ASSESSMENT OF SELECTED HEAVY METALS IN PARTS OF SLAUGHTERED CATTLE AND GOATS CENTRAL ABATTOIR FROM AKINYELE, IBADAN

Abstract

Meat and offal obtained from cattle and goats sold in open markets serve as sources of protein, but may be susceptible to heavy metal contamination due to illicit disposal and emission in the environment. Consumers’ knowledge on the possible exposure to heavy metal contamination in meat and its associated health risks is low. Therefore, this study aimed at assessing heavy metal levels in these products.

A cross-sectional study design with observational and laboratory analysis components was adopted. Lead, cadmium and chromium residues in blood, muscle, liver and kidney of cattle and goats slaughtered in central abattoir, Akinyele, Ibadan were determined. The abattoir was selected because it is the largest abattoir supplying live animals and meat to residents of Ibadan. A total of 40 animals (20 each of white Fulani cattle and red Sokoto goats) were purposively selected over a period of 8 weeks in conformity with FAO quality control guidelines. Values were compared with Joint FAO/WHO guidelines. These animals were of different sexes and ages (determined by the use of their dentition). Samples of blood was collected from jugular vein at slaughter using 5ml syringe and 21 gauge needle, external abdominus muscles, liver apical lobes and kidney cortices were collected. Samples were analysed using Atomic Absorption Spectrophotometer (AAS) for lead, chromium and cadmium. Statistical analysis was done using descriptive statistics and t-test at 5% level of significance.

Age of 14 male and 6 female cattle was 49.5±14.7 months while the age of 12 male and 8 female goats was 28.8±8 months. Cadmium was found in 115 samples (71.9%), lead in 26 samples (16.3%) and chromium in 17 samples (10.6%). Chromium value in blood of cattle (0.6±0.0µg/ml) was significantly lower compared to goats’ (2.4±2.6µg/ml). In muscle tissue, liver and kidney, chromium values for cattle and goats were 0.6±0.0, 1.3±0.9 and 2.3±3.0 mg/kg and 0.0, 0.6±0.0 and 0.0mg/kg respectively. Chromium residues were higher in liver and kidney of cattle and goats’ blood than permissible limits of 1mg/kg. Cadmium value in blood of cattle (5.7±2.1 µg/ml) was significantly lower compared to goats’ (6.8±3.0µg/ml). In muscle tissue, liver and kidney of cattle and goats cadmium values were 3.8±2.1, 5.2±2.3 and 5.7±2.3mg/kg and 5.4±1.9, 5.5±2.9 and 4.8±1.9mg/kg respectively. These values were higher than permissible limit of 0.5-1.0mg/kg. Lead residual values in blood of cattle and goats were 0.5±0.6 and 0.0µg/ml, while in muscle, liver and kidney of cattle and goats were 0.1±0.2, 0.0 and 0.0mg/kg and 0.0, 0.0 and 0.0mg/kg respectively. These values were within the permissible limits (0.1-0.5mg/kg). Cattle were found to have higher levels of bioaccumulation for lead, cadmium and chromium residues when compared to those of goats.

From central abattoir, Akinyele, Ibadan, cattle and goat meat contained high levels of cadmium and chromium which could pose health risk to consumers. Therefore, public health awareness on the risk associated with cadmium and chromium ingestion and measures to reduce them in meat and meat products should be advocated.