Human health risks due to heavy metals through consumption of wild mushrooms from Macheke forest, Rail Block forest and Muganyi communal lands in Zimbabwe

Abstract

The levels and sources of toxic heavy metals in Amanita loosii (AL) and Cantharellus floridulus (CF) mushrooms and their substrates were studied in some parts of Zimbabwe, Rail Block forest (mining town), Macheke forest (commercial farming), and Muganyi communal lands. The mushrooms and their associated soils were acid digested prior to Al, Pb, and Zn determination by inductively coupled plasma optical emission spectroscopy. The transfer factors, mushrooms-soil metal correlation coefficients, daily intake rates, weekly intake rates, and target hazard quotients were calculated for each metal. The concentration of Zn, Al and Pb in mushrooms ranged from 1.045 ± 0.028 to 7.568 ± 0.322, 0.025 ± 0.001 to 0.654 ± 0.005, and a maximum of 5.78 ± 0.31 mg/kg, respectively, in all the three sampling areas. The mean heavy metal concentrations among the three sampling areas decreased as follows: Rail Block forest (mining town) > Macheke forest (commercial farming) > Muganyi communal lands for the concentrations in both mushrooms and total concentration in their substrates. C. floridulus accumulated higher concentrations of Al, Zn, and Pb than A. loosii at each site under study. Zn in both AL and CF (Muganyi communal lands) and Pb in AL (Rail Block forest) were absorbed only from the soils, while other sources of contamination were involved elsewhere. The consumption of 300 g of fresh A. loosii and C. floridulus per day by children less than 16 kg harvested from Rail Block forest would cause health problems, while mushrooms from Macheke Forest and Muganyi communal lands were found to be safe for human consumption. Due to non-biodegradability and bioaccumulation abilities of heavy metals, people are discouraged to consume A. loosii and C. floridulus from Rail Block forest for they have significant levels of heavy metals compared to those from Macheke forest and Muganyi communal lands.