Assessment of Heavy Metal Contamination in Combretum micranthum Leaves and Decoctions: Implications for Human Health

Abstract

Combretum micranthum is a well-known medicinal plant in Africa and the decoction of its leaves is used as a drink or to treat various diseases such as malaria, high blood pressure and liver disorders, among others. Due to its high consumption by all sections of the Senegalese population, we felt that its heavy metal intake should be examined to see its impact on health. Leaves of two species of Combretum micranthum produced in the central (I) and southern (II) regions of Senegal and their decoctions in ultrapure water (Ii) and (IIi) were analyzed for 12 elements (Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Ag, Cd, Pb, Bi) by inductively coupled plasma optical emission spectrometer (ICP-OES). The concentrations of heavy metals (μg/g) are in the ranges 2.55 – 84.19 for Cr, 5.21 – 379.72 for Mn, 0.00 – 317.80 for Fe, 0.08 – 1.08 for Co, 1.54 – 8.88 for Ni, 1.75 – 8.08 for Cu, 0.91 – 9.70 for Zn, 0.00 – 0.16 for Cd, 0.46 – 0.84 for Pb. As, Ag and Bi are below detectable limits in any of the samples by ICP-OES analysis. Among all samples, manganese content was highest and represented 46.85% for I , 64.18% for II , 86.88% for Ii and 46.27% for IIi , of the total heavy metal concentrations. The results showed that the leaves of both varieties of Combretum micranthum and decoctions made from these leaves contain heavy metal levels lower than the values recommended by the WHO for consumed medicinal plants. Overall, Variety I harvested from peri-urban areas contains more metals than Variety II harvested from forest.