composition of representative radionuclides (90Sr, 134Cs and 137Cs) in imported food are equal to those of fallout in Japan and consumption of internal food products reduces total intake of radionuclides to 35 %, action level indicated by sum of 134Cs and 137Cs concentrations was estimated to be 370 Bq/kg. From Nov. 1986 to Sep. 1987, it was observed that twenty samples in imported food contained radioactivity exceeding the action level. (author)