Regardless of contamination level, higher proportion of the people living in rural areas relied on nature for foods and sources of medicines for treatments of various ailments. The study evaluated the phytochemical contents, heavy metals concentration and potential human health risk in the leaves and bark of the medicinal plants around quarry site of Kiru, Kano state Nigeria. A composite sampling method was used for the collection of four medicinal plants namely Neem (Azadirachta indica), Baobab (Adonsonia digitata), African birch (Anogeissus leiocarpus) and Mango (Mangifera indica) for ethanolic phytochemical screening. The samples were digested and analyzed for heavy metals using AAS. The results of phytochemical analysis revealed the presence of alkaloid, flavonoid, saponin and phenol with proportion of 8.85-26.98%, 13.82-37.86%, 4.07-28.73% and 5.34-25.01% respectively. The results of the heavy metals analysis ranged from BDL-0.78 mgkg-1 for Cd, 7.8-36.30 mgkg-1 for Cr, 0.04-8.16 mgkg-1 for Cu, BDL-34.02 mgkg-1 for Pb and 1.96-33.63 mgkg-1 for Zn respectively. Metals concentrations obtained from the study site were significantly higher than the control samples and were all within the permissible limits set by WHO for medicinal Plants except for Pb, Cd and Cr respectively. The result further revealed that the calculated values for non-carcinogenic risk were greater than 1 indicating a significant health risk to consumers whereas the carcinogenic risk were within the acceptable limit except in Mangifera indica bark. The medicinal plants under study were significantly contaminated with heavy metal which has resulted to increase in the synthesis of secondary metabolites to ensure the adaptation and survival of these plants under stress. Consumption of these plants for medicinal and other uses can pose a significant health problems. There is a need for mitigation procedure in the area to safeguard the human health and environmental quality.
Suleiman et al. (Tue,) studied this question.