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

Abstract

We analyzed 134Cs, 137Cs and 40K 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 134Cs and 137Cs from 10−3 to 100 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 134Cs/137Cs radioactivity ratio, we can conclude that 137Cs 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).