Application of linear discriminant analysis for the evaluation of heavy metals in brown and white rice (Oryza sativa) cultivated in Kano, Nigeria

Abstract

Accumulation of toxic metals in locally harvested crops is of growing concern due to food safety and the associated health risks. This study evaluates the levels of some heavy metals (Pb, Cd, Fe, Cu and Mn) in white and brown rice samples locally cultivated in Kano using Atomic Absorption Spectrophotometry (AAS). Significant variations were observed (p<0.05), and found to be associated with the differences in rice type. Pb concentrations in all the rice samples analyzed were 0.291±0.024 to 0.699±0.152 mg/kg which surpassed the maximum limit set by FAO/WHO while other metals were below the safe limits, and Cd was not detected in all the rice samples analyzed. Linear discriminant analysis (LDA) revealed that white rice was much associated with Pb along canonical 1, while Fe and Mn were much associated with brown rice as confirmed by F-Ratio analysis. The presence of high levels of toxic metals beyond the maximum limits in the rice varieties might have originated from the fertilizer and other environmental sources which could be of health concern after consumption.