An Assessment to Determine the Level of Some Selected Heavy Metals in Rice (Oryza Sativa) Consumed Within Funtua Metropolis

Abstract

The concentrations of heavy metals namely; chromium, cadmium, lead and nickel (Cr, Cd, Pb and Ni) were determined from twelve samples of rice(ORYZA SATIVA) , the samples comprises of six foreign samples and six local samples collected from different markets within Funtua Local Government Area in 2019. The samples were digested in aqua region and the level of heavy metals were determined using Atomic Absorption Spectrophotometer AA500FS Model. Concentrations of the heavy metals in the rice samples were in the order Cr > Pb > Ni > Cd. The highest concentration of cadmium was detected in LR1(0.620mg/kg) and LR5(0.626mg/kg) while the lowest was detected in FR5(0.058mg/kg). The lowest concentration of nickel was detected in in FR6(0.060mg/kg) and LR2(0.090mg/kg) while the highest was detected in LR3(0.910mg/kg) and LR4(0.750mg/kg). The highest concentration of lead was detected in FR6(0.650mg/kg) and LR1(0.580mg/kg) while the lowest was detected in LR2(0.199mg/kg) and LR5(0.212mg/kg). The highest concentration of chromium was detected in LR1(0.840mg/kg), LR4(0.840mg/kg) and FR5(0.760mg/kg) while the lowest was detected in LR6(0.050mg/kg) and FR2(0.080mg/kg). The analysis shows that chromium, nickel, and lead concentrations that accumulated almost all the rice samples exceeded the maximum permissible limits prescribed by the World Health Organization guideline as well as the Food And Agricultural Organization standard. Cadmium concentrations were found in almost all the samples to conform with the standards. The higher levels of heavy metals accumulated by the samples may be attributed to the increase in agricultural activities such as the application of phosphate fertilizer, sewage sludge disposal and other anthropogenic activities which deserve further investigations.