239,240Pu concentration in contaminated european foods imported to Japan following the Chernobyl accident

In order to consider the foods contamination with artificial nuclides, 239,240Pu, released from the Chernobyl accident, radioactivities of plutonium in imported European foods which exceed the interim intervention level for screening (134Cs+137Cs; 370 Bq/kg) in Japan were determined by alpha-ray spectrometry. Among three spices, one laurel leaf, one savory leaf and one thyme, in 13 food samples, 239,240Pu were found to be in the range of 52 to 85 mBq/kg. The results shows that 239,240Pu/137Cs and 239,240Pu/90Sr radioactivity ratios in those spices are respectively the levels of 10-4-10-5 and 10-3 which are almost equal to the radioactivity ratios in the releases from the Chernobyl reactor. Effective dose equivalent received by the general public was calculated to be 8.9x10-4 mSv. This value is less than 0.1% of the annual effective dose equivalent received from natural sources, 2.4x10-3 Sv. (author)