Cadmium in the wild edible mushroom species of Agaricus bitorquis in Leicester, UK

Abstract

Background and Aim: Consumption of urban garden products is increasing despite the risks that they can represent due to high urban contamination. Effects of urbanisation in wild edible mushrooms are scarce. The aim was to assess the risks to cadmium (Cd) present in wild edible mushrooms Agaricus bitorquis collected in Leicester (UK). Methods: 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®. Cd was monitored by ICP-MS in cleaned, dried and homogenised mushrooms’ caps and stipes mineralised with HNO3/H2O2 [LoD=0.081 mg/kg dry weight (dw)]. Results: Cd was detected in all samples, with significantly higher levels in caps (p<0.001), median and ranges are provided in mg/kg dw: 3.878 (2.213-6.598) vs. 2.068 (0.899-3.679). Concentrations were similar to those recently reported in different species of the genus Agaricus collected in urban habitats within Berlin (Germany; <0.1-32.7 mg/kg DW), but much higher than the reported in sixteen A. bisporus (median 0.2 mg/kg DW) cultivated in high traffic areas within Berlin. All caps monitored exceeded the established maximum concentration limit for Cd in Europe (0.2 mg/kg wet weight, approximately 2 mg/kg dw), in line with the high accumulative metal capability described in the literature for Agaricus spp. Non-carcinogenic health risks in adults and children for Cd in the monitored mushrooms were 3.16E-07 and 1.47E-09, respectively. Conclusions: Our results would suggest potential contamination by Cd in the inner city of Leicester that should be further investigated to protect human health. Although non-carcinogenic risks characterised for Cd were negligible, consumption of wild edible species should be limited and substituted by cultivated mushrooms when possible.