Determination of the Level of Heavy Metals in the Selected Cereals from Debre Markos Local Market, Amhara Region, Ethiopia

Abstract

Environmental contamination by heavy metals has become a worldwide problem in recent years because of industrial and agricultural development which causes cereal crop contamination via their wastes. The presence of toxic heavy metals in cereal crops accumulate in the body for a prolonged period of time which poses acute and chronic health risks. The aim of the study was to assess the level of heavy metals in selected cereals sold at Debre Markos local market, in Ethiopia. The samples were prepared for analysis by using the dry ashing method, and their cadmium, lead, chromium, and copper contents were analyzed by using microwave-induced plasma-atomic emission spectroscopy (MP-AES) and were expressed in mgkg-1 dry weight. The accuracy of the method was analyzed by the spike recovery test. The percentage recovery for Cr, Cu, Pb, and Cd in each sample ranged from 85.6 to 112.8%. The levels of heavy metals (mean ± SD) were as follows: chromium, 2.20 ± 0.072, 2.22 ± 0.061, 1.57 ± 0.48, and 1.84 ± 0.26; copper, 2.94 ± 0.19, 2.31 ± 0.06, 1.28 ± 0.13, 1.52 ± 0.035, and 2.31 ± 0.06; lead, 0.49 ± 0.031, 0.34 ± 0.121, 0.52 ± 0.029, and 0.37 ± 0.15; and cadmium, 2.01 ± 1.73, 1.84 ± 1.60, 1.95 ± 1.69, and 1.93 ± 1.67 for barley, teff, wheat, and maize, respectively. This study revealed that the levels of Cr and Cu are generally below the permissible limit. However, the levels of Pb and Cd in all cereal samples were found to be above the permissible limit set by FAO/WHO, 0.2 and 0.1 mg kg-1, respectively. The findings of the study suggest that most of the analyzed crops contained unsafe levels of lead and cadmium that exceeded the WHO permissible limits. Therefore, regular monitoring of these toxic metals in cereal crops should be carried out to prevent heavy metal toxicity associated with the consumption of some cereal crops marketed in the Debre Markos local market, Ethiopia.