Arsenic, cadmium and lead in sclerotia of Wolfiporia extensa of Yunnan, China

Research Progress on Elements of Wild Edible Mushrooms

Wild edible mushrooms are distributed all over the world and are delicious seasonal foods, rich in polysaccharides, amino acids, vitamins, and other components. At the same time, they contain many essential trace elements and are highly enriched in heavy metals (compared to green plants and cultivated edible mushrooms). Consumers may be exposed to health risks due to excessive heavy metals in the process of consumption. This is also one of the important factors affecting the import and export of edible mushrooms, which is of great concern to consumers and entry and exit inspection and quarantine departments. In this paper, the contents of four essential trace elements of iron, manganese, zinc, and copper and four harmful heavy metals of cadmium, lead, mercury, and arsenic in nearly 400 species of wild edible mushrooms from 10 countries are reviewed. It was found that the factors affecting the elemental content of edible mushrooms are mainly divided into internal and external factors. Internal is mainly the difference in species element-enrichment ability, and external is mainly environmental pollution and geochemical factors. The aim is to provide a reference for the risk assessment of edible mushrooms and their elemental distribution characteristics.

Occurrence, distribution, and associations of essential and non-essential elements in the medicinal and edible fungus "Fuling" from southern China

In Asian countries, the sclerotia of the wild-grown fungus Pachyma hoelen ("Fuling"), have been used as food and as medicinal products for centuries. To close the knowledge gaps about the value and possible environmental impacts, the occurrence, distribution, and associations of a range of elements (Ag, Al, As, Ba, Cd, Co, Cr, Cs, Cu, Li, Mg, Mn, Ni, Pb, Rb, Sb, Sr, Tl, U, V, and Zn) were studied in the inner (core) and outer (shell) morphological parts of the sclerotia from a diverse collection in Southern China. Quality of forest and agricultural soil in terms of a geogenic element source and composition can be considered as the main factor determining the occurrence of minerals in sclerotia through the host wood, largely of Pinus yunnanensis, while the anthropogenic impact (basically at remote rural areas of cultivation) in Southern China was negligible. In general, the mean concentration of each element in the outer part was significantly higher than that in the inner part (t-test, p < 0.01), except for Ag. The concentration of a given element in the outer part tended to have a positive relationship with that in the inner part, except for Cu, Se, Ag, and Zn. The elements in different morphological parts of sclerotia present different relation patterns. Compared to the outer part, there were stronger associations of elements in the inner part, suggesting homeostatic regulation of multiple elements in the inner parts. Further study on the sclerotia, infected wood substrate, and surrounding soil from a range of wild sample collections and intentional cultivation should provide a more complex view and allow assessment of the relationship between minerals and bioactive organic compounds produced by P. hoelen.

On the occurrence, origin, and intake of the nuclides, 210Po and 210Pb, in sclerotia of Wolfiporia cocos collected in China

The dried sclerotium of the fungus Wolfiporia cocos is edible and has medicinal value. This study aimed to understand the accumulation of radioactivity arising from the alpha ²¹⁰Po, and beta-emitting ²¹⁰Pb, in the sclerotium's shell and core and assess a potential effective dose for consumers. Sclerotia were collected in the wild and from cultivars in China's Anhui and Yunnan provinces. The mean values of ²¹⁰Po activity concentration levels were 0.36 Bq kg^-1 dry weight in the core and 12.0 Bq kg^-1 dw in the shell; ²¹⁰Pb activities were 0.43 and 9.84 Bq kg^-1 dw, respectively. The potential effective radiation doses from core layers (as a major raw material of the sclerotium) ranged from 0.13 to 3.43 µSv kg^-1 dw from ²¹⁰Po decay and from 0.11 to 1.52 µSv kg^-1 dw from ²¹⁰Pb decay. Corresponding values for shell ranged from 0.80 to 42.4 for ²¹⁰Po and from 0.53 to 13.6 µSv kg^-1 dw for ²¹⁰Pb. In general, the intake of W. cocos sclerotia varies between consumers, but this would not significantly change the effective radiation doses from ²¹⁰Po and ²¹⁰Pb isotopes. The consumption thus appears to be safe from a radiological protection point of view.

Occurrence, toxicity, and speciation analysis of arsenic in edible mushrooms

Owing to the strong concentration and biotransformation of arsenic, the influence of some edible mushrooms on human health has attracted widespread attention. The toxicity of arsenic greatly depends on its species, so the speciation analysis of arsenic is of critical importance. The aim of the present review is to highlight recent advances in arsenic speciation analysis in edible mushrooms. We summarized the contents and distribution of arsenic species in some edible mushrooms, the methods of sample preparation, and the techniques for their identification and quantification. Stability of the arsenic species during sample pretreatment and storage is also briefly discussed.

Determination of mineral contents of wild Boletus edulis mushroom and its edible safety assessment

This study aimed to determine the contents of main mineral elements of wild Boletus edulis and to assess its edible safety, which may provide scientific evidence for the utilization of this species. Fourteen mineral contents (Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Na, Ni, Sr, V and Zn) in the caps and stipes of B. edulis as well as the corresponding surface soils collected from nine different geographic regions in Yunnan Province, southwest China were determined. The analyses were performed using inductively coupled plasma atomic emission spectrometer (ICP-AES) after microwave digestion. Measurement data were analyzed using variance and Pearson correlation analysis. Edible safety was evaluated according to the provisionally tolerable weekly intake (PTWI) of heavy metals recommended by United Nations Food and Agriculture Organization and World Health Organization (FAO/WHO). Mineral contents were significantly different with the variance of collection areas. B. edulis showed relative abundant contents of Ca, Fe, Mg and Na, followed by Ba, Cr, Cu, Mn and Zn, and the elements with the lower content less were Cd, Co, Ni, Sr and V. The elements accumulation differed significantly in caps and stipes. Among them, Cd and Zn were bioconcentrated (BCF > 1) while others were bioexcluded (BCF < 1). The mineral contents in B. edulis and its surface soil were positively related, indicating that the elements accumulation level was related to soil background. In addition, from the perspective of food safety, if an adult (60 kg) eats 300 g fresh B. edulis per week, the intake of Cd in most of tested mushrooms were lower than PTWI value whereas the Cd intakes in some other samples were higher than this standard. The results indicated that the main mineral contents in B. edulis were significantly different with respect to geographical distribution, and the Cd intake in a few of regions was higher than the acceptable intakes with a potential risk.