Toxic Metals Contamination of Paddy (Oryza Sativa) and Imported Rice Sold in Kaduna and Its Human Health Risk Assessment

Abstract Hg, Cd, Pb, As, Ni, Cu, Zn, Mn, Cr, Co and V were evaluated in paddy (Oryza sativa) and foreign rice collected from thirteen local government areas of Kaduna State, Nigeria. Concentration of Cu was below WHO/FAO and NAFDAC (40.00 mg/kg) regulatory limit. Concentration of Zn was within the WHO/FAO limit, Ni (0.03 mg/kg) was above the WHO/FAO threshold limit in samples Le3, Kc1, Ik2, TO and KG. Pb was detected in all samples except inKa2. Co, Fe, Pb, Cd, Mn and Cr were below WHO/FAO and NAFDAC regulatory limits in all samples. Guidance value was not available for V. Associated health risks of these metals show the daily intake of metals (EDIM)for Cd (0.0000935 mg/kg), Cr (0.001105 to 0.002125 mg/kg), Mn (0.00034 to 0.00765 mg/kg). EDIM of As was below the daily limit Target hazard quotient measured for Ni, Pb, Cd, Cr, Mn and Co in all samples were < 1, except for As. There exists cancer risk at a lower limit of 64 chances in 1000 lifetime exposure and an upper limit of 14 chances in 100 lifetime exposure for any combination of two or more of Ni, Pb, Cd, As and Cr available for consumption. Statistical analysis reveals no significant differences (p < 0.05) in the concentrations of Cu, Cr, Mn, Pb, As and V but revealed significant difference in the concentrations of Zn, Ni, Cd, Fe and Co. Hg was not detected in all samples.