Concentration of selected heavy metals in the hair, kidneys and livers of cattle and goats raised on in the oil and non – oil producing areas of Delta State

Abstract

This study evaluated the levels of selected heavy metals namely: lead cadmium, mercury and chromium in the hair, kidneys and livers of cattle and goats reared on oil producing and non oil producing areas of Delta state, Nigeria. Samples of hair, kidneys and livers were collected from four purposively selected local government areas in four replicates, oven dried and digested with 20 mL of a 1:3 mixture of concentrated perchloric acid (HClO₄) and trioxonitrate (v) acid (HNO₃). A completely randomized design was used for the the study. Results showed that mean concentration (mg/kg) of lead in the hair (0.049) of cattle from the oil producing areas varied significantly from those of kidney (0.033) and liver (0.021). While mean lead concentration values showed non - significant variations in the organs obtained from cattle and goats in non oil-producing areas. Cadmium values (mg/kg) ranged from 0.010 to 0.045 in cattle and from 0.000 to 0.029 in goats with significant variations between the organs. Mean values of mercury concentration (mg/kg) in cattle were between 0.053 to 0.078 and 0.052 to 0.056 in goats from theoil producing areas. Mercury concentration in the organs of cattle in the non- oil producing areas varied significantly. Chromium concentration (mg/kg) of organs in cattle from the oil producing areas varied from 0.019 to 0.024 and 0.010 to 0.030 in the non -oil producing areas. Mean concentration in the hair, kidney and liver (0.010 - 0.046 mg/kg) of goats in both the oil producing areas and non - oil producing areas did not vary significantly. Also, in cattle, the effect of oil exploration was significant in the concentration of cadmium (0.016 vs 0.043) and chromium (0.016 vs 0.022) in the kidney as well as cadmium (0.010 vs 0.045), Hg (0.031 vs 0.053) and chromium (0.010 vs 0.019) in the liver. In goats, it was significant in the concentration of cadmium in the hair (0.000 vs 0.056) likewise mercury in the kidney (0.031 vs 0.055) of cattle as well as in the hair and liver of goats. Generally, the heavy metals were below or within the tolerable limits set by some regulatory bodies.

Keywords: Heavy metals, hair, organs, maximum tolerant.