Additional contamination of shiitake mushrooms (Lentinula edodes) cultivated on bed-logs in an artificial environment

Abstract Radioactive cesium was released into the environment from the Fukushima Daiichi Nuclear Power Plant of Tokyo Electric Power Company, which was damaged by the Great East Japan Earthquake. The shiitake industry suffered various damages as a result. One type of damage is contamination by radioactive cesium in the cultivation environment, known as ‘additional contamination’. Additional contamination is assumed to be caused by the transfer of radioactive cesium from the soil to the fruiting bodies via the bed-logs. We conducted a 15-month bed-log cultivation in a glasshouse on soil contaminated with radioactive cesium to verify the transfer of radioactive cesium from the soil to the fruiting body. The transfer was verified mainly using stable cesium, but no transfer of radioactive cesium from soil to the fruiting body was observed. This result indicates that additional contamination is caused by other factors.