Physico-Chemical And Heavy Metals Assessment Of ‘Nzu Clay’ And Its Effect On Hairs Of Consumers

TABLE OF CONTENTS

Title page i

Cover page iii

Declaration iv

Certification v

Dedication vi

Acknowledgement vii

Abstract viii

CHAPTER ONE

1.0 INTRODUCTION 1

1.1 Clay 1

1.2 ‗Nzu Clay‘ 1

1.3 Some of the Proffered Reasons for Geophagy in Humans 3

1.4 History of Clay 5

1.5 Physical and Chemical Properties of Clay 7

1.6 Uses of cay 9

1.7 Radionuclides of Specific Interest in Clays and the Environment 11

1.7.1 Pathways of radionuclides in the environment 12

1.7.2 Hazardous radionuclides and their impacts on human health 13

1.8 Gamma-ray Spectroscopy 15

1.8.1 Assessments of radioactivity levels 17

1.8.2 Biomonitor of Accumulated Heavy Metals in Human 17

1.9 Justification for the Study 18

1.10 Aim and Objectives of the study 19

CHAPTER TWO

2.0 LITERATURE REVIEW 21

2.1 Kaolin 21

2.2 Organoleptic and Granulometric Properties of Edible Clays 24

2.2.1 Cation exchange capacity 24

2.2.2 Bulk density 24

2.2.3 Water absorption index of the clay 25

2.2.4 Dispersibility of the clay 25

2.3 Heavy Metals in Clay 26

2.3.1 Arsenic 27

2.3.2 Chromium 27

2.3.3 Lead 29

2.3.4 Nickel 29

2.3.5 Zinc in clay samples 29

2.4 Health Impact of Heavy Metal 31

2.4.1 Arsenic 31

2.4.2 Cadmium 32

2.4.3 Lead 32

2.5 Radioactivity in Soil, Clay, Sand Samples 33

2.6 Selected Instrumentation Used in the Study 39

2.6.1 Theory and Instrumentation of X-Ray Diffraction Analysis 39

2.6.2 Procedure for XRD analysis 40

2.7 Theory and Instrumentation of Hyper Pure Gammanium Detector For

Radioactivity Measurement 41

2.7.1 Hyper-pure germanium detector configuration 42

2.7.2 Planar configuration 42

2.7.3 Electric field and capacitance 44

2.7.4 Operational characteristics of HPGe 45

2.7.5 Energy resolution 46

2.8 Theory and Instrumentation of Atomic Absorption Spectroscopy for Metal

Analysis 47

2.9 Structure of Hair 49

2.9.1 Hair as a superior bio-indicator of heavy metals compared to blood and

urine 50

2.9.2 Hair analysis as a tool in assessing human exposure to heavy metals through geophagy and the limitations 52

CHAPTER THREE

3.1 MATERIALS 55

3.1.1 List of apparatus/equipments 55

3.1.2 List of reagent 55

3.1.3 Sampling of the clay types 56

3.2 Method 58

3.2.1 Quality assurance/Preparation of standard solution 58

3.2.2 Sampling of hair from addicted and non-addicted consumers of ‗Nzu clay‘ 60

3.2.2a Processing of raw ‗Nzu Clay‘ Sample 60

3.2.2b Sample preparation 62

3.2.3 Determination of some physico-chemical properties of the ‗Nzu Clay‘ samples 62

3.2.4 Determination of the cation exchange capacity of the clay by the Bacl

2 compulsive exchange method 65

3.2.5 Digestion of ‗Nzu clay‘ Samples for determination of total Cd, Cr, Cu, Ni, Pb

and Zn contents 66

3.2.6 Measurement of the radioactivity in the clay samples 68

3.2.6 Radiation hazard indices 69

3.2.7 X-ray diffraction analysis of the ‗Nzu Clay‘ samples using X-ray diffractometer 73

3.2.8 Statistical analysis 74

CHAPTER FOUR

4.0 RESULTS 75

CHAPTER FIVE

5.0 DISCUSSION 91

5.1 Physicochemical Parameters of the Raw and Processed/Finished ‗Nzu clay‘

Samples 92

5.1.1 Correlation between similar physiochemical properties of the various

sampling sites 96

5.2 Heavy metals concentration in ‗Nzu clay‘ and in the hair of addicts and non

addicts 97

5.2.1 Concentration of Arsenic in hair of addicts and in ‗Nzu clay‘ samples 97

5.2.2 Concentration of Cadmium in the ‗Nzu clay‘ samples and in hair of addicts 98

5.2.3 Concentration of Chromium in the ‗Nzu clay‘ samples and in hair of addicts 99

5.2.4 Concentration of Copper in the ‗Nzu clay‘ samples and in hair of addicts 100

5.2.5 Concentration of Nickel in the ‗Nzu clay‘ samples and in hair of addicts 101

5.2.6 Concentration of Lead in the ‗Nzu clay‘ samples and in hair of addicts 103

5.2.7 Concentration of Zinc in the ‗Nzu clay‘ samples and in hair of addicts 104

5.3 Concentration (Bq/kg) of Radioactive Elements in ‗Nzu clay‘ Samples 105

5.3.1 Level of the health risk hazard of radioactive elements in ‗Nzu Clay‘ samples 107

5.4 Mineral composition of ‗Nzu clay‘ by XRD method 110

CHAPTER SIX

6.0 SUMMARY, CONCLUSION AND RECOMMENDATION 111

6.1 Summary 111

6.2 Conclusion 113

6.3 Recommendation 115

REFERENCE 116