Evaluation of Health Effect of Some Selected Heavy Metals in Maize Cultivated in Katsina State, North West Nigeria
Authors: Yaradua A. I. , Alhassan A. J. , Saulawa L. A. , Nasir A. , Matazu K. I. , Usman A. , Idi A. , Muhammad I. U. , Mohammad A. 
Published: June 2019

This study was conducted to determine the heavy metals concentration in maize cultivated in Katsina state Nigeria. The objectives were mainly to detect the presence of heavy metals in the cultivated maize in the study area, compare the concentration of heavy metals in samples in relation to the permissible limits specified by WHO/FAO/USEPA Standards and asses the health risks to the local consumers. Samples of cultivated maize were collected in the year 2017 from the selected areas.  Analysis for the concentration of these heavy metals; Cr, Cd, Fe, Ni, Mn, Pb and Zn was conducted by the use of AAS (by Atomic Absorption Spectrophotometry) method. The health risks to the local inhabitants from the consumption of the samples were evaluated based on the Target Hazard Quotient (THQ). The possibility of cancer risks in the samples through the intake of carcinogenic heavy metals was estimated using the Incremental Lifetime Cancer Risk (ILCR).  Results from this study have shown that with the exception of the heavy metal Pb the concentration values of Cr, Cd, Fe, Mn and Zn in the samples were generally lower than the USEPA, WHO/FAO maximum permissive limits. The results have also indicated that the estimated daily intake of the heavy metals was lower than the tolerable daily intake limit set by the USEPA in all samples. The risk level of Target Hazard Quotient (THQ < 1) was observed for all the evaluated heavy metals for both adults and children.. The THQ for the samples was in the decreasing order Zn>Pb>Fe>Cr>Cd, for all the samples respectively. All the studied samples showed the hazard index (HI < 1) with highest in the sample from Dabai and lowest in the sample from Funtua. In adults the ILCR for Cd violated the threshold risk limit (>10−4) in all the studied samples, while the ILCR for Pb reached the moderate risk limit (>10−3) except for the sample from Kafur which is above the limit (>10−2). In children ILCR for Cd in all samples and Pb for samples from Birchi, Katsina and Malunfashi has reached the moderate risk limit (>10−3) while the ILCR for Pb in samples from Dabai, Funtua and Kafur is above the limit (>10−2). The trend of risk for developing cancer as a result of consuming the studied maize samples showed: Kafur> Dabai > Funtua> Malunfashi > Katsina. Cumulative cancer risk (∑ILCR) in adults of all the studied maize samples reached the moderate risk limit (>10−3) except for sample from Kafur which is above the moderate risk limit (>10−2). While the cumulative cancer risk (∑ILCR) in children of all the studied maize samples is above the moderate risk limit (>10−2) except for sample from Katsina which is within the moderate risk limit (>10−3). Among all the studied samples maize sample from Kafur has the highest chances of cancer risks (ILCR 1.297980 × 10−2 in adults, 1.510018 × 10−2 in children) and sample from Katsina has the lowest chances of cancer risk (ILCR 1.68603093 × 10−3 in adults, 7.775840 × 10−3 in children). The study suggests that consumption of the studied maize samples in Katsina state is of public health concern as they may contribute to the population cancer burden.