Heavy metal content of selected readily available commercial medicinal plants in Jos Plateau and their potential human health risk

Abstract

This study determined the level of heavy metal contamination in selected medicinal plants sold in Jos Metropolis and assesses the health risks associated with their consumption. Five commonly used medicinal plants (Annona senegalensis, Mangifera indica, Psidium guajava, Vernonia amygdalina, and Vitex donniana) were analyzed for the presence of arsenic (As), cadmium (Cd), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) respectively using inductively coupled plasma mass spectrometry (ICP-MS). The result showed that the concentrations of As, Cd, Hg, Mn, and Zn in all the plants and Pb levels in two plants, V. amygdalina and V. donniana were significantly higher than the WHO recommended limits, indicating a potential health hazard. The calculated values of the hazard quotient (HQ), hazard index (HI), and cancer risk (CR) for the heavy metals exceed the acceptable levels for both adults and children, suggesting a high vulnerability to heavy metal toxicity and carcinogenicity with the highest and lowest HI values obtained by V. amygdalina (47.3) for children and P. guajava (9.63) for adults. The CR associated with Ni and As for adults and children indicated high carcinogenic risk. In contrast, the CR values for Cd and Pb for adults and children indicated a moderate CR. Based on the results and risk assessment provided by this study, the consumption of medicinal plants suggests a high vulnerability to heavy metal toxicity. It can be concluded that the consumption of medicinal plants poses a serious threat to human health due to heavy metal contamination and calls for implementing preventive measures and risk communication among users of these products to safeguard the health of the residents.