Comparative assessment of heavy metal levels in Animal hide singed with motor vehicle scrap tyres and liquefied petroleum gas (LPG) as source of fuel

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The present study was undertaken to assess the presence and levels of heavy metal contamination (Mg, Mn, Cu, Ni, Zn, Cd and Pb) in goat and sheep hides singed with vehicle scrap tyres or Liquefied Petroleum Gas (LPG) as fuel, using atomic absorption spectrometry. For assessment of contamination, thirty six goat and sheep hide samples from three slaughter points recognized by the Accra Metropolitan Assembly were analyzed. Goat and Sheep hides singed with LPG resulted in some increases in Mg, Zn and Ni, as well as decreases in Mn and Cu levels, however, singeing with vehicle scrap tyres, resulted in elevated concentrations in heavy metals analyzed in both goat and sheep hides. In goat hides, the highest levels of increases by 128%, 26.3%, 105.66%, 37.73% and 14.17% in Mn, Mg, Cu, Zn and Ni from 6.45±0.55mg/kg, 528.35±62.95mg/kg, 5.3±0.8mg/kg, 226.9±56.9mg/kg and 12±1.8mg/kg respectively, to 14.75±2.45mg/kg, 667.35±56.35mg/kg, 10.9±2.7mg/kg, 312.5±22.5mg/kg, and 13.7±1.5mg/kg, respectively were observed when singed with vehicle scrap tyres as fuel. In sheep hides, the highest levels of increases by 57%, 43.53%, 142.25%, 135.21% and 50.42% respectively, in Mn, Mg, Cu, Zn and Ni from 3.55±1.05mg/kg, 482.85±57.35mg/kg, 3.55±0.95mg/kg, and 126.8±43mg/kg and 11.8±0.9 mg/kg to 5.6±1.9mg/kg, 693.05±45.85mg/kg, 8.6±3.1mg/kg, 298.25±26.75mg/kg and 17.75±4.75mg/kg respectively were observed when singed with vehicle scrap tyres as fuel source. Pb and Cd were not detected in any of the samples but Zn levels in all fresh unsinged goat and sheep hides analyzed were already above the Maximum Permissible Limit of 50.0 mg/kg set by the European Commission Regulation and the United States Department of Agriculture. This could be attributed to the prevailing animal rearing and environmental conditions such as soil, pasture, water sources and medication. It was concluded that vehicle scrap tyre singed hides were potentially unsafe for human consumption even though questionnaire survey of butchers revealed that hides singed this way were sold in most major markets in the Accra Metropolis and consumers were not able to tell whether they were buying meat that had been singed with LPG or vehicle scrap tyres as fuel.
A thesis submitted to the Department of Theoretical and Applied Biology, College of Science, Kwame Nkrumah University of Science & Technology, Kumasi in partial fulfilment of the requirements for the award of the Master of Science degree (Environmental Science)