ABSTRACT

 The concentration of heavy metals such as Pd, Cd, Cu and Cr were studied using AAS on vegetable samples such as Tomato (fruit and leaf) and Onion bulb. Trace element as Cu showed high concentration. The concentration of heavy metal like Cu ranged from of 0.155 to 0.024mg/kg in tomato fruit; 0.120 to 0.057mg/kg in leafy tomato; 0.118 to 0.121mg/kg in onion bulb which were more than the maximum permissible limit according to the International organization like FAO and WHO. The concentration of Cd for the vegetable samples ranged from 0.013 to 0.005mg/kg in tomato fruit; 0.015 to 0.027mg/kg in leafy tomato; 0.005 to 0.006mg/kg in onion bulb which were below the permissible limit. The concentration of the remaining heavy metals as Cr ranged from 0.506 to 0.568mg/kg in tomato fruit; 0.610 to 0.567mg/kg in leafy tomato; 0.510 to 0.608mg/kg in onion bulb respectively and Pb ranged within 0.175 to 0.219mg.kg in tomato fruit; 0.080 to 0.021mg/kg in leafy tomato; 0.102 to 0.064mg/kg in onion bulb respectively were within the permissible limit as compared with the (FAO/WHO, 2001). The high level of Copper (Cu) in vegetable samples, are suspected for liver and kidney damage, anemia and many more health risks. Samples selected for the study are highly contaminated with Cu which may possess a major health concern from the research.

KEYWORDS:Heavy metals, Vegetables, health risks, FAO/WHO limits, Tomato (fruit and leaf), Onion bulb, Contamination, Permissible limits.TABLE OF CONTENTS

DECLARATION.. i

CERTIFICATION.. ii

DEDICATION.. iii

ACKNOWLEDGMENT. iv

ABSTRACT. v

CHAPTER 1. 1

1.0 INTRODUCTION.. 1

1.1 STATEMENT OF THE PROBLEMS. 3

1.2 JUSTIFICATION.. 4

1.3 AIM AND OBJECTIVES. 5

CHAPTER TWO.. 6

2.0 LITERATURE REVIEW... 6

2.1 OCCURRENCE AND EMISSION OF HEAVY METALS. 6

2.1.2 Routes OF Heavy Metal Exposure. 7

2.1.3 Classification of Heavy Metal Exposure. 7

2.1.4 Hazardous Effects of Heavy Metals ON Human Health. 9

2.1.5 Hazards OF Heavy Metals Contamination. 10

2.2 HEAVY METALS IN VEGETABLES. 10

2.3 ENVIRONMENTAL CONTAMINANTS. 14

2.4 EFFECT OF HEAVY METALS ON HUMAN HEALTH.. 15

2.5 BENEFICIAL HEAVY METALS. 16

2.6 TOXICITY OF HEAVY METALS. 17

2.7 ROLE OF HEAVY METALS TO HUMAN HEALTH.. 18

2.7.1 Copper (Cu) 18

2.7.2 Lead (Pb) 19

2.7.3 Cadmium (Cd) 21

2.7.4 Chromium (Cr) 21

2.8 CHEMISTRY OF TOXICITY.. 22

2.9 HUMAN EXPOSURE THROUGH FOOD, AIR AND WATER.. 22

2.9.1 Atomic Absorption Spectroscopy: 23

CHAPTER THREE.. 24

3.0 MATERIALS AND METHOD.. 24

3.1 Reagents: 24

3.1.2 Apparatus: 24

3.2.2 Sampling. 25

3.2.3 Preparation of Vegetable Samples. 25

3.2.4 Digestion procedure (Buchaure, 2002) 25

3.2.5 Determination by Atomic Absorption Spectrophotometer 26

3.2.6 Principle. 26

CHAPTER FOUR.. 28

4.0 RESULTS AND DISCUSSION.. 28

4.1 RESULTS. 28

4.1 DISCUSSION.. 32

CHAPTER FIVE.. 35

5.0 CONCLUSION AND RECOMMENDATION.. 35

5.1 CONCLUSION.. 35

5.2 RECOMMENDATION.. 35

REFERENCES. 37

APPENDIX I. 46

APPENDIX II. 46

APPENDIX III. 47

APPENDIX IV.. 47

APPENDIX V.. 48

LIST OF FIGURES

Figure: 4.1 Mean concentrations of copper in vegetable samples……………………….28

Figure 4.2: Mean concentrations of cadmium in vegetable samples…………………….29

Figure 4.3: Mean concentrations of chromium in vegetable samples…………………...30

Figure 4.4: Mean concentrations of Pb in vegetable samples…………………………...31

Figure 4.5: Comparison of mean concentrations of heavy metals in vegetable samples.32 (tomato fruits, tomato leaves and onion bulbs) with FAO/WHO standard limits.