Heavy metal accumulation in soil is of concern in agricultural productions due to its adverse effect on food quality and crop growth. This study, therefore, examines the heavy metal concentrations of some commonly consumed foods collected in some parts of southwestern Nigeria. Five food samples (potato, sorghum, maize, yam and cassava) were collected from five different locations and analyzed for metals using standard procedures. Soil samples where the food crops were grown were also collected and analyzed for heavy metal concentrations. Metals analyzed were zinc (Zn), lead (Pb), copper (Cu), cadmium (Cd) and chromium (Cr). Data from metal analyses were subjected to Analysis of Variance (ANOVA), Pearsonâ€™s Correlation Coefficient and Duncan Multiple Range Test (DMRT). Results showed that heavy metal levels were significantly (p<0.05) different in sorghum, maize and yam. Maize recorded the highest metal concentrations for Zn (5.91ï‚±3.08 Âµg/g), Pb (2.87ï‚±1.33 Âµg/g), Cu (2.12ï‚±0.94 Âµg/g), Cd (0.03ï‚±0.05 Âµg/g) and Cr (4.53ï‚±2.58 Âµg/g); followed by sorghum: Zn (4.35ï‚±1.94 Âµg/g), Pb (2.51ï‚±1.49 Âµg/g), Cu (1.81ï‚±0.97 Âµg/g), Cd (0.02ï‚±0.04 Âµg/g) and Cr (2.88ï‚±1.88 Âµg/g), and then in yam: Zn (1.45ï‚±1.03 Âµg/g), Pb (0.90ï‚±0.68 Âµg/g), Cu (1.22ï‚±0.60 Âµg/g), Cd (0.00ï‚±0.00 Âµg/g) and Cr (1.54ï‚±0.44 Âµg/g). There was a positive relationship between the metal concentrations in food items and the soil where they were grown indicating metal bioaccumulation in crops.
Keywords: Heavy metals, dietary products, soil, health.