Ecological distribution, heavy metals profiling and human health risk assessment of medicinal plants used for tonsillitis and wounds treatment: A chemometric approach

Medicinal plants in Ethiopia are easily accessible, relatively low cost and trusted by the community, which drives people to use them to treat a variety of ailments for many years. For instance, Kalanchoe petition, Rhamnus prinoide & Acmella caulirhiza are the most popular medicinal plants that have been used for treating tonsillitis, while Brucea antidysenteric, Justicia shimperian, Jatropha curcas & Prunus Africana have been used for treating wounds. However, the presence of toxic chemicals like heavy metals above threshold concentrations poses a global threat to human health. This study was conducted to determine the levels of heavy metals and to evaluate non-carcinogenic and carcinogenic health impacts posed by using medicinal plants so as to create awareness among users about the chemical compositions of these plants. Five hundred grams of leaves, barks and flowers of the medicinal plants were collected randomly from ten plants from Ayehu Guwagusa and Asagirt districts, Amhara Regional State, Ethiopia in July 2022, and 0.5 g of homogenized samples were digested with HNO3 and HClO4 and the levels of metals were determined using Flame Atomic Absorption Spectroscopy (FAAS). The levels were (mg/kg) Fe: 173.6 ± 9.1-332.2 ± 9.2, Zn: 8.7 ± 0.2-40.2 ± 0.3, Cu: 29 ± 4- 84.1 ± 4.7, Mn: 17.03 ± 1.6- 77.4 ± 1.7, Ni: BDL- 41.4 ± 4.3, and Pb: 21.3 ± 15.1- 49.9 ± 9.6. Cd was found to below the detection limit. The hazard index is less than unity, ranged from 6.64 × 10−4 (J. schimperiana) to 6.43 × 10−3 (J. curcas) for all samples, indicating no significant non-carcinogenic effect on users due to heavy metals. Similarly, the carcinogenic risk values of Ni were raged from 6.64 × 10−9 in B. antidysenterica to 1.16 × 10−8 in J. curcas and for Pb it was found to be 6.04 × 10−8 in R. prinoides and 1.41 × 10−7 in J. curcas. Therefore, the results of this study indicated that the exposed populations are unlikely to experience any adverse cancer risk.