TABLE OF CONTENTS

Title Page    –         –         –         –         –         –         –         –         –         i

Certification          –         –         –         –         –         –         –         –         ii

Dedication   –         –         –         –         –         –         –         –         –         iii

Acknowledgements         –         –         –         –         –         –         –         iv

Table Contents      –         –         –         –         –         –         –         –         v-vii

CHAPTER ONE

1.0 INTRODUCTION           –         –         –         –         –         –         1-3

CHAPTER TWO

2.0  TRACE METALS AND THEIR TOXICITY MECHANISM

2.1     Arsenic        –         –         –         –         –         –         –         –         4-5

2.1.1 Toxicity Mechanism of Arsenic           –         –         –         –         5-6

2.2     Lead –         –         –         –         –         –         –         –         –         6-7

2.2.1 Toxicity Mechanism of Lead     –         –         –         –         –         7-9

2.3     Mercury       –         –         –         –         –         –         –         –         9-10

2.3.1 Toxicity Mechanisms of Mercury –     –         –         –         –         10-11

2.4     Cadmium     –         –         –         –         –         –         –         –         11

2.4.1 Toxicity Mechanism of Cadmium       –         –         –         –         12

2.5     Chromium   –         –         –         –         –         –         –         –         12-14

2.5.1 Toxicity Mechanism of Chromium      –         –         –         –         14-15

2.6     Iron – –         –         –         –         –         –         –         –         –         15

2.6.1 Toxicity Mechanism of Iron      –         –         –         –         –         16

CHAPTER THREE

3.0  HEALTH  EFFECTS  OF  TRACE  METALS

3.1     Arsenic and its Health Effects   –         –         –         –         –         17

3.2     Lead and its Health Effects        –         –         –         –         –         17-18

3.3     Mercury and its Health Effects  –         –         –         –         –         18-19

3.4     Cadmium and its Health Effects          –         –         –         –         19

3.5     Chromium and its Health Effects         –         –         –         –         20

3.6     Iron and its Health Effects –       –         –         –         –         –         20-21

CHAPTER FOUR

4.0     SUMMARY, CONCLUSION AND RECOMMENDATION

4.1     Summary     –         –         –         –         –         –         –         –         22

4.2     Conclusion –         –         –         –         –         –         –         –         22-23

4.3     Recommendation   –         –         –         –         –         –         –         23

References

CHAPTER ONE

1.0 INTRODUCTION

Metals are substances with high electrical conductivity, malleability and luster which voluntarily lose their electrons to form cations.  Metals are found naturally in the earth’s crust and their compositions vary among different localities, resulting in spatial variations of surrounding concentrations. The metal distribution in the atmosphere is monitored by the properties of the given metal and by various  environmental factors (Khlifi and Hanza- Chalfia, 2010). Trace metals are generally referred to as those metals which possess a specific density of more than 5g/cm³ and adversely affect the environment and living organisms (Jarup, 2003). These metals are quite essential to maintain various biochemical and physiological functions in living organisms when in very low concentrations, however, they becomes noxious when they exceed certain threshold concentrations. Trace metals are significant environmental pollutants and their toxicity is a problem of increasing significance for ecological, evolutionary, nutritional and environmental reasons (Jaishanka et al., 2014). The most commonly found metals in waste water include Arsenic, Cadmium, Chromium, copper, lead, Nickel and Zinc, all of which causes risks for human health and the environment (Lambert et al., 2000). Trace metals enter the surroundings by natural means and through human activities. Various sources of trace metals include soil erosion, natural weathering of the earth’s crust, mining, industrial effluents, urban run-off, savage discharge, insects or disease control agents applied to crops and many others (Morals et al., 2012).

Although, these metals have crucial biological function in plants and animals, sometimes their chemical combination and oxidation-reduction properties have given them an additional benefits so that they can escape control mechanisms such as homeostasis, transport, compartmentalization and binding to required cell constituents. These metals bind with protein sites which are not made for them by displacing original metals from their natural binding sites causing malfunctioning of cells and untimely toxicity. Previous research has found that oxidative deterioration of biological macromolecules is primarily due to binding of trace metals to the Deoxyribonucleic acid (DNA) and nuclear proteins (Flora et al., 2008).