High-sensitivity determination of radioactive cesium in Japanese foodstuffs: 3 years after the Fukushima accident

摘要

We analyzed Cs-134, Cs-137 and K-40 in 96 foodstuffs in supermarkets with high sensitivity over 3 years after Fukushima accident. Milk, yoghurt, rice, tea, salmon, cereal, blueberry, miso, and apples had a trace of Cs-134 and Cs-137 from 10(-3) to 10(0) Bq/kg, however, some mushrooms that were bought in the outer Fukushima prefecture were contaminated by radioactive cesium over the regulatory limit (100 Bq/kg). In view of the Cs-134/Cs-137 radioactivity ratio, we can conclude that Cs-137 detected in remote areas 300 km or more from Fukushima Nuclear power plant contained activity from Pre-Fukushima events such as Chernobyl accident (1986) and atmospheric nuclear explosions (from 1945).