Levels of selected toxic heavy metals in the root of Rumex abyssinicus, a traditional medicinal plant, collected from two locations in the city of Addis Ababa

Abstract

In this study, the contents of selected heavy metals; Fe, Cu, Zn, Cd, Cr, Pb and Ni in the root of Rumex abyssinicus (RA) were determined by flame atomic absorption spectroscopy (FAAS) after acid digestion. The digestion required 3:1 HNO₃/HCl (v/v) for 3 h, with temperature of 300°C for complete digestion of 0.5 g RA roots using Kjeldahl apparatus. The levels of metals; Fe, Zn, Cu and Ni were 31.9, 7.76 and 4.73 mg kg^-1, respectively, for the samples collected from Addis Ababa University, AAU, Science campus (RA-A samples), and 5.59 Zn, 103 Fe and 3.01 Ni, all in mg kg^-1, were found in RA-W sample from Weregenu/Gerji area in AA. Validity of the optimized procedure was evaluated using spiked sample whose recovery varied from 89.8-95.1%. The findings confirmed that only Fe was higher than the tolerance limits. From the health risk perspective, the hazard quotient (HQ) value of Fe for both RA-A and RA-W samples exceeded 1, indicating potential health risks. The hazard index (HI) value suggested that consumption of the root of RA-A and RA-W samples could pose potential health risks over long-term consumption. This may signify the non-carcinogenic health risk associated with consuming RA plant, though continuous regulatory control may necessitate to ensure safety to the consumers.

KEYWORDS: Medicinal plant, Wet digestion, Rumex abyssinicus, Trace metals, Health risk assessment, Pearson correlation.

Bull. Chem. Soc. Ethiop. 2025, 39(2), 243-256.                                                              

DOI: https://dx.doi.org/10.4314/bcse.v39i2.5