Artificial (137Cs) and natural (40K) radioactivity and total potassium in medicinal fungi from Yunnan in China.

Evaluated has been radioactive contamination with 137Cs in parallel to occurrence of 40K and total K in 31 species of medicinal mushrooms from Yunnan, China. We chose species that were not previously studied. The activity concentrations of 137Cs in the medicinal fungi in this study were low. The maximum values were 54 ± 4 Bq kg-1 dry biomass (db) in caps and 48 ± 5 Bq kg-1 db in stipes of saprotrophic fungus Gerronema xanthophyllum from the family of Tricholomataceae. Mushrooms with relatively higher activity concentrations of 40K were among the non-polypore species but certain species from the genus Ganoderma such as G. applanatum, G. capense, G. philippii and G. sinense showed 40K in the higher range of 900 ± 240 to 1400 ± 340 Bq kg-1 db. The concentrations of total K in the fungal materials in this study were in the range from 2.9 ± 6.5 g kg-1 db in Fomes rufolaccatus to 110 ± 6 g kg-1 db in G. xanthophyllum. The species studied, which represented both some popular wood-decaying polypore fungi but also terrestrial forms from the herbal medicine of China, can be considered as little contaminated with 137Cs and potentially good source of leachable K in extract and decoction or as a powdered form in capsules.