Health Risk Assessment for Carcinogenic and Non Carcinogenic Heavy Metal Exposure from Hibiscus Leaf Cultivated in Katsina State, North West Nigeria

Abstract

This study was conducted to determine the heavy metals concentration in Hibiscus leaves cultivated in Katsina State Nigeria. The objectives were mainly to detect the presence of heavy metals in the cultivated Hibiscus leaves 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 Hibiscus leaves were collected in the year 2017 from the selected area.  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 for the adult and children population through intake of carcinogenic heavy metals in the samples was estimated using the Incremental Lifetime Cancer Risk (ILCR). Results from this study shows that with the exception of Pb with mean concentration of (0.508-0.978), the mean concentration (mg/kg) range values of Cr (0.135-0.261), Cd (0.042-0.051), Fe (0.684-0.978) and Zn (1.048-1.208) in the samples were generally lower than the USEPA, 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 both samples and the health risk index (HRI) for all the heavy metals were <1. The target hazard quotient (THQ) for the samples for both the adult and children population was in the decreasing order of Zn>Pb>Fe>Cr>Cd. ILCR for Cd is below the threshold risk limit (>10−5) 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 in samples from Dabai, Daura, Funtua, Matazu and Zango for all samples have reached the moderate risk limit (>10−3), while the ILCR for Pb in samples from Birchi, Dutsinma, Kafur, Katsina and Malunfashi were beyond the moderate risk level (>10−2). The sampling area trend of risk for developing cancer as a result of consuming the studied samples showed: Funtua > Daura > Dutsinma > Katsina > Malunfashi > Matazu > Zango > Ingawa > Kafur > Dabai > Birchi for both adult and children, cumulative cancer risk (∑ILCR) of all the studied Hibiscus samples have reached the moderate risk limit (>10−3) in adult. While in children with the exception of the sample from Birchi, Dabai and Kafur which are within the moderate cancer risk (>10−3) limit, all other samples were beyond the moderate cancer risk (>10−2) limit. The study suggests that consumption of the studied samples in Katsina state is of public health concern as they may contribute to the population cancer burden.