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Human risks to vanadium from naturally growing edible mushrooms and topsoils across Leicestershire, UK
1 , 2 , 1 , 1 , * 1
1  Leicester School of Allied Health Sciences, De Montfort University, Leicester, LE1 9BH, UK.
2  Departamento de Investigación Agroambiental. IMIDRA. Finca el Encín, Crta. Madrid-Barcelona Km, 38.2, 28800 Alcalá de Henares, Madrid, Spain.
Academic Editor: Joana Amaral

Abstract:

Essentiality of vanadium (V) has been proven for some terrestrial fungi. Thus, some wild mushrooms can accumulate high amounts of this element, such as the poisonous species of Amanita. The aims of our work were: a) to biomonitor V in wild edible mushrooms collected from urban and rural green areas across Leicester, a main city in East Midlands (England); and b) to determine the presence and distribution of V in topsoils to identify potential risks to humans. A total of 34 edible mushrooms were collected as follows: twenty-two Agaricus bitorquis were collected from an open green area close to St Augustine Road, a high traffic area close to the city centre, four Marasmius oreades from Jesse Jackson Park in the northeast of the city, and eight Coprinus atramentarius from Bradgate Park, a 850 acre public park in Charnwood Forest, Leicestershire (northwest of Leicester city). Although C. atramentarius has been described as poisonous, this mushroom species are edible and safe if cooked and if no alcohol is ingested within 2–3 days of eating C. atramentarius. Species identification was confirmed by DNA barcoding using internal transcribed spacer 1/4 primers after extracting DNA from 100 mg of frozen homogenised ground mushroom material using DNeasy Plant Mini Kit®. V was monitored by ICP-MS in cleaned, dried and homogenised mushrooms mineralised with HNO3/H2O2 [LoD=0.062 mg/kg dry weight (dw)]. Significantly higher levels of V were found in C. atramentarius [0.856 (0.175-4.338)] than in the edible mushrooms collected in urban areas [M. oreades 0.305 (<LoD-0.852) and A. bitorquis 0.078 (<LoD-0.187); all data presented as median and range, in mg/kg dw; p-value=2E-07]. In general, the levels of V found were similar to those reported in twelve different edible mushroom species collected in Finland (range reported 0.04-0.33 mg/kg dw), although some of the eight C. atramentarius mushrooms collected presented very high levels of this metal. Thus, despite the health risk quotients calculated (7.06E-10, 2.76E-09, 7.74E-09; for A. bitorquis, M. oreades and C. atramentarius, respectively) suggesting a minimal risk, consuming C. atramentarius mushrooms should be avoided even though if these mushroom species are properly cooked. Moreover, 850 samples were collected (2017-18), which were further processed as composite samples as follows: 26 composite samples were appropriately prepared after mixing topsoil samples collected per location (18 urban, 8 rural), which were further processed in duplicate. V was measured twice in each of the 52 composite samples by ICP-MS after microwave digestion with nitric acid (69%)/chlorhydric acid (37%). V was found in all composites examined (LoD=0.137 mg/kg). Significantly higher levels were found in the rural areas [61.403 (36.029-99.806) vs. 46.279 (25.861-84.653); data presented as median and range, in mg/kg; p-value=3E-05)], which might be attributed to geogenic sources as the enrichment factor for rural topsoils suggest minimal enrichment (EF=0.0046-1.690). Although the levels of V in the topsoils were much higher than the established soil screening value for assessing ecological risks (SSV=2 mg/kg) established by the UK’s Environment Agency. The presence of this metal in the topsoils monitored in the urban and rural areas of Leicestershire would not represent a significant risk for the population, as the hazard quotients for oral, dermal and inhalation exposure to V present in topsoils were much lower than the threshold considered as safe for adults and children. Moreover, the bioconcentration potential of the wild mushroom species collected for V would be minimal as the bioconcentration factors were much lower than the unit in relation to the concentration of V in the underlying topsoils. Although the three wild edible mushroom species monitored in Leicestershire could be considered as bioexcluders of vanadium, the high concentration of this element in some of the mushrooms collected would recommend avoidance of consumption as they may also concentrate other toxic and carcinogenic metals that would add to the identified risk.

Keywords: Vanadium, topsoils, presence and distribution, human risks, Leicestershire.

 
 
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