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Lead in wild edible mushroom species in Leicester, England.
1 , 1 , 1 , 2 , * 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: Vito Verardo


Consumption of urban garden products, including edible mushrooms, can contribute to local food security, and is increasing all over the world despite the risks that they can represent due to anthropogenic contamination. Recent systematic reviews have reported a significant toxic risk to those that consume wild edible mushrooms, including adults and children, highlighting a potential public health risk in England that has been little explored. Moreover, evidence of the impact of urbanisation, economic development and growth on wild edible mushrooms in UK urban environments is scarce. The aim was to assess the risks from lead (Pb) present in wild edible mushrooms of the species Agaricus bitorquis collected in Leicester city (England), as well as in urban topsoils, to evaluate the environmental presence and distribution of this contaminant. Twenty-two A. bitorquis mushrooms were collected from an open green area close to St Augustine Road, a high traffic area within Leicester. 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®. Pb was monitored by ICP-MS in cleaned, dried and homogenised mushroom caps and stipes mineralised with HNO3/H2O2 [LoD=0.872 mg/kg dry weight (dw)]. Moreover, 450 topsoil samples were collected from 18 urban parks and green areas across Leicester, which were appropriately prepared, pulverised, pooled together and thoroughly homogenised on a motorised rotating mixer to be further processed as composite samples per park in duplicate. Pb was measured in duplicate in each of the 36 composite sample also by ICP-MS after acid digestion with nitric acid (69%) and chlorhydric acid (37%) in a microwave system. Pb was found in all composites examined (LoD=0.698 mg/kg) and in the collected mushrooms. Levels of this metal were significantly higher in the mushroom caps (p-value=3E-05), median and ranges are provided in mg/kg dw: 2.461 (1.806-6.664) vs. 1.579 (0.988-4.223). Concentrations were in general lower to those recently reported in different species of the genus Agaricus collected in urban habitats within Berlin (Germany; <0.1-51.0 mg/kg DW). However, the levels of Pb detected were much higher than those reported in sixteen A. bisporus (median <1.0 mg/kg DW) specifically cultivated in high traffic areas in the inner city of Berlin, suggesting that Leicester’s St Augustine Road presents a heavy volume of traffic that should be further explored to prevent risks to Pb exposure, which is highly persistent in the environment. All caps monitored exceeded the established maximum concentration limit for Pb in cultivated mushrooms in the European Union (0.3 mg/kg wet weight, approximately 3 mg/kg dw), in line with the high accumulative metal capability described in the literature for Agaricus spp. However, the consumption of the monitored wild mushrooms represents a minimal risk to Pb, as the hazard quotients were much lower than the established threshold in both adults (5.72E-08) and children (2.67E-07). Moreover, the levels of Pb detected in Leicester topsoils (data presented as median and 95% CI, in mg/kg): 102.805 (84.335-110.625), would not represent a risk for the population for any route (oral, inhalation and dermal), although a wide distribution of this metal was observed. Thus, Leicester’s urban region could require remediation, as the levels of this metal exceed the Regulatory Guidance Value of 80 mg/kg established by the UK Environment Agency. Although non-carcinogenic risks characterised for Pb were negligible in the monitored mushroom, high consumption of wild green edibles in Leicester’s city should be limited as there are multiple additional sources of Pb and other metals, and substituted by cultivated edibles when possible.

Keywords: Lead; wild mushrooms; edible; human risks; urban contamination