Metals Transfer in Mushroom Tricholoma matsutake from Regional High Geochemical Background Areas: Environmental Influences and Human Health Risk

Wild-grown edible mushrooms are important in world diets and are also efficient metal accumulators. Yunnan, Southwest China, is the main producing region, with typically high levels of geochemical metals. The environmental factors, bioaccumulation, distribution and human health risks of metals were examined in paired soil and Tricholoma matsutake (n = 54). T. matsutake grows on acidified soils (pH = 3.95–6.56), and metals show a strong heterogeneity, with Fe, Mn, Zn and Cu in the ranges of 16–201, 0.046–8.58 g kg−1, and 22.6–215, 3.7–155 mg kg−1. High soil Fe content led to great accumulation in T. matsutake (0.24–18.8 g kg−1). However, though the soil Mn content was higher than that of Zn and Cu, their concentrations in T. matsutake were comparable (21.1–487 vs. 38.7–329 and 24.9–217 mg kg−1). This suggested that T. matsutake prefers to accumulate Zn and Cu compared to Mn, and this is supported by the bioaccumulation factors (BAFs = 0.32–17.1 vs. 0.006–1.69). Fe was mainly stored in stipes, while Mn, Zn and Cu were stored in caps, and the translocation factors (TFs) were 0.58 vs. 1.28–1.94. Therefore, stipe Fe showed the highest health risk index (HRI) at 1.28–26.9, followed by cap Cu (1.01–2.33), while 98–100% of the Mn and Zn were risk-free. The higher concentration and greater risk of Fe was attributed to the significant effect of soil Fe content (R = 0.34) and soil pH (R = −0.57). This study suggested that Fe, as an essential mineral, may exert toxic effects via the consumption of T. matsutake from high geochemical background areas.