Health risk assessment of heavy metals in soil, irrigation water and vegetables grown around Kubanni River, Nigeria

Abstract

The paper analyses the health risk assessment of cadmium (Cd), lead (Pb), zinc (Zn) and mercury (Hg) in irrigation water, soil and two vegetables samples of three different farmlands grown along Kubanni River, Zaria, Nigeria. The concentrations of the heavy metals were determined using atomic absorption spectrophotometry (AAS). The analysis showed that the average concentration of Pb, Cd, Zn and Hg in the vegetable samples, irrigation water and soil of the three farmlands were 8.35, 1.76, 34.80 and 3.93 mg kg-1; 0.46, 0.09, 0.1 and 0.04 mg kg-1; and 7.22, 0.46, 16.46 and 2.03 mg kg-1 respectively. Generally, the transfer factors for the vegetables are in the order of Cd > Zn > Hg > Pb. The associated health risk assessment of the heavy metals to consumers shows that Pb, Zn and Hg in the vegetables were above the FAO/WHO permissible limits. The health risk values of daily intake of metal (DIM) and health risk index (HRI) indicates that Pb, Cd and Hg contamination in the vegetables had the higher capability to pose severe health risk to consumers.