TABLE OF CONTENTS

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

Certification-          –         –         –         –         –         –         –         –         ii

Dedication-  –         –         –         –         –         –         –         –         –         iii

Acknowledgements-        –         –         –         –         –         –         –         iv

Table of Contents- –         –         –         –         –         –         –         –         v-vi

CHAPTER ONE

1.0 Introduction- –         –         –         –         –         –         –         1-3

CHAPTER TWO

2.0     Sources and Emission of Heavy Metal-         –         –         –         4-5

2.1     Mode of Exposure to Heavy Metals-    –         –         –         –         6-9

2.2.1  Arsenic-       –         –         –         –         –         –         –         –         9-11

2.2.2  Cadmium-    –         –         –         –         –         –         –         –         11-12

2.2.3  Mercury-     –         –         –         –         –         –         –         –         12-14

2.2.4  Copper-       –         –         –         –         –         –         –         –         14-17

2.2.5  Lead- –         –         –         –         –         –         –         –         –         17-18

CHAPTER THREE

3.1     Health Effect of Heavy Metal in Humans-     –         –         –         19

3.1.1  Arsenic-       –         –         –         –         –         –         –         –         19-20

3.1.2  Cadmium-    –         –         –         –         –         –         –         –         20-23

3.1.3  Lead- –         –         –         –         –         –         –         –         –         23-24

3.1.4  Mercury-     –         –         –         –         –         –         –         –         25-27

CHAPTER FOUR

4.0     Summary and Conclusion-        –         –         –         –         –         28

4.1     Summary-    –         –         –         –         –         –         –         –         28-29

4.2     Conclusion- –         –         –         –         –         –         –         –         29

             References

CHAPTER ONE

1.0     INTRODUCTION

There are around thirty chemical elements that play a pivotal role in various biochemical and physiological mechanisms in living organisms, and recognized as essential elements for life. In fact, for many food components, the intake of metal ions can be a double edged sword. Majority of the known metals and metalloids are very toxic to living organisms and even those considered as essential, can be toxic if present in excess. Concentrations of several toxic metal and metalloids have been largely increased as a result of human activities. They can disturb important biochemical processes, constituting an important threat for the health of plant and animals. Plants and animals absorb these elements from soils, sediments, and water by contact with their external surfaces, through ingestion and also from inhalation of airborne particles and vaporized metals (Mudgal et al., 2010). The requirement for ingestion of trace metals such as Fe and Cu ions to maintain normal body functions such as the synthesis of metallo-proteins is well established. However, cases of excess intake of trace metal ions are credited with pathological events such as the deposition of iron oxides in Parkinson’s disease (Cetina et al., 2006). In addition to aiding neurological depositions, these redox active metals ions have been credited with enhancing oxidative damage, a key component of chronic inflammatory disease (Umanzor et al., 2006) and a suggested initiator of cancer (Elst et al., 2007). As inflammation is a characteristic feature of a wide range of diseases, further potential pathological roles for metal ions are emerging as exemplified by premature ageing (Carbello et al., 2008).

For the maintenance of health, a great deal of preventative measures is in place to avoid ingestion of potentially toxic metal ions. From monitoring endogenous levels of metal ions in foods and drinks to detecting contamination during food preparation, European countries spend significant resources to avoid metal intake by the general population (Hida et al., 2002). From a therapeutic viewpoint, considerable research and development efforts are being exerted to discorporate metal ions from the body. Since the use of As in World War I, researchers have advanced methods to discorporate toxic metals ions (Piazza et al., 2009). More recently efforts have moved to eradicate neurological deposits and reverse redox active metal ion contributions to oxidative stress. The latter approach has a focus on chelators that reverse the potential detrimental effects by generating anti-oxidant enzyme mimetics upon chelating the labile redox-active metal ion. Intriguingly, some very good candidates for anti oxidant prodrug chelators are common food constituents such as catechins (Aggarwal and Shishodia, 2006).

Metallic elements are intrinsic components of the environment. Their presence is considered unique in the sense that it is difficult to remove them completely from the environment once they enter in it. Metal constitute an important class of toxic substance which are encountered in numerous occupational and environmental circumstances. The impact of these toxic agents on human health is currently an area of intense interest due to the ubiquity of exposure.

With the increasing use of a wide variety of metals in industry and in our daily life, problems arising from toxic metal pollution of the environment have assumed serious dimensions.