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

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 ۲۰۱۹. The samples were digested in aqua region and the level of heavy metals were determined using Atomic Absorption Spectrophotometer AA۵۰۰FS 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 LR۱(۰.۶۲۰mg/kg) and LR۵(۰.۶۲۶mg/kg) while the lowest was detected in FR۵(۰.۰۵۸mg/kg). The lowest concentration of nickel was detected in in FR۶(۰.۰۶۰mg/kg) and LR۲(۰.۰۹۰mg/kg) while the highest was detected in LR۳(۰.۹۱۰mg/kg) and LR۴(۰.۷۵۰mg/kg). The highest concentration of lead was detected in FR۶(۰.۶۵۰mg/kg) and LR۱(۰.۵۸۰mg/kg) while the lowest was detected in LR۲(۰.۱۹۹mg/kg) and LR۵(۰.۲۱۲mg/kg). The highest concentration of chromium was detected in LR۱(۰.۸۴۰mg/kg), LR۴(۰.۸۴۰mg/kg) and FR۵(۰.۷۶۰mg/kg) while the lowest was detected in LR۶(۰.۰۵۰mg/kg) and FR۲(۰.۰۸۰mg/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.

Keywords:

heavy metals , Aas , Local Rice , ANOVA , Foreign Rice