Variation of heavy metal contamination between mushroom species in the Copperbelt province, Zambia: are the people at risk?

Abstract

Heavy metal contamination in mushrooms and the associated health risk are unknown in Zambia. We studied seven heavy metals and 23 mushroom species and interviewed 400 people. Mushrooms were found to contain substantial concentrations of Cu (894.4 ± 267.9 µg g-1 ) and Fe (998.4 ± 454.0µgg-1 ). Significant differences in transfer factors of metals occurred between mushroom species (F11,66 = 5.36, P< 0.001). The most efficient were L. kabansus (for Zn and Ni), A. miomboensis (for Cu and Fe) and T. clypeatus (for Mn, Pb and Co). These species were also among the most preferred mushrooms for consumption based on the interviews conducted. Although 60% of the mushrooms observed were edible, only 20% were frequently consumed during the mushroom season. High positive correlations observed between soils and mushrooms suggest that contamination in mushrooms increases with soil pollution. The estimated daily intake of metals and the target hazard quotient through mushroom consumption were found to be significantly influenced by mushroom species (F11,66 = 38.8, P< 0.001) suggesting that the level of exposure to heavy metals depends on the species of mushroom consumed. The study has revealed that heavy metal concentrations in mushrooms exceed permissible limits and vary between species. Transfer efficiency also varies between mushroom species and contamination in mushrooms increases with soil pollution. The fact that concentrations of metals in soil were significantly high, the risk of exposure through mushroom consumption and possibly soil ingestion is even higher. © 2019 Society of Chemical Industry.