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EFFECTS OF HEAVY METAL ON HUMAN RESPIRATORY SYSTEM

CHAPTER ONE

INTRODUCTION AND LITERATURE REVIEW

1.1    INTRODUTION

Heavy metals include both non-toxic and toxic elements. Iron (Fe), Cobalt (Co) Copper (Cu) Manganese (Mn) Molybdenum (Mo) and Zinc (Zc) Magnesium(Mg) are the trace elements and are required in a very minute amount, whereas other metals are non-essential, toxic to animals and even fatal when accumulated these metals includes; Mercury (Hg), Arsenic (As), Lead (Pb) Plutonium (Pu), Vanadium (v), Tungsten (w) and Cadmium (Cd), (Deevikaet al., 2012).  Heavy metals with established toxic action to humans include cadmium (Morrow, 2010 and Hayes, 2007) lead (Eric, 2013 and Patrick, 2006 and mercury (Bojorklund, 1995).Each of these has been studied in isolation for toxicity (Morrow, 2010; Patrick,2006 and Clarkson, and Magoss. 2006). But in the ecosystem, be it air, (atmosphere, land and water) where they occur they do not exist in isolation. They occur in close association with other metal and non-metallic elemental pollutants. Among the metallic pollutant could be calcium, copper, zinc, magnesium, manganese, iron and others. Metals are known to interact with one another. Interaction can bring about two element together include proximately and could cause out right displacement with one another. When ingested in food and water they can antagonize each other. When it comes to intestinal hand and pulmonary absorption it is there   conceivable that the presence of other element can affect the toxic potential of each of the heavy metal that has been study in isolation.

Egborge (1994) reported that Warri River had and unacceptability high cadmium level, 0.3mg/l of H2O, was 60-fold above the maximal allowable level of 0.005mg/l. This report prompted our early studies on the hepato-, nephro-  and  goladal toxicity  of cadmium in rat expose to this high close via water and diet. The diet was formulated with fish expose to 0.3mgCd/water in the ambient water, as protein source and the toxic effects investigated and reported. (Asagba and Obi, 2000; Asagba and Obi, 2001; Obi and Ilori, 2002; Asagba and Obi, 2004a; Asagba and Obi, 2004b; Asagba and Obi, 2005). The  studies focus on cadmium without taken into consideration the fact that other metal were also present the river water and as such were co-consumed by the communities using the river water for cooking  drinking and other domestic purposes. Hence it is desirable to know if the presence of other metal would enhance or diminish the toxic potential of cadmium or indeed that of any other metal such as lead that was mention above. Therefore the aim of this present studies was to re-examine the toxic potential of cadmium in the presence of other metals such as magnesium.  The objective set out to achieve were:

v Re-examination of the kidney toxicity of cadmium using established toxicity index for kidney such as Creatinine, Blood urea nitrogen and Alkaline phosphatase.

v Re-examine the status of the parameters in the absence of cadmium but in the presence of magnesium.

v Re-examine this parameterin the presence of cadmium and magnesium.