Heavy Metals and Carcinogenic Risk Assessment in Free-Ranged Livestock of LeadContaminated Goldmine Communities of Zamfara State, Northern Nigeria

Abstract

The consumption of meat is of great importance as it provides a good source of proteins and a significant amount of essential trace  elements to the body. However, contamination of meat and meat products with heavy metals is becoming a serious threat to food safety  and public health. Therefore, the present study aimed to evaluate the concentration of some heavy metals in the muscles and entrails of  free-ranged cattle, sheep, and goats. A total of sixty (60) fresh samples of muscles, liver, kidney, small intestines, and stomach of free  ranged cattle, sheep, and goats were collected from abattoirs of different goldmine communities of Anka, Bukkuyum, Maru, and Talata- Mafara Local Government Areas of Zamfara State, Nigeria. The samples were digested using 10 mL of a mixed 70% high-grade  concentration of HNO3 and 65% HCl (4:1 v/v); the mixture was heated until dense fumes disappeared forming a clear transparent  solution and diluted to 50 mL with deionized water. Actual concentrations of Cd, Cr, Cu, Co, As, Ni, Mn, Pb, and Zn were determined using  a Microwave Plasma Atomic Emission Spectrophotometer (MP-AES). Results indicate goat liver had the highest mean concentration of  lead, arsenic, cobalt, and manganese (12.43± 0.31, 14.25±0.32, 3.47± 0.86, and 12.68± 0.92 mg/kg respectively), and the kidney had the highest concentration of copper and zinc (10.08±0.61 and 24.16±1.30 mg/kg respectively). Sheep kidneys had the highest bioaccumulation of cadmium and nickel (7.75± 0.65 and 2.08±0.10 mg/kg respectively) while chromium was observed to accumulate  mostly in cattle muscles when compared with all other organs analysed. The target hazard quotients (THQs) for all the metals analyzed  were below 1.0, but the risk indices for carcinogenicity (TR) predictably suggest exposed individuals were most likely to develop the  disease. Therefore, intensive public health awareness of the risks associated with the consumption of heavy metal-contaminated meat  should be prioritized.