Uloma A. Ihugba¹, Chris O. Nwoko^1,, Feechi R. Tony-Njoku¹, Adaeze A. Ojiaku¹, Lucy Izunobi¹

Oyster mushroom Pleurotus tuberregium (Fr.)(Sing), Ǫsu, is a common mushroom which is used as food or medicine, more commonly as a soup thickener. This study investigated the presence of heavy metals (Zn, Pb, Ni, Cu) in wild samples of Pleurotus tuberregium sclerotia consumed within Imo state. The oyster mushrooms purchased from different markets from Imo State were mineralized with H₂SO₄ and HNO₃ and analyzed using flame Atomic Absorption Spectrophotometer (AAS) Thermo Scientific model. The mean concentrations of Pb: 0.13 mg/kg (ranged 0.04±0.005mg/kg to 0.35±0.005mg/kg), Zn: 1.26mg/kg (ranged from 0.03 ± 0.007 mg/kg to 3.25 ± 0.01 mg/kg) and Ni and Cu were 0.0001mg/kg, 0.164mg/kg, respectively. These results were compared with the data from literature and levels set by regulatory authorities, with the conclusion that the consumption of oyster mushroom sclerotium does not pose a toxicological risk. The Zn, Pb, Ni and Cu content of the studied products would contribute to only about 7.4%, 30.3%, 0.001% and 1.91%, respectively of the provisional tolerable weekly intake of Zn, Pb, Ni and Cu. The Cu and Zn contents would contribute to nutritional intake of the metal in the general population. It is recommended that the outer layers of the sclerotia be properly scrapped and washed before use to reduce air-borne metal contamination.

oyster mushroom, trace metal, contamination, target hazard quotient, consumption