Heavy Metal Burden and Evaluation of Human Health Risks in Tomato Fruits Cultivated in Katsina State, North West Nigeria

Abstract

This study was conducted to determine the heavy metals concentration in Tomato fruits cultivated in Katsina State Nigeria. The objectives were mainly to detect the presence of heavy metals in the cultivated Tomato fruits in the study area, compare the concentration of heavy metals in samples in relation to the permissible limits specified by WHO/FAO/USEPA Standards. Samples of cultivated tomato fruits 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 intake of carcinogenic heavy metals was estimated using the Incremental Lifetime Cancer Risk (ILCR). Results from this study has shown that with the exception of the mean values for the heavy metal Pb (1.171–1.21 mg/kg), the mean concentration (mg/kg) range values of Zn (0.558- 1.851), Fe (0.880–1.181), Mn (0.458-0.671) and Cd (0.054-0.062) were below the WHO/FAO maximum permissive limits. The results have indicated that the estimated daily intake (EDI) of the heavy metals were lower than the tolerable daily intake limit set by the USEPA in all the samples. All the studied tomato fruits showed the risk level (HI < 1). 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 were in the decreasing order Mn>Zn>Pb>Fe>Cd, for all the tomato fruits respectively. ILCR for Cd violated the threshold risk limit (>10−4) and ILCR for Pb reached the moderate risk limit (>10−3) in all the studied samples in adults, While in children ILCR for both Pb and Cd violated the risk. The sampling area trend of risk for developing cancer as a result of consuming the studied samples showed in decreasing order: Daura senatorial zone > Funtua senatorial zone> Katsina senatorial zone for both adult and children.  Cumulative cancer risk (∑ILCR) of all the studied tomato fruits reached the moderate risk limit (>10−3) in adults, while in children it is above the moderate risk limit (>10−2). The study suggests that consumption of the studied tomato fruits in Katsina state is of public health concern as they may contribute to the population cancer burden.