Risk assessment of heavy metal content in yam tubers locally produced in selected local government areas of Taraba State, Nigeria

Abstract

Abstract. Olawale OF, Abah MA, Emmanuel OP, Otitoju GT, Abershi AL, Temitope DF, Andrew AE, Abdulkadir S, John A. 2023. Risk assessment of heavy metal content in yam tubers locally produced in selected local government areas of Taraba State, Nigeria. Asian J Nat Prod Biochem 21: 6-12. Yam is one of the most cultivated tubers in northern Nigeria. The increasing yam consumption and pest attack on the crop have led to increased use of fertilizers and pesticides during the cultivation process to prevent and control pest attacks. This study aims to determine the concentration of several heavy metals (Hg, Cr, Cd, Pb, and As) in locally produced yam samples harvested from Jalingo, Takum, Mutum Biyu, Wukari and Zing Local Government Area (LGA) of Taraba state as well assessing the Total Cancer Risk and Hazard Quotient associated with consuming the analyzed yam samples. The samples were collected in duplicates from five LGAs of Taraba state (Jalingo, Takum, Mutum Biyu, Wukari, and Zing). They were washed, peeled, and dried before being analyzed for heavy metal content using the method of Nitric acid-hydrochloric acid digestion (APHA 3030 f. 2018) by Atomic Absorption Spectroscopy (AAS). The data were analyzed using ANOVA (P<0.05). The results showed that Hg and As values were below the permissible limit recommended by WHO, with values ranging from 0.02-0.05 mg/kg. Cadmium content was significantly high, ranging from 8.00-14.00 mg/kg. Chromium content from Zing LGA was higher than in other locations, ranging from 100.00 to 103.00 mg/kg. The risk assessment analysis revealed that chromium and arsenic had the highest and lowest hazard quotient values of 37.32 and 0.00180, respectively, for yam samples cultivated in Jalingo LGA. The highest TCR value was obtained in chromium (3.2×10-3) and the lowest in the lead (1.23×10-8). High levels of heavy metals present in yam samples could be due to excessive use of pesticides or fertilizers during cultivation, burning of plastics and rubbers, deposition from mountains, and other anthropogenic activities. The results of this study are expected to gain public awareness that consuming locally produced yam from LGAs contaminated with heavy metals is at risk of heavy metal toxicity, such as renal, neural, and respiratory disorders, among others.