Distribution and possible dietary intake of radioactive ¹³⁷Cs, ⁴⁰K and ²²⁶Ra with the pantropical mushroom Macrocybe gigantea in SW China

Abstract

There is scarcity of data on contamination with radiocesium (^134/137Cs) of edible mushrooms from the Southwestern Asia. This study aimed to get insight into activity concentration of artificial nuclides ^134/137Cs and natural ⁴⁰K and ²²⁶Ra in mushrooms from Yunnan province, which is major producer in China. The specimens of pantropical mushroom Macrocybe gigantea were collected from the wild and from a farm across Yunnan land in 2012–2013 and analyzed using gamma spectrometry with hyperpure germanium coaxial detector (HPGe). M. gigantea showed low activity concentrations of ¹³⁷Cs (median value for dehydrated caps was 4.5 Bq kg⁻¹ and 5.4 Bq kg⁻¹ for stipes) while ¹³⁴Cs was not detected. Natural radionuclide ⁴⁰K showed 2–3 orders of magnitude greater activity concentration compared to artificial ¹³⁷Cs in M. gigantea. The activity concentrations of ²²⁶Ra from uranium and radium decay series for most of the consignments of M. gigantea examined were below the method's limit of detection. The nominal effective dose equivalent for the Yunnan people from the dietary intake of ¹³⁷Cs was assessed to be below 0.01 μSv per annum on the average, and that from ⁴⁰K to be below 0.1 μSv per annum. Data available for the first time on activity concentrations of ¹³⁷Cs in wild-grown saprobic mushroom from this region of Asia suggest low pollution with radiocesium from fallout there. Hence, the likely health risks from intake of ¹³⁷Cs from cooked M. gigantea are in practice of mushrooms absent for human consumers there. Because of abundance of mushrooms in Yunnan and high significance of the region as producer and exporter a wider study using many species is necessary to fill a gap on possible radioactive contamination and risk to mushroom consumers.

Keywords:

• Forage
• fungi
• gamma emitters
• macromycetes
• radioactivity
• radiocesium

Funding

Part of this study was funded by the National Natural Science Foundation of China (No. 31260496, 31160409).