Mercury in traditionally foraged species of fungi (macromycetes) from the karst area across Yunnan province in China

Abstract

Abstract The objective of this study is to better quantify the occurrence, intake, and potential risk from Hg in fungi traditionally foraged in SW China. The concentrations and intakes of Hg were measured from 42 species including a “hard” flesh type polypore fungi and a” soft” flesh type edible species that are used in traditional herbal medicine, collected during the period 2011–2017. Three profiles of forest topsoil from the Zhenyuan site in 2015 and Changning and Dulong sites in 2016 were also investigated. The concentrations of Hg in composite samples of polypore fungi were usually below 0.1 mg kg−1 dry weight (dw) but higher levels, 0.11 ± 0.01 and 0.24 ± 0.00 mg kg−1 dw, were noted in Ganoderma applanatum and Amauroderma niger respectively, both from the Nujiang site near the town of Lanping in NW Yunnan. Hg concentrations in Boletaceae species were usually well above 1.0 mg kg−1 dw and as high as 10 mg kg−1 dw. The quality of the mushrooms in this study in view of contamination with Hg showed a complex picture. The “worst case” estimations showed probable intake of Hg from 0.006 μg kg−1 body mass (bm) (“hard” type flesh) to 0.25 μg kg−1 bm (“soft” flesh) on a daily basis for capsulated products, from 17 to 83 μg kg−1 bm (“soft” flesh) in a meal (“hard” type flesh mushrooms are not cooked while used in traditional herbal medicine after processing), and from 0.042 to 1.7 and 120 to 580 μg kg−1 bm on a weekly basis, respectively. Graphical abstract Key points • Polypore species were slightly contaminated with Hg. • Hg maximal content in the polypore was < 0.25 mg kg−1dry weight. • Many species from Boletaceae family in Yunnan showed elevated Hg. • Locals who often eat Boletus may take Hg at a dose above the daily reference dose.