Assessment of Heavy Metal Contents in Some Common Spices Available in the Local Market of North Shewa Zone, Oromia Regional State, Ethiopia

Abstract

The objective of this study was to determine the heavy metal contents of some common spices commercially available in the North Shewa Zone, Oromia region, Ethiopia. Korarima seeds (Aframomumcorrorima), ginger rhizomes (Zingiberofficinale), red pepper fruit (Capsicum annum), and turmeric rhizomes(Curcuma longa) samples were randomly collected from the Fiche open market. These spices samples were digested using a mixture of 3 mL of HNO3 (69–72%) and 1 mL of HClO4 (70%). The content of heavy metals (Fe, Zn, Cu, Cr, Mn, Ni, Cd, and Pb) in spices was determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The results obtained showed that the concentrations of heavy metals in the korarima, red pepper, ginger and turmeric samples in mg kg− 1 dry weight were in the range of Fe (38.7–98.9), Mn (10.5-257.3), Zn (7.3–29.2), Cu (1.7–6.5), Cr (5.4–9.7), Cd (1.5–2.9), Pb (14.5–28.4) and Ni (3.9–6.7. The heavy metal contents in korarima, red pepper, ginger, and turmeric samples were compared with the maximum values given by the World Health Organisation (WHO) in the vegetables. Accordingly, Fe, Zn, Cu, Cr, Mn, Ni, and Cd values in the spice samples were found to be lower than the maximum limit of WHO, while the levels of Pb in four spices samples were higher than WHO permissible limit. Moreover, Mn (only in ginger) exceeded the maximum allowable concentrations among spices. This study shows that consumption of korarima, red pepper, ginger, and turmeric may have a serious health threat to consumers due to the high content of lead and manganese in spices. Therefore, it is suggested that further study be conducted on spices samples based on the origin of cultivation to determine which hotspot is responsible for high levels of contamination of lead and manganese to protect consumers.