ABSTRACT
The Levels of lead (Pb), cadmium (Cd) and chromium (Cr) in blood, urine, nail and hair samples of electronic repairers in Kaduna-Nigeria were assessed using Atomic Absorption Spectrophotometry (AAS). The mean blood concentrations of Pb, Cd and Cr in the subjects were 29.33 ± 4.80, 7.78 ± 10.57 and 24.78 ± 21.77 μg/dL, respectively. The mean urine concentrations of Pb, Cd and Cr were 24.18 ± 2.98, 6.81 ± 10.05 and 14.78 ± 14.20 μg/dL, respectively. Mean nail metal values of 37.13 ± 4.08, 1.00 ± 1.21 and 18.49 ± 12.71 μg/g were obtained for Pb, Cd and Cr, respectively while mean hair metal values of 39.41 ± 5.63, 1.09 ± 1.14 and 19.13 ± 11.61 μg/g for Pb, Cd and Cr, respectively. Positive Pearson correlation coefficients were also observed between Pb/Cd, Pb/Cr and Cd/Cr in all samples and they indicate the metals are likely from same pollution source. The mean concentrations of the metals in all samples were higher than the WHO, ILO and ACGIH standards, implying the repairers are occupationally exposed and are subject to serious health concerns. Smoking was suspected to significantly affect the concentrations of these metals. The level of education, use of safety devices, period of exposure (length of period in the job), the type of electronics and the age of the electronic repairers were also suspected to remarkably affect the concentrations of the metals. However, the sources of food eaten at work were found to have no significant effects on the levels of the metals present.
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TABLE OF CONTENTS
Title Page Title page i Declaration ii Certification iii Dedication iv Acknowledgement v Abstract vi Table of Contents vii List of Tables xii List of Figures xiii List of Appendices xv Glossary and Abbreviations xvii CHAPTER ONE INTRODUCTION
1.1 Background of the Study 1
1.2 Research Problem 4 1.3 Justification for the Study 5 1.4 The Research Questions 6 1.5 The Research Hypotheses 6
1.6 Significance of the Study 7
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1.7 Aim and Objectives of the Study 8 1.8 Scope and Limitation of the Study 8 CHAPTER TWO LITERATURE REVIEW 2.1 Occupational Health 10 2.2 Occupational Health and Exposure to Heavy Metals in Developing Countries 11 2.3 Occupational Health and Exposure to Heavy Metals in Nigeria 14 2.4 Heavy Metals in the Work Place 19 2.4.1 Lead (Pb) in the work place 19 2.4.2 Cadmium (Cd) in the work place 23 2.4.3 Chromium (Cr) in the work place 25 2.5 Occupational Hazards of Electronic Repairers 26 2.6 The Use of Biomarkers to Detect and Quantify Heavy Metals Exposure 27 2.7 Toxic Metal Detection in Biological Samples 31 CHAPTER THREE MATERIALS AND METHODS 3.1 Preparation of Solutions 33 3.1.1 Stock Solutions 33 3.1.2 Standard Working Solutions 33 3.2 Description of the Study Area 34
3.2.1 Hayin Banki (1) 35
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3.2.2 Ungwar Dosa (2) 35 3.2.3 Badarawa (3 & 4) 35 3.2.4 Ungwar Mu‘azu (5) 35 3.2.5 Doka (6) 36 3.2.6 Ungwar Kanawa (7) 36 3.2.7 Kawo (8) 36 3.2.8 Malali (9) 36 3.2.9 Ungwar Rimi (10) 36 3.3 Sample Collection 48 3.3.1 Blood samples 48 3.3.2 Urine samples 48 3.3.3 Hair samples 48 3.3.4 Nail samples 48 3.4 Sample Preparation and Analysis 49 3.4.1 Sample pre-treatment and digestion 49 3.4.1.1 Blood and urine samples 49 3.4.1.2 Hair samples 49 3.4.1.3 Nail samples 50 3.4.2 Determination of the metals 50 3.5 Quality Assurance Procedure 50
3.5.1 Preparation of multi-element standard solution (MESS) 51
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3.5.2 Recovery experiment 51 3.6 Statistical Analysis 53 CHAPTER FOUR RESULTS 4.1 Quality Assurance (Recovery Experiment) 54 4.2 Results Pb, Cd and Cr Analyses in Blood Samples of Subjects 55 4.3 Results of Pb, Cd and Cr Analyses in Urine Samples of Subjects 56 4.4 Results of Pb, Cd and Cr Analyses in Nail Samples of Subjects 57 4.5 Results of Pb, Cd and Cr Analyses in Hair Samples of Subjects 58 4.6 Correlation of Each Metal across the Blood, Urine, Nail and Hair Samples 59 4.7 Concentration of Pb, Cd and Cr in the Subjects by Differrent Categories 63 4.7.1 Concentration of Pb, Cd and Cr in the test subjects by social habits (smoking) 63 4.7.2 Concentration of Pb, Cd and Cr in the test subjects by education 64 4.7.3 Concentration of Pb, Cd and Cr in the test subjects by type of electronics 65 4.7.4 Concentration of Pb, Cd and Cr by use of protective devices 66 4.7.5 Concentration by length of period in the job 67 4.7.6 Concentration by the source of food eaten at work and age of the repairers 68 CHAPTER FIVE DISCUSSION
5.1 Concentrations of Pb, Cd and Cr in Blood Samples of the Subjects 71
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5.2 Concentrations of Pb, Cd and Cr in Urine Samples of the Subjects 72 5.3 Concentrations of Pb, Cd and Cr in Nail Samples of the Subjects 73 5.4 Concentrations of Pb, Cd and Cr in Hair Samples of the Subjects 75 5.5 Correlation of Each Metal across the Blood, Urine, Nail and Hair Samples 76 5.6 Concentration of Pb, Cd and Cr in the Subjects by Differrent Categories 78 5.6.1 Concentration of Pb, Cd and Cr in the test subjects by social habits (smoking) 78 5.6.2 Concentration of Pb, Cd and Cr in the test subjects by education 79 5.6.3 Concentration of Pb, Cd and Cr in the test subjects by type of electronics 80 5.6.4 Concentration of Pb, Cd and Cr by use of protective devices 81 5.6.5 Concentration by length of period in the job 81 5.6.6 Concentration by the source of food eaten at work and age of the repairers 82 CHAPTER SIX SUMMARY, CONCLUSION AND RECOMMENDATION 6.1 Summary and Conclusion 84 6.2 Recommendation 84 References 87 Appendices 113
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CHAPTER ONE
INTRODUCTION 1.1 Background of the Study People engage in diverse occupations in order to achieve some set goals; the primary of which usually is to earn a living. These occupations may range from unskilled, semi skilled to skilled occupations. A vast population of people fall under the semi-skilled category especially in developing countries of Asia and Africa. The dominant mode of training is through apprenticeship, a system of training a new generation of practitioners of a structure competency based set of skills. Most of the training here is done while working for an employer who helps the apprentices learn their trade or profession, in exchange for their continuing labour for an agreed period after they have achieved measurable competency. Examples of occupations under this category are electronic repairers, mechanics, carpenters, painters, welders, and so forth. Most people under this category are either illiterate or semi literate usually with little or no formal training or education. In the developing world, employment in the informal sector may reach 70 percent, with the contribution to the gross domestic product (GDP) ranging from 10 to 60 percent (ILO, 2002) Virtually all occupations have some level of hazards inherent in them. Occupational health has been an issue of cognisance since the 1950 with a joint committee of the International Labour Organization (ILO) and the World Health Organization (WHO) sharing a common definition of occupational health at its first session in 1950.
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According to the World Health Organization (WHO) report in 1998, there were about 250 million cases of work related injuries through the year worldwide (WHO, 1998). More recent reports estimates work related diseases at 160 million every year while more than 2.2 million occupational deaths and 250 million industrial accidents occur every year worldwide (Bankole and Ibrahim, 2012; ILO, 2011). Work accidents or occupational accidents constitute an important cause of sickness and absence from work in industries particularly in developing countries (Asogwa, 1978), thereby causing huge losses in revenue for the government. These hazards could be as a result of materials, equipment and appliances frequently used or some form of physical energy demanding stage or stages or the working environment. These hazards could be electrical in nature, chemical, physical or radioactive. Electronic repairers like their counterparts in other occupations are exposed to various occupational hazards which could be classified as follows:
 Electrical hazards: electrical shock, electrocution, and so forth
 Chemical hazards: lead fumes and dust, lead ingestion, fumes from heated solder constituents, fumes from decomposition products from heating of oil, paints or coatings present on the surfaces heated during soldering, fumes from fluxes, gases and vapour from cleaning agents.
 Physical hazards: burns and fire.
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 Risk of radioactivity: radioactivity from some USA-made common voltage regulator tubes which had radioactive isotopes added, apparently to achieve more stable operation.
Both electronic and hard soldering present potential exposure issues via airborne, skin contact and hand to mouth routes, from both the products used or by- products of the soldering process. There are also physical hazards from heat and in some cases from open flame (Manton and Malloy, 1983). There are virtually no published data on the statistics of electronic repairers and the cases of occupational accidents amongst them in Nigeria. According to the International Labour Organization, approximately 35 metals are of major concern in regard to occupational exposure. Two thirds of them can cause health hazards if not properly handled and may result in well-defined toxic effects in humans. Some metals are not poisonous in small amounts and may, on the contrary, be necessary for good health. On the other hands, some metals, even in small doses, may cause both immediate and chronic poisoning. Damage may involve disturbances of the blood composition or nervous system, or injury to the liver or kidneys. Long-term exposure to certain metal compounds may cause cancer. Allergic reactions may result from repeated long term contact with some metals and metal compounds.
Mercury, lead, cadmium, nickel, chromium, manganese, arsenic, antimony, zinc, copper, cobalt, vanadium and beryllium are used in industries and are known to cause adverse health effects both as the metal and as metallic compounds. Cadmium and chromium [VI] are listed by the International Agency for Research on Cancer (IARC) as carcinogenic to humans while lead is classified as possibly carcinogenic to humans.
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1.2 The Research Problem Occupations are a major source of exposure to heavy metals to adults; these occupations are an integral part of human lives since survival is heavily dependent on them. Thirty-eight per cent of the male working population in Nigeria are engaged in agriculture (20% of women) and 56% of the female working population are engaged in sales and service occupations (19% of men). Twenty-one per cent of men and 9% of women are engaged in skilled manual trades and 16% of men and 8% of women in professional and technical jobs (NPC and ORC Macro, 2004). No matter how small the fraction of these metals that pose a threat at the work place, it becomes obviously dangerous considering that most people normally engage in such occupations for a substantial part of their lives (usually to old age) and spend more than 8 hours a day at work especially in poor developing countries. Common symptoms of patients frequently reported at hospitals in Nigeria may be as a result of exposure to heavy metals, often scrutiny for heavy metals exposure is not usually considered.
Electronic repairers are exposed to lead (Pb) from solder fumes and dust, cadmium (Cd) and chromium (Cr) from batteries, coatings, pigments etc. These metals could pose serious health problems over a long period and could indirectly affect children at home as ‗take home metals‘ on clothing, bags e.t.c. The level of adherence to safety measures at work due primarily to ignorance and poverty even makes the problem a bigger one. Poor statistics available on the level of these metals in electronic repairers in Nigeria does not make glaring the impending problem in the job, making also awareness about the problem low or nonexistent.
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1.3 Justification for the Study Exposure to lead, cadmium and chromium at work is an issue of concern especially in developing countries like Nigeria where the level of education and awareness about hazardous metal exposure is low and poverty is high (98% of adults and 99% of children affected by exposure to lead live in low- and middle-income countries (WHO, 2009)). Many research reports have shown serious exposure of workers in artisan professions to heavy metals. Welders have been reported to be exposed to heavy metals (Sabitu et al., 2009), auto mechanics (Babalola et al., 2005 and Dioka et al., 2004), painters (Orisakwe et al., 2007), drivers (Fatoki and Ayoade, 1996) e.t.c have also been reported to be exposed to heavy metals. With a lot of researches conducted on different occupations to assess hazards and exposure, there are no reported studies on occupational exposure of electronic artisans, hence this study was conceived. The study is focused at assessing the level of exposure of the repairers to lead (Pb), cadmium (Cd), chromium (Cr) and habits affecting the level of exposure. Nigeria, just as most other developing countries lacks accurate and up to date statistical figures on occupational exposure to lead, cadmium and chromium. There is the need to provide such statistics to facilitate analyses on occupational health in Nigeria and would come handy in the formulation and/or amendment of policies affecting such occupations.
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1.4 The Research Questions The questions that could arise from this study are;
1. What are the levels of lead, Cadmium and Chromium exposures in electronic repairers in the study area?
2. Are the levels of the metals higher than allowed?
3. What is the relationship between the level of exposure of the repairers with their social and personal habits?
4. What is the correlation between the metals and are the metals likely from same pollution source?
5. What nature of sensitization should be undertaken to educate electronic repairers of the hazards in the profession?
1.5 Aim and Objectives of the Study This study is aimed at assessing the levels of lead, cadmium and chromium in blood, urine, nail and hair samples of electronic repairers in Kaduna metropolis, Nigeria, with a view to comparing the results obtained with the international allowed limits for lead (Pb), cadmium (Cd) and chromium (Cr) in the body. This shall be achieved through the following objectives:
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i) To collect blood, urine, nail and hair samples from electronic repairers and to analyze the samples collected for Pb, Cd and Cr in order to determine levels and therefore exposure.
ii) To correlate the levels of the metals in the samples and ascertain whether the metals are likely from same source.
iii) To compare the concentrations of the metals with WHO and ILO acceptable limits to determine whether the repairers are at risk or not.
iv) Assess the effect of factors like smoking, drinking, age, length of period in the job, the brand of electronics specialized in, adherence to safe practice and level of formal education on the concentrations of the metals in the repairers.
1.6 The Research Hypotheses The study was guided by the following hypotheses:
a) The null hypothesis (H0) which states that:
i) The levels of the metals (Pb, Cd and Cr) in the system of the electronic repairers in Kaduna metropolis, Nigeria are within the WHO acceptable levels and the repairers are therefore, not at risk.
ii) There is no correlation between the metals in the system of the electronic repairers and are likely not from same pollution source.
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iii) Personal and social habits do not significantly affect the levels of the metals.
b) The alternate hypothesis (H1), which states that:
i) The levels of the metals (Pb, Cd and Cr) in the system of the electronic repairers in Kaduna metropolis, Nigeria exceed the WHO acceptable levels and the repairers are therefore at risk.
ii) There is a positive correlation between the metals in the system of the electronic repairers; the metals are likely from same pollution source.
iii) Personal and social habits significantly affect the levels of the metals.
1.7 Significance of the Study The study would provide data on occupational exposure of electronic repairers to heavy metals. The result of the research would further guide the government in policy making with respect to occupational issues. The relationship between the level of occupational hygiene of the repairers and the levels of the metals would also give an indication of the exposure risk of the family members in form of ‗take home‘ metals 1.8 Scope and Limitation of the Study
This study is aimed at assessing the levels of lead, cadmium and chromium exposures in electronic repairers in Kaduna metropolis, Nigeria. Cooperation from
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electronic repairers to willingly participate in the research was very low; most of them have this superstitious believe of anything that has to do with blood is evil and hence were not ready to submit themselves for collection of samples. Environmental conditions were not taken into account during the research work, as the conditions would have little or no effect on the microenvironment of the repairers (working area).
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