Heavy Metal Contamination of Some Staple Foods across the Agro-ecological Zones of Nigeria

Abstract

Heavy metals determination in staple food commodity is of vital interest because of their toxic nature and relevance to food safety. In this study, the levels of heavy metals (Cd, Pb Fe, and Zn) in some staple foods collected across the seven (7) agro-ecological zones (AEZ) of Nigeria were investigated using the atomic absorption spectroscopic technique (AAS). The mean concentrations of Cd, Zn, Fe and Pb (mg/Kg) were 0.00 – 9.73, 0.07 – 46.72, 0.00 – 0.05 and 0.00 – 87.50 in garri and cereals samples collected across the agro-ecological zones of Nigeria. These values except for Pb in garri samples obtained from humid forest, were found to be below the joint WHO/FAO (2001) safe limit of 0.2 mg/Kg for Cd and Pb respectively in garri and cereals also, the values obtained in all the samples for Fe and Zn as micro nutrients of great importance in human nutrition were found to be below the recommended daily allowance of 425.5 and 99.4 mg/Kg for Fe and Zn in the samples. Data were analysed using ANOVA at p<0.05. Analysis of the variation in levels of heavy metals across the agro-ecological zones showed that their concentrations differed significantly across the AEZ at 95 % confidence. From the results, samples collected from HF had the highest levels of heavy metals analysed and this could be due on environmental factors and crop handling.