الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 157 |  |  |
| | | from | 157 | | |
Abstract
The present study was conducted to determine the residual amounts of heavy metals ( cadmium , lead , mercury and zinc; the most frequently in the environment) in muscle, liver , kidney and spleen of cattle slaughtered at the local abattoir of Zagazig city. In order to evaluate influence of age and sex on heavy metal accumulation, four groups of cattle carcases ( five of each) were utilized after being examined for age and sex. Those cattle with milky teeth or changed the two central incisor teeth (1.9 - 2 years) were considered young , but those changed all incisor teeth were placed in the aged groups. Specimens were grouped according to the age and sex of examined animals into 4 groups : group 1( young male), group 2 ( young female), group 3 ( aged male)and group 4 ( aged female) . Tissue samples including muscle, liver, kidney and spleen (20 gm of each ) were collected from tissues and organs of examined cattle . Individual samples were immediately transmitted to the laboratory in polyethylene bags with its identifications ( type of tissue , sex and age of cattle) .
Samples ( one gram each) were subjected for wet digestion procedure in screw capped tubes using nitric and perchloric acid mixture (3 : 2) . The tubes, following overnight incubation at room temperature, were placed in a water bath set at 70°C for 3 hours to ensure complete digestion without loss of mercury (volatile at higher temperature) . The digest was diluted with 5 ml deionized water and filtered with Whittman filter paper. The filterate was used to determine cadmium (Cd), lead (Pb) , mercury (Hg) and zinc (Zn) residues by means of Atomic Absorption spectrophotometer (AAS). The results were calculated as milligram metal per kilogram wet matter (mg/kg w/w basis).
It can be concluded that excessive use of sewage sludge as pasture top dressing or phosphatic fertilizers (superphosphate) together with environmental pollution from industrial and agricultural activities or mining and smelting sources elevated levels of heavy metals ( especially lead and cadmium) in animal tissues. Also, it can be concluded that liver and kidney especially of aged cattle were the organs mostly under risk and accumulate high level of heavy metal residues . Thus, consumption of these organs should not be recommended.