Effects of indoor and outdoor cultivation conditions on 137Cs concentrations in cultivated mushrooms produced after the Fukushima Daiichi Nuclear Power Plant accident

BACKGROUNDRadiocesium (Cs-134 and Cs-137) in mushrooms has been a matter of public concern after the accident at Fukushima Daiichi Nuclear Power Plant. To minimize the internal dose by ingestion of cultivated mushrooms, the Japanese government set a guideline level with respect to the radiocesium concentration in bed-logs and mushroom beds; however, the effects of indoor and outdoor cultivation methods on radiocesium concentrations in cultivated mushrooms were not clear. RESULTSThe effects of indoor and outdoor cultivation on the radiocesium concentrations in mushroom were examined using published food monitoring data. Cs-137 concentration data in Lentinula edodes from the Aizu area in Fukushima Prefecture and seven prefectures outside Fukushima were used for the analysis. No statistically significant Cs-137 concentration differences were found between these two cultivation methods. Using detected Cs-137 data in shiitake, the geometric means from each prefecture were less than one-quarter of the standard limit (100 Bq kg(-1)) for total radiocesium under both cultivation conditions. CONCLUSIONIt was suspected that re-suspended radiocesium might have been taken up by mushrooms or that radiocesium might have been absorbed into the mushrooms from the soil in the outdoor cultures. However, neither effect was significant for cultivated mushrooms in the areas examined. (c) 2016 Society of Chemical Industry