Assessment of some heavy metals concentration in selected cereals collected from local markets of Ambo City, Ethiopia

摘要

The concentrations of nine heavy metals (Fe, Zn, Cu, Mn, Ni, Co, Cr, Pb and Cd) in four varieties of cereals (wheat, barley, sorghum and maize) purchased from Ambo market, Ethiopia were determined using Atomic Absorption Spectrophotometers (AAS). Dry ashing method was used to destroy the organic matter to determine the content of nine heavy metals. The results showed that the concentrations of heavy metals in mg kg?1 dry weight were in the range of: Cu (0.13 - 1.72), Fe (0.40 - 36.45), Zn (0.66 - 8.54), Mn (0.42 - 7.67), Co (0.14 - 0.45), Ni (ND - 0.43), Cr (0.29 - 0.95) and Pb (non-detectable - 0.08), respectively. Cadmium was not detected in any of the cereal samples. In addition, the mean concentrations of heavy metals in cereals purchased from Ambo market decreases in the following order: Fe > Zn > Mn > Cu > Cr > Co > Ni > Pb > Cd. The trace metals Fe, Zn and Mn were higher than the entire heavy metals in the samples investigated while Cd and Pb were in minor quantities and hence the cereals were free from toxic heavy metals. The author concluded that the levels of heavy metals determined in the analyzed cereal samples were found below the permissible limits set by FAO/ WHO; hence they are safe for human consumption and can be considered as good sources of essential trace metals to the individuals.