TOXIC METAL RESIDUES IN NON-EDIBLE ANIMAL BYPRODUCTS

Abstract

Environmental pollution by heavy metals is a major problem worldwide. Domesticated animals such as cattle and camel share the same environmental conditions like human and they are exposed to heavy metals via different sources. Therefore, these animals are considered as ideal bio-indicators for human exposure to heavy metals. Heavy metals accumulate in the different tissues of the animals. Estimation of toxic metal residues such as arsenic (As), mercury (Hg), lead (Pb) and cadmium (Cd) in the animal edible tissues had been extensively studied. However, estimation of such toxicants in the non-edible animal byproducts had received little attention. Additionally, non-edible animal byproducts are frequently used in many industries such as animal feed additives and leather fabrication. Therefore, this study was undertaken to estimate the residual concentrations of As, Hg, Pb and Cd in the hair, hides and bones of cattle and camel slaughtered at Zagazig, Abo-Hammad and Belbies cities, Sharkia Governorate, Egypt. Metal-metal correlations were additionally calculated. The achieved results indicated exposure of cattle and camel to high levels of heavy metals, particularly lead and arsenic. Camel had higher concentrations (mg/kg ww) of arsenic compared with cattle particularly in hair (38.57 ± 8.77 and 22.48 ± 1.91 in camel and cattle, respectively). Bone had the highest load of the measured metals among examined samples. For instances, in camel, elemental concentrations (mg/kg ww) in bone were 34.53 ± 6.16 (As), 3.41 ± 0.56 (Hg), 2.76 ± 0.36 (Pb) and 0.11 ± 0.01 (Cd). Samples collected from Zagazig city were highly contaminated compared with other locations. Significant positive correlations were observed between lead - mercury, lead - cadmium and arsenic- mercury (r <0.0001 in each). Contaminated non-edible animal byproducts should be hygienically disposed and avoid its introduction to downstream industries. It is highly recommended to control environmental pollution with heavy metals in Egypt.