Accumulation of Metals in the Liver and Kidneys of Cattle from Agricultural Areas in Lusaka, Zambia

Abstract

ABSTRACT. Intensive agricultural practices are recognized as significant sources of metal pollution in soils and pasture. This study investigated metal contamination in cattle offal from an agricultural area in Zambia, where inorganic fertilizers, agricultural lime, and pesticides are routinely applied. The highest median values (mg/kg, wet weight) of Cu (40.9), Zn (35.2), Cr (1.35) and Ni (0.594) were recorded in the liver, whereas the highest median values of Pb (0.061) and Cd (0.049) were found in kidneys. Maximum levels of Hg, As and Co were under 0.2 mg/kg in both organs. Pb and Cd did not exceed the benchmark values in cattle offal for human consumption and did not pose immediate health risks. Concentrations of Ni and Cr could present a public health concern. Monitoring of metal accumulations in offal of cattle, not only from well-known polluted environments but also agricultural areas, should be done regularly for the health of human consumers. KEY WORDS: cattle, kidney, liver, metal accumulation, Zambia.doi: 10.1292/jvms.12-0142; J. Vet. Med. Sci. 74(10): 1345-1347, 2012 The accumulation of toxic metals in food animals is recognized as a public health hazard worldwide. Toxic metals can be lethal and tend to accumulate in the liver, kidneys, bones, and other tissues [8]. Metals including Pb, Cd, Hg, and As are readily transferred through food chains and pose potential health risks to human consumers. Sources of metal contamination in livestock production systems can be natural and anthropogenic. In agricultural systems that integrate livestock and crop production, intensive agricultural practices are recognized as significant sources of metal accumulation [9]. Fertilizers and agricultural lime contain metal impurities, and it is widely reported that application of these agrochemicals, especially phosphate fertilizers, results in accumulation of metals in agricultural soils [9,12]. Metallo-pesticides, including insecticides, fungicides, and herbicides, are also known to contain various metals that can increase metal accumulation [12]. Thus, the present study determined Pb, Cd, Hg, As, Ni, Cr, Cu, Zn, and Co concentrations in the liver and kidneys of cattle from an agricultural area in Zambia to provide a preliminary assessment of metal accumulation in cattle offal, and the potential risks to human consumers as cattle liver and kidneys are widely consumed in Zambia.Paired liver and kidney samples were collected in October, 2009 from 112 mixed breed male and female adult cattle slaughtered at abattoirs in Lusaka (latitude 15° 25' S, longitude 28° 16' E), the capital city of Zambia. Cattle slaughtered at these abattoirs came from commercial farms in the Chisamba agricultural block, located approximately 50 km north of Lusaka City. Samples were transported to the Graduate School of Veterinary Medicine, Hokkaido University, Japan for metal concentration analysis.Metals (except for Hg) were extracted from the liver and kidney samples by acid digestion using the method of Nakayama [7] with minor modifications. Th...

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