Safety evaluation of human exposure to potentially toxic metals in the organs of sheep from southern Nigeria

Introduction

The concentrations and risks of metals (Cd, Pb, Cr, Ni, Cu, Co, Mn, Zn and Fe) in organs of sheep from Southern Nigeria were investigated in this study.

Methodology

A total of 105 sheep organs (kidney, liver and muscles) were collected from abattoirs in five widely distributed areas (Asaba, Benin, Onitsha, Sapele and Warri) in southern Nigeria. The organs were digested using a mixture of nitric and perchloric acids and thereafter the metal concentrations in the digested sample solutions were determined using an atomic absorption spectrophotometer.

Results

The mean concentrations of metals (mg kg⁻¹) were as follows: Cd: 0.05–0.37, Pb 0.86 to 1.99, Cr: 2.20–3.03, Ni: 1.87–3.54, Cu: 17.4–24.3, Co: 1.45–4.30, Mn 192–410, Zn: 41.8–117 and Fe: 423–1068. The concentrations of the metals in the organs were in the order of Fe > Mn > Zn > Cu > Ni > Cr > Co > Pb > Cd while the ability of the sheep organs to accumulate the studied metals followed the order of liver > kidney > muscles. The estimated daily intake values suggested that except for Mn, the intake of metals from the ingestion of these sheep organs was below their respective PTDI. The hazard index and total cancer risk values show that there are no possible risks of non-cancer and cancer risks associated with the consumption of the sheep's organs.

Conclusion

Although there are no health risks associated with the metals in the sheep organs from southern Nigeria, there is, however, a need for continuous monitoring of contaminants in sheep and other animal organs.