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Environmental Biomonitoring of Essential and Potentially Toxic Elements in Human Scalp Hair Using Accelerated Microwave-Assited Sample Digestion and Inductively Coupled Plasma Optical Emission Spectroscopy

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Environmental Biomonitoring of Essential and Potentially Toxic Elements in Human Scalp Hair
using Accelerated Microwave-Assisted Sample Digestion and Inductively Coupled Plasma
Optical Emission Spectroscopy
Hope Kumakli
North Carolina A&T State University
A thesis submitted to the graduate faculty
in partial fulfillment of the requirements for the degree of
MASTER OF SCIENCE
Department: Chemistry
Major: Chemistry
Major Professor: Dr. Sayo O. Fakayode
Greensboro, North Carolina
2016
Pro Q ue st Num b e r: 10131384
All rig hts re se rve d
INFO RMATIO N TO ALL USERS
The q ua lity o f this re p ro d uc tio n is d e p e nd e nt up o n the q ua lity o f the c o p y sub m itte d .
In the unlike ly e ve nt tha t the a utho r d id no t se nd a c o m p le te m a nusc rip t
a nd the re a re m issing p a g e s, the se will b e no te d . Also , if m a te ria l ha d to b e re m o ve d ,
a no te will ind ic a te the d e le tio n.
Pro Q ue st 10131384
Pub lishe d b y Pro Q ue st LLC (2016). Co p yrig ht o f the Disse rta tio n is he ld b y the Autho r.
All rig hts re se rve d .
This wo rk is p ro te c te d a g a inst una utho rize d c o p ying und e r Title 17, Unite d Sta te s Co d e
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ii
The Graduate School
North Carolina Agricultural and Technical State University
This is to certify that the
Thesis of
Hope Kumakli
has met the thesis requirements of
North Carolina Agricultural and Technical State University
Greensboro, North Carolina
2016
Approved by
Dr. Sayo O. Fakayode
Major Professor
Dr. Zerihun Assefa
Committee Member
Dr. Margaret Kanipes
Committee Member
Dr. Zerihun Assefa
Department Chair
Dr. Sanjiv Sarin
Dean, The Graduate School
iii
© Copyright by
Hope Kumakli
2016
iv
Biographical sketch
Hope hails from Ghana where he had both his high school and undergraduate education.
He attended Keta Senior High School in the Volta region of Ghana and he wrote West African
Senior Secondary School Certificate Examination (WASSCE) at Chemu Senior High School,
Tema. After high school graduation, he enrolled in the chemistry program at Kwame Nkrumah
University of Science and Technology Kumasi where he obtained his Bachelor of Science degree
in Chemistry. Hope has graduated the Master of Science program in chemistry at North Carolina
A & T State University.
Outside school activities, Hope is actively involved in church activities. He always loves
football and travelling to see new places.
v
Dedication
This thesis is dedicated to all my loved ones, whose love, advice, support and
encouragement gave me strengthen through the challenges of life and to all Master of Science
students in Chemistry Department.
vi
Acknowledgements
Horses and chariots are prepared for battle, but victory is the Lords (Psalm 21:31). My
greatest appreciation goes to almighty God, creator of the heavens and earth for his unflinching
love, protection, peace and blessings he has bestowed upon me. Father may your will be done in
my life.
To my family, I will forever be indebted to their financial and spiritual support and most
importantly their love.
My sincere gratitude goes to my research advisor Dr. Sayo O. Fakayode for painstakingly
mentoring and forging me into a better student.
To Dr. Zerihun Assefa and Dr. Margaret Kanipes, I say a very big and a loud thank you
for taking time off your busy schedules to read and correct my thesis. I also thank you for the
financial support provided to me during my graduate studies.
To Mr. Emmanuel Ampiah, Miss Tsdale Me research group for their constructive criticism and encouragement during my study at North
Carolina A & T State University.
vii
Table of Contents
List of Figures ............................................................................................................................... xii
List of Tables ............................................................................................................................... xiii
NOMENCLATURE ..................................................................................................................... xv
Abstract ........................................................................................................................................... 1
CHAPTER 1 Introduction............................................................................................................... 3
1.1 Background ........................................................................................................................... 3
1.2 Aim ........................................................................................................................................ 4
1.3 Specific Aims ........................................................................................................................ 4
1.4 Justification ........................................................................................................................... 4
1.5 Biology of the Human Scalp Hair ......................................................................................... 5
1.6 Hair Analysis ......................................................................................................................... 6
1.7 Biomonitoring of Environmental Elements and Chemicals of Concern ............................... 6
1.8 Use of Human Scalp Hairs as a Biomonitor and Biomakers ................................................ 6
1.9 Importance of Hair Analysis ................................................................................................. 6
CHAPTER 2 Literature Review .................................................................................................... 8
2.1 Trace Elements ...................................................................................................................... 8
2.2 Sources of Trace Elements and Tolerable Amounts in Humans ........................................... 9
2.3 Selenium (Se) ........................................................................................................................ 9
2.4 Calcium (Ca) ....................................................................................................................... 10
viii
2.5 Copper (Cu) ......................................................................................................................... 11
2.5.1 Toxicity of copper ........................................................................................................ 11
2.6 Zinc (Zn) ............................................................................................................................. 11
2.7 Magnesium (Mg) ................................................................................................................. 12
2.8 Iron (Fe)............................................................................................................................... 12
2.9 Chromium (Cr) .................................................................................................................... 13
2.10 Potassium (K) .................................................................................................................... 13
2.11 Sodium (Na) ...................................................................................................................... 13
2.12 Arsenic (As) ...................................................................................................................... 14
2.13 Lead (Pb) ........................................................................................................................... 14
2.14 Cadmium (Cd) ................................................................................................................... 14
2.15 Nickel (Ni)......................................................................................................................... 15
2.16 Instrumentation.................................................................................................................. 15
2.17 Theory of Atomic Absorption ........................................................................................... 16
2.18 Flame Atomic Absorption Spectrophotometry ................................................................. 17
2.19 Inductively Coupled Plasma Spectroscopy ....................................................................... 18
2.20 Limitations of FAAS and ICP ........................................................................................... 19
2.21 Microwave Assisted Digestion .......................................................................................... 19
CHAPTER 3 Methodology ........................................................................................................... 21
3.1 Instruments .......................................................................................................................... 21
ix
3.2 Reagents .............................................................................................................................. 21
3.3 Sample Collection ............................................................................................................... 21
3.4 Sample Cleaning ................................................................................................................. 22
3.5 Sample Digestion ................................................................................................................ 22
3.6 Digested Sample Filtration .................................................................................................. 22
3.7 Element Calibration Standards Preparation and Calibration curve ..................................... 23
3.8 Determination of Trace Element Concentration in Human Scalp Hair .............................. 23
CHAPTER 4 Results and Discussion ........................................................................................... 24
4.1 Standard Calibration Curves ............................................................................................... 24
4.1.1 Arsenic ( As) calibration curves ................................................................................... 24
4.1.2 Calcium (Ca) calibration curve..................................................................................... 24
4.1.3 Cadmium (Cd) calibration standards ............................................................................ 25
4.1.4 Chromium (Cr) calibration curve ................................................................................. 26
4.1.5 Copper (Cu) calibration curve ...................................................................................... 27
4.1.6 Potassium (K) calibration curve ................................................................................... 27
4.1.7 Magnesium (Mg) calibration curve .............................................................................. 28
4.1.8 Sodium (Na) calibration curve ..................................................................................... 29
4.1.9 Nickel (Ni) calibration curve ........................................................................................ 29
4.1.10 Lead (Pb ) calibration curve ....................................................................................... 30
4.1.11 Selenium (Se ) calibration curve ................................................................................ 31
x
4.1.12 Zinc (Zn) calibration curve ......................................................................................... 31
4.2 Limit of Detection (LOD) and Limit of Quantification (LOQ) .......................................... 32
4.3 Overall Trace Element Concentrations in all Human Scalp Hair Samples ......................... 33
4.4 Influence of Gender on Trace Element Concentration in Human Hair Scalp. .................... 34
4.5 Influence of Race on Trace Element Concentrations in Human Hair Scalp ....................... 35
4.6 Influence of Age on Trace Element Concentrations in Human Scalp Hair ........................ 38
4.7 Influence of Smoking Habits on Trace Element Concentrations in Human Hair Scalp. .... 41
4.8 Influence of Occupation on Trace Element Concentrations in Human Scalp Hair. ........... 43
4.9 Quality Control and Recovery Studies ................................................................................ 49
4.10 Determination of Element Ratio for Possible Diseases Markers ...................................... 49
4.11 Calcium and Magnesium Ratios ....................................................................................... 50
4.12 Zinc and Copper Ratio ...................................................................................................... 50
4.13 Calcium and Zinc Ratio..................................................................................................... 51
4.14 Sodium and Potassium ...................................................................................................... 52
4.15 Zinc and Iron Ratio ........................................................................................................... 52
4.16 Iron and Copper Ratio ....................................................................................................... 53
4.17 Evaluation of Significant Difference in Determined Trace Element Concentration......... 54
4.17.1 Evaluation of student t-test based on gender .............................................................. 54
4.17.2 Evaluation of student t-test based on race .................................................................. 55
4.17.3 Evaluation of student t-test based on smoker status ................................................... 57
xi
4.18 Overall Inter Element Associations in Human Scalp Hair ................................................ 58
4.19 Inter-Element Association between Males and Females ................................................... 59
4.20 Inter Elemental Association in Race ................................................................................. 60
4.21 Inter Elemental Association in Smokers and Non Smokers.............................................. 61
CHAPTER 5 Conclusion .............................................................................................................. 63
References ..................................................................................................................................... 64
xii
List of Figures
Figure 1. Development and growth cycle of human scalp hair.7 .................................................... 5
Figure 2. Schematic diagram of FAAS.55 ..................................................................................... 18
Figure 3. Schematic representation of ICP-OES.57....................................................................... 19
Figure 4. Calibration curve of As standards. ................................................................................ 24
Figure 5. Calibration curve of Ca standards. ................................................................................ 25
Figure 6. Calibration curve of Cd standards. ................................................................................ 26
Figure 7. Calibration curve of Cr standards. ................................................................................. 26
Figure 8. Calibration curve of Cu standards. ................................................................................ 27
Figure 9. Calibration curve of K standards ................................................................................... 28
Figure 10. Calibration curve of Mg Standards.............................................................................. 28
Figure 11. Calibration curve of Na standards. .............................................................................. 29
Figure 12. Calibration curve of Ni standards. ............................................................................... 30
Figure 13. Calibration curve of Pb Standards. .............................................................................. 30
Figure 14. Calibration curve of Se standards. ............................................................................... 31
Figure 15.Calibration curve of Zn standards. ............................................................................... 32
xiii
List of Tables
Table 1. LOD, LOQ of Trace Element Analysis .......................................................................... 32
Table 2. Overall Trace Element Concentrations (µg/g) in all Human Scalp Hair Samples (n=194)
....................................................................................................................................................... 34
Table 3. Influence of Gender on Trace Element Concentrations (µg/g) in Human Scalp Hair .... 35
Table 4. Influence of Race on Trace Element Concentration (µg/g) in Human Scalp Hair ......... 37
Table 5. Influence of Race Trace Element Concentration (µg/g) in Human Scalp Hair .............. 38
Table 6. Influence of Age (18-24) on Trace Element Concentrations (µg/g) in Human Scalp Hair
....................................................................................................................................................... 39
Table 7. Influence of Age (25-44) on Trace Element Concentrations (µg/g) in Human Scalp Hair
....................................................................................................................................................... 40
Table 8. Influence of Age (45-65) on Trace Element Concentrations (µg/g) in Human Scalp Hair
....................................................................................................................................................... 40
Table 9. Influence of Age (65+) on Trace Element Concentrations (µg/g) in Human Hair Scalp 41
Table 10. Influence of Smoking Habits on Trace Element Concentrations (µg/g) in Human Scalp
Hair ............................................................................................................................................... 42
Table 11. Influence of Smoking Habits on Trace Element Concentrations (µg/g) in Human Scalp
Hair ............................................................................................................................................... 43
Table 12. Influence of Occupation on Trace Element Concentrations (µg/g) in Human Scalp Hair
....................................................................................................................................................... 45
Table 13. Influence of Occupation on Trace Element Concentrations (µg/g) in Human Hair Scalp
....................................................................................................................................................... 46
xiv
Table 14. Influence of Occupation on Trace Element Concentrations (µg/) In Human Scalp Hair
....................................................................................................................................................... 47
Table 15. Influence of Occupation on Trace Element Concentrations (µg/g) In Human Scalp
Hair. .............................................................................................................................................. 48
Table 16. Percentages of Recovery Studies .................................................................................. 49
Table 17. Average Ca/Mg, Zn/Cu, Ca/Zn, Mg/Zn, Na/K, Zn/Fe Ratios in Human Scalp Hairs by
Category ........................................................................................................................................ 53
Table 18. Evaluation of Differences in Trace Element Concentrations in Men and Women Using
Student T-test (Women, N =108, Men, N=86) ............................................................................. 55
Table 19. Evaluation of Differences in Trace Element Concentration in Race Using Student Ttest (African American, N =80, Caucasian, N=85)....................................................................... 57
Table 20. Evaluation of Differences in Trace Element Concentration in Smokers and NonSmokers Using Student T-test (Smokers, N =16, Nonsmoker, N=133) ....................................... 58
Table 21. Overall Inter-Element Association in Human Scalp Hair ............................................ 59
Table 22. Inter-Elemental Association in Male and Female........................................................ 60
Table 23. Inter-Elemental Association in African American (AA) and Caucasian (CC) ............. 61
Table 24. Inter-Element Association in Smokers (SM) and Non-Smoker (NS).......................... 62
xv
NOMENCLATURE
As
Arsenic
Cd
Cadmium
Ca
Calcium
Cr
Chromium
Cu
Copper
K
Potassium
Mg
Magnesium
Na
Sodium
Ni
Nickel
Pb
Lead
Se
Selenium
Zn
Zinc
Fe
Iron
FAAS
Flame Atomic Absorption Spectrophotometry
ICP
Inductively Coupled Plasma
1
Abstract
Essential elements play important roles in physiological functioning of the human body,
however potentially toxic elements are non-essential and their presence in the human body has
several health implications. Elevated concentration of heavy metals results, hypertension,
depression, low intelligence quotient in children and cancer diseases. Heavy metal poisoning can
be detected in humans by measuring the concentrations of potentially toxic elements in blood,
saliva, urine, or other tissues. Human scalp hair (HSH), however, is a simpler, less invasive
sample in which the elements are more concentrated and reside longer. In this study, HSH
samples were collected and used to assess human exposure to potentially toxic elements (PTEs)
and essential elements (EEs) in the state of North Carolina, USA using accelerated microwave
assisted acid digestion and inductively coupled plasma optical emission spectroscopy (ICPOES). The figures-of-merit of the ICP-OES were appropriate for elemental analysis in HSH
with detection limits as low as 0.0001 mg/L for Cd, good linearity (R2 > 0.9978), and percent
recoveries that ranged from 96 106% for laboratory fortified blanks. The concentrations of EEs
in HSH were larger than those of PTEs, with Ca having the highest average concentration (3,080
µg/g, s =14,500, n =194). Some of the maximum concentrations observed for As (65 µg/g), Ni
(331 µg/g), Cd (2.96 µg/g), and Cr (84.6 µg/g), in individual samples were concerning. Samples
were statistically analyzed to determine the influence of race, gender, smoking habits, or age on
the elemental concentrations in HSH. Higher concentrations of EEs were observed in the scalp
hair of Caucasians, females, and non-smokers and the differences were often significant at a 90%
confidence level. Several pairs of EEs, for example Ca-K, Ca-Mg, and Ca-Zn, were strongly
correlated in Caucasian hair but uncorrelated in African American hair. Similarly, EEs were
strongly correlated in female hair but weakly correlated in male hair. PTE pairs (As-Cd, As-Se,
2
Pb-As, and Se-Cd) were strongly correlated in the hair of smokers but uncorrelated in that of
non-smokers, suggesting that cigarette smoke is a common source of PTEs in humans.
3
CHAPTER 1
Introduction
1.1 Background
The first analytical determination and forensic analysis of human hair was by Rudolf
Virchow a Professor and prosecutor of the Dead house of Berlin Charite hospital.1,2 Interestingly,
he determined arsenic in the hair of a body exhumed after eleven years. In the early nineteenth
century, Goldblum determined amphetamine in the hair of a guinea pig. Baumgartner.3,1 also
extracted opiates with methanol by heating for 2 hours and evaporating and reconstituting in a
buffer then followed by examination with Abuscreen radioimmunoassay ( RIA). After this study
the genesis of hair analysis was justified even though there were few condemnations. In 1980,
Klug fulfilled the conditions of environmental toxicology for hair analysis by confirming
radioimmunological results by chromatographic techniques.4 He disintegrated his hair samples
with NaOH and then hydrolysed it with concentrated hydrochloric acid and then extracted
morphine and codeine. Quantification was carried out after performing thin layer
chromatography using flourescence detector. In forensic analysis, the most important
characteristic of hair is its morphology, color and cosmetic products being used. The human hair
is a simple structure composed of keratin that grows from the dermis of the skin. The human
hair has potential to divulge information on the nutritional status and exposure of subjects to
essential trace elements and potentially toxic element s concentration. The aims of this research
are categorized into four main themes. All these themes are very essential in environmental
biomonitoring and most importantly in the development of possible biomarkers for possible
disease diagnostics.
4
1.2 Aim
The overall aim of the study is to utilize human hair scalp as biological specimens for
bioanalytical study.
1.3 Specific Aims
To determine the concentration of essential and potentially toxic elements in human
scalp hair.
To evaluate the influence of gender, race, age, smoking habit, and occupations on the
levels of elements detected in human hair scalp samples.
To determine inter-element association of elements in human scalp hair samples.
To determine and use the ratios of element in human scalp hair for possible disease
markers for biomedical study.
1.4 Justification
Trace elements play a vital role in the human system but excessive amount tend to
become very dangerous to human health. On the other hand, potentially toxic elements are
ubiquitous and their presence in our environment, food and drinking water pose a lot of
environmental and health hazard, thus there is the need to the know levels and how these
elements bioaccumulate in the biological system of human being. Essential and potentially toxic
elements originate from various sources; therefore there is the need to know how the
distributions of these trace elements are affected by gender, race, smoking habits, and occupation
of humans. This knowledge would be useful in forensic study, biomedical diagnostics of certain
diseases and also provide information about possible environmental exposure to potentially toxic
elements.
5
1.5 Biology of the Human Scalp Hair
Hair is protein rich complex structure. It grows from the dermis of the skin. It is
composed of keratin; a complex mixture of helical proteins which is produced in special
epithelial cells.5 There are 3 different types of layers that are usually present in the cross section
of the human hair. The outermost layer of the hair which is called the cuticle is composed of a
protective coating for the hair fiber. The second layer is called cortex, which is composed of
-keratin mass. Medulla is the third layer and is
composed of cells that form shaft through the middle of the hair. There are 3 different growth
stages in the mammalian hair.6 The first stage is the anagen stage; this is the active growth phase
of the hair follicle. Catagen is the second growth phase and this is the transition period between
growth and rest. Hair in this stage continues to grow but at a decreasing rate. The rest period for
hair growth is called telogen. Hair present is shed and no growth takes place. Figure 1 shows a
pictorial description of the growth phase in human scalp hair.
Figure 1. Development and growth cycle of human scalp hair.7
6
1.6 Hair Analysis
Analysis involving hair is of great interest in many fields of research and this interest
stem from the fact that the biogenic composition of hair is not influenced by environmental
conditions and contaminations. However, the mechanism of how substances such as trace
elements and controlled substances are incorporated into the hair matrix is yet to be fully
understood.
1.7 Biomonitoring of Environmental Elements and Chemicals of Concern
Biological monitoring has become the most common application for trace element
determination in human tissues. Biomonitoring is defined as a method of assessing human
exposure to chemicals by measuring the chemicals or their metabolites in human specimen.8 It is
employed to identify the relationship between chemical exposure and disease development or
abnormalities. It is also employed to find relationships between chemical body burden and eating
habits or workplace exposure.
1.8 Use of Human Scalp Hairs as a Biomonitor and Biomakers
Scalp hair is human hair, with its roots originating from the scalp of human head. Scalp
hair has a potential of being used as an excellent biomonitor due to its periodic intake of toxins
or other analytes of interest over long periods of time.9 The uniqueness of the human scalp hair
structure enables it to be utilized for the investigation of exposure to toxins or heavy metals.10
1.9 Importance of Hair Analysis
The advantages of using human hair for trace element determination are i) it is less
invasive and avoids vein puncture, ii) it is biologically stable and can be stored for a long period
of time, and iii) it is able to bioaccumulate trace elements of an extended period of time9. A
common application for trace element determination in human specimen is biomonitoring. As a
7
biological matrix, human scalp hairs can also bioaccumulate controlled substances for a long
period of time.
8
CHAPTER 2
Literature Review
2.1 Trace Elements
Trace elements also known as micronutrient in chemical biology and are elements
required by living organisms in minute amount usually less than 0.01 percent by volume.11 Trace
elements are very important for the human body to maintain normal but yet complex
.12 The daily
requirement of dietary trace elements is in few milligrams per gram.13 Trace elements are usually
grouped into two categories; namely essential trace elements, and ultra-trace elements.
Every living life depends on the availability of food and water for sustenance.
Availability of food and water is directly correlated to the presence of many essential trace
elements.14 Dietary essential trace elements sustain life of living organisms. Trace elements are
not made by the body, thus their ultimate source is through dietary intake. Trace
elements cannot be synthesized like the way organic micronutrients such as vitamins are
synthesized. Currently 26 out of the 90 natural occurring elements are known to be essential for
human life. Of these 26 elements, 11 are considered major elements and 15 are considered as
non-essential trace element. The list of trace element is as follows; iron, zinc, copper,
manganese, nickel, cobalt, molybdenum, chromium, selenium, iodine, fluorine, tin, silicon,
vanadium and arsenic. Interestingly, nature has selected trace elements that are essential for
human well-being. An element is considered essential if deficiency results in consistent
impairment of function from optimal to suboptimal.15 Conditions for an element to be classified
as essential trace element are as follows.16
i. presence in all living tissues.
9
ii. concentration from one animal to another is fairly constant.
iii. absence in an organism induces physiological and structural abnormalities.
iv. addition of these element prevents or reverses physiological and structural abnormalities
caused in their absence.
v. abnormalities induced by deficiency are accompanied by significant biochemical changes
Trace elements that fail to meet these criteria occur in variable concentrations in living
tissues. They are known as non-essential trace elements and are acquired as a result of
environmental contamination. They can also be classified as toxic elements because their
biological importance is limited to their toxicity. Examples of such elements are rubidium,
germanium, cadmium, aluminum, titanium, zirconium, mercury, lead arsenic and gold are among
a few.
2.2 Sources of Trace Elements and Tolerable Amounts in Humans
Most trace elements are of geological origin but they bio accumulate in plants which
serve as food for humans. Some other sources are aquatic environments and the atmosphere. The
average daily intakes of trace elements in humans are variable. The minimum amount of trace
element required by humans is expressed in proportion of dry food consumed. This amount is
arrived at by considering the health, growth, and fertility of the organism.
2.3 Selenium (Se)
Selenium speciation in plant and animal sources requires understanding of the
biosynthetic pathways involved in Se assimilation by plants and how these are metabolized in
animals. Major species present in plants are the selenate (SeO42-).17 There is little information on
the type of Se species present in diet of animal origin. Some food sources of Se are grains, nuts,
tuna and turkey are among a few. Selenium is of great importance to the human body. As a major
10
constituent of selenoproteins, Se has both enzymatic and structural functions. It is also known as
an antioxidant and a catalyst for the production of active thyroid hormone. Selenium is required
for the proper function of the immune system and it plays a key role in counteracting the
development of virulence and inhibiting the progression of HIV to AIDS. It is important in
sperm production in males. Deficiency of selenium has been associated with conditions
involving oxidative stress, and cardiovascular diseases. High levels of selenium intake may be
linked with reduced risks of cancers. Clinical analysis are being undertaken to confirm or refute
this claim.18 Concentrations above 390 effects in humans.19
2.4 Calcium (Ca)
Calcium accounts for 1-2% of the total adult human body weight. Ca is stored in bones
and teeth. It is usually stored as calcium phosphate. Dietary calcium plays a crucial role in bone
metabolism and bone health. Sources of calcium include dairy products, legumes and leafy
vegetables such as collard greens. There is a considerable evidence that increased calcium intake
have benefits for bone development and reduced risk of osteoporosis.20
Calcium deficiency results in low intestinal absorption of other essential elements like
magnesium (Mg). It also results in reduced bone mass and osteoporosis. Low calcium intake in
combination with vitamin D often cluster with higher prevalence rates of obesity. There have
been much interest in the mechanism by which calcium and vitamin D could regulate body
weight and adiposity.21 Calcium also helps regulate normal heartbeat, help in the expansion and
contraction of muscles and also aids in blood clotting.22 Through the aid of calcium regulating
hormone, calcium receptors and other mechanism, calcium helps reduce the risk of hypertension,
colon cancer, breast cancer and kidney stones.23
11
2.5 Copper (Cu)
Copper is an essential trace element and very important in the proper functioning of many
cellular enzymes. Copper ion undergoes redox oxidation to exist as Cu2+ or Cu+ in most
enzymatic reactions. This property allows Cu to play a pivotal role in cell physiology as catalytic
cofactor in the redox chemistry of enzymes. It is also important in mitochondria respiration, iron
absorption and free radical scavenging in the human body.24The average intake of Cu in adults
ranges from 0.6 to 1.6 mg/d. Sources of copper are seeds, grains, nuts, beans and shell fish.
Copper plays physiological roles such as fetal development, infant development and growth,
brain development and function. It also aids in glucose and cholesterol metabolism, formation of
skin pigments, myocardial contractility and the maintenance of the human skin and hair.25
2.5.1 Toxicity of copper
Generally, copper is considered as an essential element in human nutrition. However, Cu
concentrations or exposure may result in adverse health effects.26 Toxicity of copper also leads to
Wilson disease, a disease which arises as a result of poor incorporation of copper to
ceruloplasmin and impaired copper excretion and this mutation causes copper toxicosis due to
copper accumulation.25 The recommended daily intake should not exceed 10mg/day.27
2.6 Zinc (Zn)
In nutrition, zinc is very essential to microorganisms, plants and animals.28 Zinc is found
to be a vital component of several metalloenzymes, including carbonic anhydrase, alkaline
phosphatase, lactic dehydrogenese and carboxypeptidase.29 In metabolism, zinc is required in the
synthesis of nucleic acid and protein. It is present in a large number of proteins, thus giving the
proteins their structural functions. It also aids in catalysis in the human body.30Zinc also forms
part of the physiological oxidative defense system. Zinc is also essential in maintenance of the
12
normal structure of the cytoskeleton and also plays an essential role in cellular signaling.31 Zinc
deficiency is related to several genetic conditions,
, and
celiac sprue.32
2.7 Magnesium (Mg)
It is the second most abundant trace element in most cellular systems and is basically
involved in all metabolic pathways. Magnesium is usually found in cereals and vegetables.
About 1% of the body magnesium is found in the blood plasma. Magnesium serves as an
essential cofactor in all enzymatic systems involved in DNA processing.
in
DNA processing include nucleotide excision repair, base excision repair and removal of DNA
damage generated by environmental mutagens33. Magnesium plays a role in blood pressure
regulations by modulating vascular tone and activity. It acts as calcium channel antagonist.
Magnesium also aids in glucose and insulin homeostasis. Magnesium serves as a therapeutic
agent in the management of hypertension.34
2.8 Iron (Fe)
Iron is one major essential element in humans and both iron deficiency and
excessiveness
results in deviation from normal health condition.35 Iron is an important
component of hemoglobin, myoglobin and various enzymes.35 Stored forms of iron amount to
.36
As a transition metal and a pro-oxidant, iron
catalyses several cellular reactions that results in production of reactive oxygen species. Iron
forms part of ferroportin which serves as a transporter and plays an important role in intestinal
absorption and cellular iron release
37
. Dietary iron sources include fortified cereal product,
certain vegetables, red meat, poultry and fish.
13
2.9 Chromium (Cr)
Chromium is an essential nutrient required for sugar and fat metabolism. Insufficient
intake of chromium results in symptoms similar to diabetes and cardiovascular diseases.38 Cr3+
has a very large safety range and there has been no documented evidence about chromium
toxicity in any nutritional studies up to levels of 1mg per day.38 Chromium has shown to improve
lean body mass in humans. Sources of chromium include breads, cereals, fish, meats and some
vegetables.39Chromium supplement helps improve glucose and insulin regulation. Chromium
deficiency results in impaired glucose intolerance, low respiratory quotient.40 Cr6+ and its
compounds are very toxic and a have adverse effect on humans. Exposure to Cr
6+
is linked to
increased level of respiratory cancers.41
2.10 Potassium (K)
Potassium is a macro nutrient; strong evidence indicates that potassium lowers blood
pressure whether consumed in foods primarily or potassium bicarbonate or in dietary
supplements as potassium salts.42 Potassium has been reported to reduce both systolic and
diastolic blood pressure in people with normal and high blood pressure.43 Eating potassium rich
foods reduce or prevent the blood pressure response to dietary sodium. Sources of potassium rich
foods are potatoes, carrot, soybean, banana and plain yoghurt.
2.11 Sodium (Na)
Sodium is an alkali group metal which usually exists as salts. The common form of
sodium salt is sodium chloride (NaCl). Sodium is an essential trace element. It plays important
roles in regulating extracellular fluids and active transport of substances across the cell
membrane.44 Sources of sodium include table salt, milk, celery and food additives such as baking
soda, soy sauce, and garlic salt.
14
2.12 Arsenic (As)
One major environmental and biological toxicant is arsenic. Humans may be exposed to
this toxicant from water obtained from arsenic ground rich strata, industries, and agrochemicals
which finally end up in the food chain of humans. Other sources of exposure are through direct
inhalation and dermal exposure. First case of chronic arsenic poisoning from contaminated
waters was reported in Taiwan in 1961 by Tseng et al.45 Inorganic arsenic forms such as arsenite
and arsenate exhibit a great form of toxicity to living organisms including humans.46 Arsenic is a
protoplastic poison because it has effects on sulphydryl groups of cells leading to interferences
with cells, enzymes, cell respiration, and mitosis.47 Concentration above 0.39 carcinogenic effects in humans.
2.13 Lead (Pb)
Lead is another toxic element which has caused various environmental problems in
different parts of the world. Sources of lead included, gasoline, storage batteries, toys and
faucets. In the US alone, about 200,000 tons of lead pear year is released from the exhaust of
vehicles which then bioaccumulate in plants which also serve as food for humans.48
Concentrations above 400 .19
2.14 Cadmium (Cd)
Another toxic trace element is cadmium. Cadmium primarily occurs in ores with lead,
copper and zinc. Till date, there has not been any evidence of any physiological function of
cadmium. Cadmium is a major toxicant that can lead to kidney, bone and pulmonary damages.49
Industrially, cadmium is used in the manufacture of anticorrosive agent, color pigment and
manufacture of nickel-cadmium batteries. Cadmium pollution is largely caused by incineration
and dumping of cadmium waste.50 Cigarette smoking also contribute a major source of cadmium
15
in the human system.50 Cd is also present in foodstuffs in variable concentration. Concentrations
exceeding 37 se health effects in humans.
2.15 Nickel (Ni)
It is a naturally occurring metallic element in crust. Human exposure to Ni occurs
through inhalation.51 No known physiological importance of nickel exists. Nickel compounds are
found in the soil in the form of sulfides and silicates. Chronic exposure can lead to lung fibrosis,
cardiovascular and kidney diseases.51 In industries nickel is used in electroplating,
electroforming and production of nickel-cadmium batteries. It is also used to cast coins and
jewellery. 1,600 s the maximum level that the human body can take. Concentration above
this level cause adverse effects in human.19
2.16 Instrumentation
In 1814, Fraunhoffer observed atomic transitions of solar radiation as absorbance lines52.
Kirchoff and Bunsen also undertook atomic emission experiments which lead to the discovery of
two new elements. Cesium and rubidium were discovered through their experiment.53 In the
early nineteen century, Bohr initiated the idea of quantum explanation of discrete spectra
observed in atomic spectroscopy. Atomic physicist and spectroscopists have used this basis as a
foundation to understand selection rules, energy levels and allowed atomic and electronic
transitions. Atomic spectroscopy became very common in the early nineteenth century and
utilized in metallurgical and mineralogical industries. In recent years modern analytical
spectroscopy is divided into three categories, namely i) atomic absorption, ii) atomic
fluorescence, and iii) atomic emission.
Atomic absorption spectroscopy is an analytical technique where high intensity narrow
bandwith sources provide photons which are absorbed by atoms in the analyte. In 1955, Walsh
16
published the basic concepts of atomic absorption spectroscopy. Alan Walsh designed the atomic
absorption spectrometer which as has its flames serving as a source of radiation and atomizer.54
Modern day use of atomic absorption spectrometer is for both quantitative and qualitative
analysis. The basic instrumentation for atomic absorption spectrometer (AAS) is a light source,
an atomizer, a wavelength isolator, and a detector.
2.17 Theory of Atomic Absorption
Absorption of radiation by atoms of the analyte is governed by two laws; the first law
which is the Lamberts law states that the radiation absorbed in a transparent cell is independent
of the incident radiation. Beers law which is the second law states that absorption of radiation
energy is exponentially proportional to the number of absorbing species present in the absorption
path length. Combination of both laws gives the fundamental Beer-Lambert law which provides
sound basis of atomic absorption. When monochromatic radiation is incident on absorption cell,
some energy is absorbed by atoms of the analyte and the rest is transmitted. Mathematically, this
can be represented in equation 1.
T = Itr/Io
Equation 1
Alternatively absorbance is given by the relation in equation 2
A=log (IO/Itr) 2
Absorbance can also be mathematically written as
A= abc 3
where Io, Itr, a, b, c and T are incident radiation, transmitted radiation, absorption coefficient,
path length, concentration and Transmittance respectively.
17
2.18 Flame Atomic Absorption Spectrophotometry
Flame atomic absorption spectrometer (FAAS) was developed in the 1950s. It is a
common method used for quantifying many elements. The FAAS is composed of a fuel
(acetylene), oxidizer, hallow cathode lamp (HCL), nebulizer, burner head, flame and a detector.
In FAAS, fuel gas and the oxidant gas are mixed to provide fuel mixture for the production of
flame. Liquid samples are aspirated by the aid of the nebulizer. Samples are atomized in the
flame. The flame is aligned to a light source generated by the hallow-cathode-lamp (HCL) of
appropriate wavelength. The flame causes atoms to undergo electronic transition from the
ground state to excited states. When atoms present in the sample undergo electronic excitations
and then absorbs the incident radiation from the HCL. The more concentrated the solution, the
more light is absorbed. Each HCL generates light which is specific for each element. Light
passing through the flame is received by the monochromator which accepts and transmits light at
specific wavelength into the detector. The detector measures the intensity of light, thus when
some of the incident radiation is absorbed by atoms of the analyte, the radiation intensity is
reduced. The detector then records the reduction in intensity as absorption. A calibration curve is
constructed by plotting aborbance of light and concentration known standards of analyte of
interest. Concentration of analytes can now be determined by extrapolating the absorbance of the
analyte on the calibration curve.
18
Figure 2. Schematic diagram of FAAS.55
2.19 Inductively Coupled Plasma Spectroscopy
Inductively coupled plasma optical emission spectroscopy (ICP-OES) is one of the most
sensitive, selective and accurate technique used for trace elements analysis. Its operational
principle is based on spontaneous emission of photons from atoms or ions that have been excited
in a radio- frequency discharge. Samples to be analyzed are converted into liquid form by
extraction or acid digestion. Liquid samples are converted to aerosols and channeled through the
plasma. The core temperature of the plasma approximates to 10,000K. Due to these high
temperatures, aerosols are evaporated rapidly. Analytes are then obtained as free atoms in
gaseous state. Energy from the plasma causes effective collisions and excites atoms of the
analyte. Atoms in the excited states emit photons which is a characteristic of each element of
interest. The number of photons emitted is directly proportional to the concentration of the
analyte.56
19
Figure 3. Schematic representation of ICP-OES.57
2.20 Limitations of FAAS and ICP
The chemical form of analyzed element is not detected. Example whether Fe2+ or Fe3+.
Not all elements can be detected by FAAS and cannot also detect below certain concentration
range. However ICP is more sensitive than FAAS. Both ICP and flame AAS are destructive
technique thus requires sample degradation.
2.21 Microwave Assisted Digestion
Microwaves provide the most efficient way for wet acid digestion procedures. This is
because heating is internal and takes place in the digestion mixture. This makes the use of
20
microwave assisted digestion more efficient than the conventional heating process.58 Nitric acid
(HNO3) is the most common oxidizing agent often used to digest organic samples because all
metal nitrate formed are soluble. An example is represented by the equation below.
Pb2++ HNO3
Pb(NO3)2 + H2
4
21
CHAPTER 3
Methodology
3.1 Instruments
Mars X Microwave (CEM USA)
Oven (Fisher Scientific Isotemp 600 series)
ICP-OES (Varian 710 ES axial)
Flame AA spectrometer (Thermo Scientific ICE 3000 series)
3.2 Reagents
Trace metal grade HNO3 (Fisher Scientific 99.999% purity).
Triply deionized water (Thermo Scientific GenPure UV-TOC/UF, Hungary).
Methanol (Fisher Scientific)
Acetone (Fisher Scientific).
Multi-element stock standard; As, Cd, Cr, Cu, Ni, Pb, Se and Zn (SCP Science, Baie- Canada).
Multi-element stock standard; Ca, K, Mg and N (Environmental Express, Charleston SC, USA)
Yttrium internal standard (SCP Science, Baie- ).
3.3 Sample Collection
Clean Ziploc bags were soaked in diluted nitric acid, the Ziploc bags were air dried and
stored in a clean box. Hair samples for analysis were collected from participants who previously
filled questionnaire. Questionnaires were prepared to collect information on gender, age, race,
occupation and smoking habits of the participants. Hair samples were collected with a stainless
steel clipper or scissors at selected barber shops and saloons in Greensboro and Durham area of
22
North Carolina. Hair samples were collected near the scalp of 194 participants. The samples
were stored in a cleaned Ziploc bag and transported to the lab and stored at 25°C.
3.4 Sample Cleaning
Hair samples were divided into two portions. The first portion of hair was washed using
10 ml of acetone in an eppendorf tube followed by a second wash using 10ml of methanol.
Sequential washing with acetone and methanol for a minimum of three times was done to
remove any exogenous contaminants. Washed hair samples were rinsed thoroughly with
deionised water (Thermo Scientific, GenPure UV-TOC/UF, Hungary). Hair samples were oven
dried at 55°C using Fischer Scientific Isotemp oven for four hours to evaporate all organic
solvents used in the washing process. The dried hair samples were stored in a clean Ziploc bag
and stored in a dust free bucket.
3.5 Sample Digestion
About 0.5 g of each washed and dried hair sample was weighed using Ohaus Analytical
Plus balance into a Teflon microwave vessel. Approximately, 10ml of HNO3 was added to each
vessel and allowed to predigest in a fume hood for 45 minutes. The predigested hair samples in
the vessel were capped and locked in their respective chambers. The Teflon vessels in their
respective chambers were placed in CEM Marsx microwave digester which was operated at
200W, 200 psi pressure, 200°C temperature for 35 minutes and ramped for 10 minutes.
3.6 Digested Sample Filtration
The digested hair samples were filtered using Fisherbrand filter paper with diameter of
8.0 cm with a medium porosity and a slow flow rate. The filtrate collected was diluted to the
mark in a 25mL volumetric. The diluted solutions were transferred into glass vials and stored in
a clean cabinet.
23
3.7 Element Calibration Standards Preparation and Calibration curve
Calibration standards were prepared from two multi-element stock solutions containing
Na (Environmental Express) ! "" Y (SCP
Science). Calibration standards contained 0.01- . Calibration standards were analyzed and their emission intensities
recorded. Calibration curves were constructed for each element by plotting emission intensities
of the respective elements against the concentrations of the calibration standards.
3.8 Determination of Trace Element Concentration in Human Scalp Hair
Analysis of trace elements were carried out simultaneously using inductively coupled
plasma optical emission spectrophotometer with CCD detector. The digested samples were
analyzed in triplicates under the following conditions, the plasma power 1.2 kW, the argon
flowrate was15.0 L/min the read time was 60 seconds, and nebulizer pressure was 250 kPa. The
wavelength use are as follows As; 370.602 Ca; 214.439 Cd; 267.716 Cr; 327.395 Cu; 766.491 K;
279.553 Mg; 568.821 Na; 231.604 Ni; 220.353 Pb;196.026 Se;371.029 Y(internal standard);
213.857 Zn. Fe concentrations were determined using Thermo Scientific ICE 3000 series flame
AA spectrometer using pre-mixed burner air-acetylene flame. Absorption was at 248 nm.
Calibration curves were constructed for each element by absorption or emission intensity versus
concentration. Trace element concentrations were determined using the formula below.
## $ g mL-1 in digested hair sample
weight of hair sample (g)
x the volume (mL) of solution
24
CHAPTER 4
Results and Discussion
4.1 Standard Calibration Curves
Calibration standards are prepared by plotting emission intensity versus concentration of
standards. This serves as module to determine concentration of the analyte of interest.
4.1.1 Arsenic ( As) calibration curves
Figure 4 show As calibration curve. This plot is obtained by plotting As standard
concentration (1.0- The equation obtained for the
calibration curve; y = 182.45x + 1.8986 and an R2 value of 0.9999. This value indicates a very
high linearity between emission intensity and As calibration standards.
As calibration curve
Intensity (a u)
1000
800
y = 182.45x + 1.8986
R² = 0.9999
600
400
200
0
0.0
2.0
4.0
Concentration (g/mL)
6.0
Figure 4. Calibration curve of As standards.
4.1.2 Calcium (Ca) calibration curve
The calibration curve for Ca is determined by plotting emission intensity against different
concentrations of Ca standard (20-120 ). The degree of linearity between emission
25
intensity and concentration of standards was determined to be 0.9996 which indicates accurate
preparation of standards. The equation for the curve was determined to be y = 1276.1x + 533.01.
Ca calibration curve
Intensity (a u)
160000
120000
y = 1276.1x + 533.01
R² = 0.9996
80000
40000
0
0.0
50.0
100.0
150.0
Concentration (g/mL)
Figure 5. Calibration curve of Ca standards.
4.1.3 Cadmium (Cd) calibration standards
A plot of emission intensity versus calibration standard of variable concentrations yielded
the calibration curve for Cd. The graph shows a direct linear relationship between emission
intensity and concentration of calibration standards. The correlation coefficient depicts the linear
dependence of the emission intensity and the concentrations of the calibration standards. The
correlation coefficient obtained was 1 indicating no degree of error during standard preparation.
Equation for the curve; y = 7778.5x + 64.327.
26
Cd calibration curve
y = 7778.5x + 64.327
R² = 1
Intensity (a u)
50000
40000
30000
20000
10000
0
0.0
2.0
4.0
Concentration (g/mL)
6.0
Figure 6. Calibration curve of Cd standards.
4.1.4 Chromium (Cr) calibration curve
A correlation coefficient of 0.9999 was obtained when emission intensity of radiation
was plotted against Cr calibration standards. This value indicates the linear relationship between
the two quantities. The equation for the curve was determined to be y = 14481x + 163.
Cr calibration curve
Intensity (a u)
80000
y = 14481x + 163
R² = 0.9999
60000
40000
20000
0
0.0
2.0
4.0
Concentration( g/mL)
Figure 7. Calibration curve of Cr standards.
6.0
27
4.1.5 Copper (Cu) calibration curve
Figure 8 shows Cu calibration curve. This plot is obtained by plotting As standard
concentration (1.0- calibration curve; y =11786x + 264.87 and a correlation coefficient (R2) of 0.9998. This value
indicates a very high and precise degree of linearity between emission intensity and Cu
calibration standards.
Intensity (a u)
Cu calibration curve
80000
60000
y = 11786x + 264.87
R² = 0.9998
40000
20000
0
0.0
2.0
4.0
Concentration (g/mL)
6.0
Figure 8. Calibration curve of Cu standards.
4.1.6 Potassium (K) calibration curve
A plot of emission intensity against calibration standards yielded the calibration curve
illustrated in figure 9. The correlation coefficient (R2) obtained for the curve was determined to
be 0.9978. The correlation coefficient is used to describe the linear relationship between the plot
of emission intensity and calibration standards. The equation for the curve was determined to be
y = 28064x - 443.75.
28
K calibration curve
Intensity (a u)
160000
y = 28064x - 434.75
R² = 0.9978
120000
80000
40000
0
0.0
2.0
4.0
Concentration (g/mL)
6.0
Figure 9. Calibration curve of K standards
4.1.7 Magnesium (Mg) calibration curve
A plot of emission intensity against calibration standards is represented in figure 9. A
correlation coefficient of 0.9975 was obtained. This depicts the linear relationship between the
calibration standards and the emission intensities. The equation determined for the calibration
curve for magnesium was y = 326922x-1775.9.
Mg calibration curve
Intensity (a u)
1800000
1200000
y = 326922x - 1775.9
R² = 0.9975
600000
0
0.0
2.0
4.0
Concentration ( g/mL)
Figure 10. Calibration curve of Mg Standards.
6.0
29
4.1.8 Sodium (Na) calibration curve
Concentration standards of Na were plotted against emission intensity. The calibration
curve obtained is represented in figure 11. The correlation coefficient R2 = 1, demonstrating the
linearity of the constructed calibration curve. The equation of the line was determined to be y =
163.69x + 68.217.
Intensity (a u)
Na calibration curve
24000
y = 163.69x + 68.217
R² = 1
16000
8000
0
0.0
50.0
100.0
150.0
Concentration (g/mL)
Figure 11. Calibration curve of Na standards.
4.1.9 Nickel (Ni) calibration curve
Calibration curve for Ni was constructed by plotting emission intensity on the y-axis
against concentration of standards on the x-axis. The correlation coefficient signifies the linear
dependence of the emission intensity and the concentration standards. The R2 value obtained for
the calibration curve was 0.9998. This value shows the linearity of the calibration curve. The
equation obtained for the curve was y= 2093.2x + 34.52.
30
Intensity ( a u)
Ni calibration curve
12000
8000
y = 2093.2x + 34.52
R² = 0.9998
4000
0
0.0
2.0
4.0
Concentration (g/mL)
6.0
Figure 12. Calibration curve of Ni standards.
4.1.10 Lead (Pb ) calibration curve
A plot of emission intensity against calibration standards yielded the calibration curve
illustrated in figure 13. The correlation coefficient (R2) obtained for the curve was determined to
Intensity (a u)
be 0.9998. The equation for the curve was determined to be y= 712x + 15.76.
Pb calibration curve
4000
y = 712x + 15.76
R² = 0.9998
3000
2000
1000
0
0.0
2.0
4.0
Concentration ( g/mL)
Figure 13. Calibration curve of Pb Standards.
6.0
31
4.1.11 Selenium (Se ) calibration curve
Figure 14 shows Se calibration curve. This plot is obtained by plotting Se standard
concentration (1.0- calibration curve; y=182.45x + 1.8986 and a correlation coefficient (R2) of 1. This value
indicates a very high and precise degree of linearity between emission intensity and Se
calibration standards.
Intensity (au)
Se calibration curve
800
y = 134.74x + 2.1204
R² = 1
600
400
200
0
0.0
2.0
4.0
6.0
Concentration (g/mL)
Figure 14. Calibration curve of Se standards.
4.1.12 Zinc (Zn) calibration curve
A plot of emission intensity versus calibration standard of variable concentrations yielded
the calibration curve for Zn. The graph shows a direct linear relationship between emission
intensity and concentration of calibration standards. The correlation coefficient obtained was 1.
Equation for the curve; y=7778.5x + 64.327.
32
Intensity (a u)
40000
30000
Zn calibration curve
y = 6803.8x + 84.516
R² = 1
20000
10000
0
0.0
2.0
4.0
6.0
Concentration (g/mL)
Figure 15.Calibration curve of Zn standards.
4.2 Limit of Detection (LOD) and Limit of Quantification (LOQ)
Results in Table 1 represents limits of detection and limits quantification parameters.
LOD and LOQ are calculated by using the equation
and
respectively where s represents the
standard deviation of the blank and m is the slope of the calibration curve.
Table 1.
LOD, LOQ of Trace Element Analysis
Element
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
0.04
0.07
0.0001
0.0006
0.02
0.02
0.006
0.4
0.001
0.002
0.006
0.01
12.8
0.011
0.217
0.0003
0.002
0.09
0.063
0.021
1.44
0.003
0.005
0.025
0.022
42.6
33
4.3 Overall Trace Element Concentrations in all Human Scalp Hair Samples
Trace element analysis of human scalp hair enabled the opportunity to have information
about the individuals dietary habits and possible exposure to toxic elements.10 After analyzing
194 human scalp hair samples, the overall trace element concentrations are given in Table 3. A
total of 13 trace elements were determined a Arsenic (As), Calcium (Ca), Cadmium (Cd), Chromium (Cr), Copper (Cu), Potassium (K),
Magnesium (Mg), Sodium (Na), Nickel (Ni), Lead (Pb), Selenium (Se), Zinc (Zn) and Iron (Fe).
The average trace el !" # " $ % $
& "! ' ! ' " ( ! ) " * + $ ,- High concentrations of Ca from
subjects are likely due to from high deposition of Ca in tissues.20 The human scalp hair is a
protein rich tissue, and therefore has a high tendency to accumulate the excess calcium. K, Na,
Mg, Zn, and Fe are high because they are essential and are usually obtained from dietary sources.
Sodium plays a key role in regulating the human body blood pressure. Muscles and nerves also
require sodium to function properly. These groups of elements are classified as macro elements
because they are required in large quantities to perform their respective functions. The
concentration ranges for the overall trace elements are found in Table 2 The wide range for
macro elements like Ca (3-$$ . that Ca content in individual participants vary.
Low Ca content is interpreted as ingestion of low calcium containing diets. Excess calcium
concentration has no toxicity effect since about 1-2% of the average adult human body is
composed of calcium reserves. K, Na, Mg, Zn and Fe have overall concentration ranges of (7.22
./
044.1-
"$
./
(44.1-"$
./
(45.9-
.
0 -!$
.
34
respectively. The concentrations of As, Cd, Cr, Cu, Ni and Pb may originate from dietary sources
or environmental exposure.
Table 2.
Overall Trace Element Concentrations (µg/g) in all Human Scalp Hair Samples (n=194)
Element
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Average
1.53
3080
0.0316
1.41
25.9
94.7
233
364
12.0
0.868
2.14
349
70.5
Minimum
0.0305
3.00
0.00276
0.0197
1.63
7.22
0.472
44.1
0.0109
0.0245
0.00206
45.9
10.4
Maximum
65.0
177000
2.96
84.6
427
1130
9350
2700
331
34.5
118
10000
697
Std
5.99
14500
0.213
8.44
43.7
135
685
434
39.5
3.01
9.98
1000
100
4.4 Influence of Gender on Trace Element Concentration in Human Hair Scalp.
Table 3 represents the categorization of trace elements concentration into the male and
female participants. The average trace element concentrations of macro element for females were
determined to be Ca (4890±19300 Mg (305±908
! "
# $ ! # % (
#&!'( )! * !# "
essential macro elements in females can be attributed to dietary habits of females. Females are
very conscious of their diet and tend to eat healthier than the average male.59 The average
females also take dietary supplements which are rich in essential trace elements. Essential trace
elements requirement vary with hormonal and physiological requirements. During the onset of
35
menstruation there is a decrease in the amount of Fe in females. This may account for the low
levels Fe in females compared to males. Considering the age of females subject, almost all were
still having their menstrual cycles.60 Other macro elements are high because mothers tend to
have higher amount of trace elements deposits after lactation. High concentration of As in males
may be from diet or environmental exposure. Men are likely to work in environments where As
is likely to bioaccumulate into their scalp hair. Variable concentrations of both essential trace
element and potentially toxic element in females and males can generally be linked to dietary
habits and environmental exposure.
Table 3.
Influence of Gender on Trace Element Concentrations (µg/g) in Human Scalp Hair
Element
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Female (n=108)
Average
Min
Max
0.857
0.141
10.3
4890
3.00
177000
0.0488 0.00352
2.96
1.73
0.0211
84.6
33.9
1.73
427
67.5
7.22
1130
305
0.472
9350
389
55.9
2700
14.0
0.0109
331
0.925
0.0245
34.5
2.29
0.00206
118
474
47.8
10000
61.2
10.4
697
Std
1.48
19300
0.285
9.05
54.5
125
908
492
51
3.49
11.4
1360
94.5
Average
2.39
805
0.010
0.999
15.9
129
142
333
9.37
0.797
1.94
193
82.1
Male (n=86)
Min
Max
0.0305
65.0
19.3
3110
0.0028
0.067
0.0197
71
1.63
138
21.4
739
5.64
524
44.1
2440
0.0353
87.7
0.036
13.8
0.0143
67.9
45.9
919
12.9
560
Std
8.79
635
0.0104
7.64
20.3
141
105
350
15.78
2.29
7.86
112
107
4.5 Influence of Race on Trace Element Concentrations in Human Hair Scalp
Table 4 represents the concentration of trace elements categorized into the African
American and Caucasian races .Out of 194 human subjects, 80 were African American, 85
Caucasians and 29 categorized as other races. Other races comprise of Asian, Hispanics and
36
mixed races. Average concentrations of essential trace element were determined in Caucasians as
On the other hand, concentrations of essential macro elements were determined in African
! " g)
respectively. High concentrations of Ca, Mg and Zn in Caucasians could be
attributed to good dietary habits. Caucasians tends to eat a more balanced diet than the average
African American. Pereira et al reported that fast food patronage frequency was low for
Caucasian women than any other race in the United states 61. This depicts the good eating habits
of Caucasians. The average Caucasian eat lots of dairy products and green leafy vegetables
which are important sources of Ca, Mg and Zn. Interestingly Africa Americans also have high
concentration of some essential macro elements. K, Na and Fe concentrations was determined to
be higher African Americans and these could also be attributed to staple foods ingested by
African American or blacks in general. Foods such as salted pork and collard greens are rich in
these essential macro elements. Table 5 represents concentrations of trace elements determined
in other races. Concentrations of essential trace elements in other races are considerably small
and have no significant effect when compared to African American and Caucasians respectively.
Micro nutrients such as Cu, Cr and Se where determined for African American and Caucasians
! " #$ concentrations of micro elements are within the acceptable threshold hence there is no cause for
alarm. Concentrations of As, Cd and Pb in African American were determined to slightly higher
than those determined in their Caucasian counterparts, sources of these element can be linked to
environmental exposure.
37
Table 4.
Influence of Race on Trace Element Concentration (µg/g) in Human Scalp Hair
Element
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Average
2.82
1090
0.0239
1.18
24.1
133
194
513
17.5
1.51
3.02
183
98.1
0.738
5470
0.0119
2.04
27.3
68.1
295
263
9.64
0.438
1.58
5450
51.1
Minimum
Maximum
0.0305
65.0
5.74
6430
0.00276
0.258
0.0197
71.0
2.07
427
7.83
739
0.472
1050
78.7
2700
0.011
331
0.036
34.5
0.0143
118
47.8
980
10.4
568
Caucasians (n=85)
0.141
22.3
3.00
177000
0.00352
0.0794
0.0211
84.6
1.63
190
7.22
1130
19.0
9350
44.1
1988
0.0121
294
0.0245
11.9
0.00225
67.9
45.9
10000
11.9
697
Std
8.85
1380
0.0418
7.92
51.4
145
195
554
48.7
4.43
13.3
127
114
2.43
21700
0.0131
10.2
35.1
133
1020
298
35.7
1.3
7.41
1520
80.1
38
Table 5.
Influence of Race Trace Element Concentration (µg/g) in Human Scalp Hair
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Average
0.339
1560
0.11
0.186
27.0
66.1
159
250
3.35
0.353
1.32
234
50.9
Others (n=29)
Minimum
Maximum
0.141
1.48
151
4250
0.00352
2.96
0.0211
2.27
3.85
203
11.9
437
13.3
386
86.5
1380
0.0376
21.6
0.0704
1.51
0.00206
24.8
96.1
820
10.8
560
Std
0.287
1360
0.548
0.477
44.6
80.7
108
253
6.1
0.462
4.54
156
100
4.6 Influence of Age on Trace Element Concentrations in Human Scalp Hair
The age ranges chosen for categorizing trace element concentration are as follow 18-24
years, 25-44 years, 45-65 years and 65+ years. Ca which plays vital roles in the formation of
strong bones and teeth.20 ermined for the age range of 25-44 years in
Table 7. This is the highest concentration of Ca among the four age groups. This high
concentration of Ca could be due to the storage of excess calcium ions in the prime age of human
beings. There are no nutritional studies that have indicated the toxicity of calcium thus excess Ca
are store in bones, tissues and the human scalp hair. In Table 9, the aging populations (65+ years)
maintain strong bones and teeth. Age groups of 18-24 years and 45-65 years have Ca
indicated in Table 6 and Table 8 respectively,
39
indicating the onset of Ca storage in bones and hair to its depletion in old age. Macro elements
such as K, Mg, Na, Zn, and Fe also follow the same pattern and peak up in their respective
concentrations as human beings grow and decline in concentration when aging starts. Cu and Se
65+ years indicating high deposits of these two elements in human scalp hair. Concentrations of
these micro elements decline with decrease in the age of subject population which is converse to
the findings of macro elements. Potential toxic elements as As, Cd, Ni, and Pb have variable
concentration in the various group and no pattern recognition can be determined. The maximum
concentration of potential toxic elements were determined to be As -24 year
!!"# #- $ % &# in 25-44 year group respectively.
Table 6.
Influence of Age (18-24) on Trace Element Concentrations (µg/g) in Human Scalp Hair
Element
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Average
2.39
1960
0.0153
1.28
20.2
118
184
373
10.5
0.753
2.50
290
84.4
Age 18-24 years old ( n=96)
Minimum
Maximum
0.0305
65.0
5.74
50700
0.00276
0.258
0.0197
71.0
1.63
115
8.30
739
0.472
1370
60.0
2700
0.0375
331
0.036
13.8
0.0143
118
45.9
6770
10.4
568
Std
8.36
5780
0.029
8.02
22.2
140
200
444
35.6
1.96
12.3
719
115
40
Table 7.
Influence of Age (25-44) on Trace Element Concentrations (µg/g) in Human Scalp Hair
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Average
0.688
6960
0.0172
3.13
30.0
78.1
460
306
8.44
1.64
0.835
526
68.5
Age 25-44 years old ( n=96)
Minimum
Maximum
0.163
4.61
3.00
177000
0.00407
0.115
0.0247
84.6
1.73
203
7.34
1130
22.1
9350
67.0
1990
0.0457
126
0.0815
34.5
0.00225
6.91
47.8
10000
12.9
697
Std
0.869
28800
0.0217
14.1
46.7
182
1510
368
22
5.79
1.18
1630
113
Table 8.
Influence of Age (45-65) on Trace Element Concentrations (µg/g) in Human Scalp Hair
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Average
0.647
2830
0.074
0.61
31.8
66.2
178
350
11.9
0.567
1.14
359
48.4
Age 45-65 years old ( n=51)
Minimum
Maximum
0.141
9.80
4.30
85000
0.00352
2.96
0.0211
15.6
5.12
427
7.22
428
13.3
1230
55.9
2380
0.011
294
0.0245
11.9
0.00206
14.7
89.1
7670
10.8
315
Std
1.39
11800
0.413
2.45
65.3
79.1
198
422
43.9
1.76
2.50
1050
55.4
41
Table 9.
Influence of Age (65+) on Trace Element Concentrations (µg/g) in Human Hair Scalp
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Average
0.959
886
0.024
0.210
36.6
78.3
166
569
38.3
0.658
8.52
211
55.4
Older than 65 years old ( n=10)
Minimum
Maximum
0.141
2.34
34.9
3180
0.00353
0.0584
0.0212
0.364
4.19
138
12.1
191
44.7
486
44.1
1840
0.0353
246
0.0976
1.35
0.117
67.9
87.4
574
18.2
228
Std
0.869
1040
0.0217
0.142
51
69.4
132
616
80.9
0.455
20.9
166
63.3
4.7 Influence of Smoking Habits on Trace Element Concentrations in Human Hair Scalp.
According to the Center for Disease Control and Prevention (CDC), nearly 17 of every
100 U.S. adults aged 18 years or older (16.8%) currently smoke cigarettes. This means an
estimated 42.1 million adults in the United States currently smoke cigarettes.62 Even though
there is a positive correlation between Cd concentration and smoking habits, the concentration of
Cd determined in the scalp hair of smokers were significantly lower than those of non smokers.
In Table 10 and 11, the Cd concentration determined was 0.017 that of smokers and non smokers. Potential toxic elements such as As, Ni and Pb have variable
concentrations in the various categories. ! " # $ %& '
42
concentrations are the highest concentration for each potential toxic element in the three
groupings. Essential trace elements that serve as macro elements were found to be in high
concentrations for non-
,
the concentrations
' % &
respectively, in non-smokers. Conversely
! " # $ %
& ' %&
' %& ' % ' % ' "#" ()$ " "$"
related risks smokers are prone to. Participants with unknown smoking status variable
concentrations of both essential trace element and potentially toxic element thus no direct
relationship can be established with smokers and non smokers.
Table 10.
Influence of Smoking Habits on Trace Element Concentrations (µg/g) in Human Scalp Hair
Element
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Average
0.682
1150
0.017
0.42
16.1
56
151
354
24.8
0.337
0.968
198
44.9
Smoker (n=16)
Minimum
Maximum
0.180
3.66
4.30
4740
0.00451
0.0916
0.0274
2.27
2.07
58.3
16.4
156
0.472
469
60.4
1460
0.0457
246
0.0245
1.83
0.171
5.49
89.1
919
12.6
92.8
Std
0.914
1460
0.0229
0.713
13.9
38.4
130
414
62.9
0.46
1.38
198
29.6
43
Table 11.
Influence of Smoking Habits on Trace Element Concentrations (µg/g) in Human Scalp Hair
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Average
1.84
4000
0.0403
1.94
31.0
89.6
267
362
11.4
0.945
2.60
417
69
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
0.937
1110
0.0107
0.133
17.2
126
169
380
8.95
0.764
1.14
204
81
Non Smoker (n=133)
Minimum
Maximum
0.110
65.0
3.00
177000
0.00276
2.96
0.0211
84.6
1.63
427
7.22
1130
13.3
9350
44.1
2700
0.0110
331
0.0360
34.5
0.00206
116
45.91
10000
10.4
697
Smoking habit not known(n=45)
0.0305
23.3
72.0
5900
0.00328
0.067
0.0197
1.36
4.48
95.8
16.4
739
5.64
866
111
2440
0.0369
79.2
0.0656
13.8
0.0427
13.1
83.2
980
13.2
491
Std
6.93
17500
0.257
10.2
51.1
134
820
442
41.5
3.4
11.9
1230
103
3.44
1200
0.0102
0.259
18.9
155
159
429
15.5
2.24
2.45
144
108
4.8 Influence of Occupation on Trace Element Concentrations in Human Scalp Hair.
Education, healthcare, industry, government, agriculture, unemployed, unknown
occupation and others were the occupational categories that subjects were grouped into. Potential
toxic elements such As, Cd, Ni, and Pb were determined to be highest in different working
be highest in unknown occupation category of
44
workers and these concentrations can stem from previous exposures. Other job categories have
! " #$ % & the highest
determined in variable concentrations in the different occupations. Highest concentration of
'! ( )*) + ! % ! % ,! essential trace element were determined as Ca
unknown occupation. These concentrations of essential trace elements in industry workers show
a good standard of living of industry workers because they can afford a good and decent meal
which provides good amount of essential trace element. Table 12 represents the concentrations of
elements determined in education and healthcare workers. Healthcare workers have relatively
low concentration of potentially toxic element As (0.712 µg/g), Cd (0.0178 µg/g), Cr (0.136
µg/g) and Pb (0.712 µg/g) . These low concentrations of potentially toxic elements can be linked
to the working environments of health care workers. Industrial workers also have variable
concentrations of essential and potentially toxic elements. The highest essential element
concentration (Ca 177000 µg/g) was determined in this category of workers. Interestingly, low
concentration of arsenic (As) was reported in these category. In Table 14 workers in the
agriculture sector have As concentration of 1.55 µg/g. This high concentration may be as a result
of fertilizer and pesticide usage by workers in this sector of the occupation. Some pesticides and
fertilizers contain small concentration of As and with continuous usage it bioaccumulate in the
human body. Chromium concentration (1.83 µg/g) was determined to be relatively high in the
unknown category of workers. This concentration may originate from a variety of sources
because most participants in this category undertake multiple jobs. Concentration of calcium
determined in government workers (3140 µg/g) is three times the concentration determined in
45
unemployed category (1130 µg/g). This is an indication that government workers can afford to
eat good diet rich in essential elements. Concentration of magnesium in government workers is
three times the concentration determined in the unemployed category. Other concentrations
varied widely in the entire occupational categories
Table 12.
Influence of Occupation on Trace Element Concentrations (µg/g) in Human Scalp Hair
Education (n=22)
Element
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Average
1.00
1190
0.0250
0.588
37.2
61.8
176
377
9.90
0.512
1.49
203
60.7
0.712
1290
0.0178
0.136
24.6
55.0
133
413
28.1
2.45
0.966
243
46.3
Minimum
Maximum
0.164
9.80
3
4250
0.00411
0.245
0.0247
8.38
3.85
427
7.34
373
0.472
489
67.0
2380
0.0621
84.5
0.0822
4.90
0.0348
14.7
91.1
820
12.6
315
Healthcare (n=17)
0.163
2.27
14.9
4520
0.00407
0.0568
0.0326
0.513
2.58
203
10.4
161
55.4
283
77.8
1840
0.0205
246
0.0815
34.5
0.0155
3.41
121
919
13.3
228
Std
2.04
12560
0.0511
1.78
89.3
78.5
112
534
20.4
1.02
3.07
160
65.6
0.608
1270
0.0152
0.132
48.6
39.3
65.2
485
65.3
8.28
0.961
193
49.9
46
Table 13.
Influence of Occupation on Trace Element Concentrations (µg/g) in Human Hair Scalp
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Average
0.427
11200
0.0107
4.92
27.7
108
696
377
2.40
0.935
4.02
832
68.5
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
0.476
3140
0.0119
0.0714
42.5
44.1
372
219
2.74
0.454
0.686
181
48.0
Industry (n=18)
Minimum
Maximum
0.141
3.17
7.61
177000
0.00352
0.0794
0.0211
84.6
1.73
138
7.22
1130
13.3
9350
44.1
1990
0.0353
11.3
0.0703
11.9
0.00206
67.9
89.1
10000
10.8
697
Government (n =6)
0.195
0.925
424
6430
0.00487
0.0231
0.0292
0.139
5.5
121
28.2
104
74.3
866
147
369
0.0352
12.2
0.118
1.39
0.126
1.39
130
258
21.1
103
Std
0.707
41300
0.0177
19.9
36.0
260
2166
519
3.49
2.75
15.9
2330
158
0.268
2730
0.00669
0.0401
44.5
29.7
290
78.2
4.73
0.474
0.44
48.1
32.9
From Table 13, the arsenic concentration determined in industry and government workers are
almost similar. High concentrations of Ca (11200 µg/g) was determined in the industry workers
which is approximately four times the concentration determined in government workers. Sodium
concentration determined in industry workers approximately twice that of government workers.
47
Table 14.
Influence of Occupation on Trace Element Concentrations (µg/) In Human Scalp Hair
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Average
1.55
2160
0.0388
0.233
101
99
348
1080
147
0.776
2.33
313
53.3
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
1.31
1130
0.013
0.288
25.0
92.8
127
274
4.13
0.459
1.63
179
54.7
Agriculture (n=2)
Minimum
Maximum
0.58
2.53
1240
3080
0.0145
0.0631
0.087
0.379
13.0
190
49.9
148
284
413
472
1690
0.145
294
0.290
1.26
0.870
3.79
128
498
11.9
94.8
Unemployed(n=28)
0.141
22.3
9.11
5400
0.00352
0.050
0.0211
4.01
3.08
117
8.30
437
19.0
331
63.4
1120
0.0375
37.8
0.0703
5.20
0.0214
24.8
45.9
510
10.4
560
Std
1.38
1310
0.0344
0.206
125
69.5
91.2
861
208
0.688
2.06
261
58.7
4.15
1280
0.0137
0.775
28.9
116.8
86.2
236
8.95
0.984
4.62
103
102
Calcium concentration determined in agriculture workers (2160 µg/g) is approximately twice the
concentration determined in the unemployed category (1130 µg/g). From table 14, magnesium
and sodium concentration in agriculture workers are approximately three and five times more
than the concentrations in unemployed category.
48
Table 15.
Influence of Occupation on Trace Element Concentrations (µg/g) In Human Scalp Hair.
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
Average
2.25
3200
0.0130
1.83
20.1
119
202
354
7.52
0.821
2.44
402
83.2
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
0.611
1260
0.0153
0.0917
22.3
41.5
128
260
0.136
0.426
0.881
216
43.9
unknown occupation (n=86)
Minimum
Maximum
0.0305
65.0
15.3
85000
0.00276
0.115
0.0197
71.0
1.63
189
14.5
739
5.64
1370
60.4
2440
0.0110
79.2
0.0656
13.8
0.0143
118
61.0
7670
12.9
491
Other job categories (n=86)
0.146
3.66
4.30
3660
0.00366
0.0916
0.0219
0.550
2.07
124
12.09
156
19.9
259
56.0
1240
0.000480
0.838
0.0245
1.83
0.113
5.49
90.6
658
14.1
86.4
Std
8.51
10900
0.0159
8.82
24.9
139
224
366
13.4
2.18
12.7
1100
97.1
1.08
1170
0.0269
0.162
36.1
43.5
75.6
363
0.252
0.628
1.63
176
29.9
Table 15 represents unknown occupation and other job categories. Selenium concentration
determined in the unknown workers category was 2.44 µg/g, which is approximately three times
the concentration found in other job category. Concentrations of other trace elements were
widely varied.
49
4.9 Quality Control and Recovery Studies
! " Zn and 20 mg/L Ca and Na were measured every ten samples. An average of 19 total
measurements was made over a four-day period. The percentage recovered was calculated using
the formula below. The percentages obtained for each element is shown in table 16.
Percentage recovery = Concentration spiked- Concentration unspiked
Concentration added
Table 16.
x 100
Percentages of Recovery Studies
Element
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Average % recovery (±s)
103 (±3)
103 (±3)
104 (±4)
102 (±4)
98 (± 4)
103 (±7)
106 (±3)
96 (±3)
103 (±4)
105 (± 5)
101 (±4)
101 (±7)
4.10 Determination of Element Ratio for Possible Diseases Markers
Alterations in the ratio of essential trace elements in human scalp hair are used to
determine the absorption of essential trace element and utilization of essential trace elements in
humans. The trace element ratios are often more significant than the concentration of the trace
elements themselves63. These ratios are used as markers for the determination of the
50
pathogenesis of various diseases such as hypertension, atherosclerosis, diabetes, and pancreatic
cancer64.The determined ratios for this is illustrated in table 17.
4.11 Calcium and Magnesium Ratios
Ca and Mg ratios in most food are in the ratio of 2:1. Recommendations by nutritional
practitioners vary from 4:1 to a 1:1. Ideally, a low Ca/Mg ratio is preferred for proper
of Ca is severely hindered by Mg in high concentration65. Considering the ratio of Ca/Mg in
males (5.67) and females (16); males have their Ca/Mg ratio far above the recommended levels
whiles females have their Ca/Mg three times that of males and eight times above the
recommended level. High ratio of Ca/Mg is related to several health complications. From this
results there is high tendency of both males and females being prone to ailments such as
hypertension and atherosclerosis.66.Comparing Ca/Mg ratio among races, African Americans
have the smallest Ca/Mg ratio. The order of Ca/Mg ratio in the races is African American (5.62),
Caucasians (18.5) and others (9.81). The ratios in all races were above the recommended levels.
This suggest that most of the subjects are susceptible hypertension and arthrosclerosis and other
health related complication66. Smokers and non smokers also have very high ratios which are
significantly higher than acceptable levels.
4.12 Zinc and Copper Ratio
Zinc and copper ratio is influenced by several physiological factors as well as hormonal
factors. Zn in the body is required in large amounts to retain potassium in the human system. A
low Zn/Cu ratio is an indication of reduced thyroid activity. Low ratio also expresses potassium
deficiency. Zn /Cu ratio in males was calculated to be 12.1 and that of females 14.0. High ratio
of Zn and Cu is also an indication of copper deficiency.67 and these can result in decreased
51
glucose clearance, decreased methionine and abnormal cardiac function. Interestingly,
comparing the ratio of Zn/Cu among African American (7.59) and Caucasians (200), the ratio
difference is about 25 fold which is very large indicating the tendency of Caucasians being prone
to abnormal cardiac functions and other health related complication. The difference between the
Zn/Cu ratio among smokers and non-smoker was significantly small .The ideal ratio of Zn and
Cu is 8:163. Comparing the Zn/Cu ratio among the respective age groups, 65+ years has the
minimum ratio of 5.34.
4.13 Calcium and Zinc Ratio
Ca and Zn usually have the same valence or charge in biological system. Employing
f 2 ions have a similar radius and the same valence,
the smaller ion is preferentially incorporated into the solid over the liquid. Zn tends to be smaller
in radius than Ca thus Zn is readily incorporated into biological system than Ca. Higher Ca/Zn
ratio indicates susceptibility to various health complication. Ca/Zn ratio obtained for males
(4.17) and females (10.3) indicates that females are susceptible to health issues such as
gastrointestinal diseases, chronic liver disease and other chronic disease. African American and
Caucasians have their respective ratio to be 5.96 and 1 which is ideal and there is no cause for
alarm. Smokers and non-smokers have their ratios to be 5.81, and 9.59, respectively the ratio of
non-smokers is twice that of smokers indicating a more competitive absorption of Zn. Zn and
Mg ratios are interpreted using their valence and their sizes. Mg is smaller in size thus easily
absorbed in biological tissues. Zn/Mg ratio indicates how zinc and magnesium are competitively
absorbed. All categories of classifications, gender, smoking status and age have an ideal Zn and
Mg ratio except race where Caucasians have ratio of 18.5 and African Americans 0.943. This
52
high ratio in Caucasian is alarming and lead to several chronic diseases. Low ratio has same
effect as high ratio thus African American also face the same risk as Caucasian.
4.14 Sodium and Potassium
This ratio is referred to as life and death ratio. Ideally there should be about 2.4: 1 ratio
Na to K63. High Na intake and low potassium intake are among the risk factors for
hypertension.68 Considering the ratios determined in each category of classification of human
subjects. Females (5.76) Na/K ratio was determined to be twice that of males (2.58). Both ratios
are not too low or too high to cause any health related implications. The ratio of Na/K is
significantly similar for both African American and Caucasians. Smokers tend to have Na/K
ratio of 6.32 and non-smokers 4.04 which implies that smokers have high ratio of Na/K thus
prone hypertension. Na/K ratio among the different age groups are closely related except for 65+
age group which has Na/K ratio of 7.27
4.15 Zinc and Iron Ratio
Competitive interaction occurs for zinc and iron in the human body. Excess iron inhibits
zinc uptake in the human body and vice versa69. Deficiency of iron results in anemia and
deficiency of zinc results in skin conditions. Analyzing the ratios of Zn/Fe, Females have a ratio
Considering the ratio of Zn and Fe among African American (1.87) and Caucasians (107), there
is a wide disparity. The ratio in Caucasian is to high leading to deficiency of iron and its health
implication. Non- higher the ratios, the lesser amount of iron present for bodily function.
53
4.16 Iron and Copper Ratio
Copper and iron are essential for the proper functioning and growth of the human body.
Their function ranges from cellular respiration to electron transport. Disruption in the
equilibrium amounts of Fe and Cu results in abnormal cellular activity. High ratio of Fe/Cu leads
to lipid peroxidation that leads to mitochondrial damage. Too high or low ratios can also lead to
neurological dysfunction63. Analyzing the ratios obtained for males and females; females (1.18)
Fe/Cu ratio was determined to be smaller than that of males(5.16). Fe/Cu ratios determined in
other categories of classification are within the optimum.
Table 17.
Average Ca/Mg, Zn/Cu, Ca/Zn, Mg/Zn, Na/K, Zn/Fe Ratios in Human Scalp Hairs by Category
Ca/Mg
5.67
16.0
Zn/Cu
12.1
14.0
Ca/Zn
4.17
10.3
7.59
200
8.67
5.96
1.00
6.67
0.943
18.5
1.47
Smokers
Non
Smokers
Unknown
7.62
18-24
25-44
45-65
65 +
Male
Female
African
American
Caucasian
Others
Gender
Zn/Mg
1.36
1.55
Race
Zn/Fe
2.35
7.75
Fe/Cu
5.16
1.81
4.07
1.87
1.89
5.62
18.5
9.81
12.3
3.86
1.87
3.86
107
3.78
4.60
Smoking Habits
5.81
1.31
6.32
4.41
2.79
15
6.57
13.5
11.9
9.59
5.44
4.04
3.02
6.04
2.52
2.23
4.71
10.7
15.1
15.9
5.34
14.4
17.5
10.6
5.77
6.76
13.2
7.88
4.2
3.16
3.92
5.29
7.27
3.44
7.68
7.42
3.81
4.18
2.28
1.52
1.51
13.2
13.5
8.83
3.84
4.95
2.72
1.56
1.21
Age Groups
1.58
1.14
2.02
1.27
Overall
1.5
Na/K
2.58
5.76
54
4.17 Evaluation of Significant Difference in Determined Trace Element Concentration
4.17.1 Evaluation of student t-test based on gender
Student t-test analysis was used to evaluate the differences in the determined trace
element concentration in hair samples. Table 18
gender classification. Arsenic, Ca, Cd, Cu, K, Mg, Na, Ni, Zn, and Fe are all statistically
different at 50% confidence interval for both male and female participants. Comparing tcalculated
values to ttabulated values at a 192 degrees of freedom (0.679-0.677), As has a tcalculated value of
1.782, Ca, Cd, Cu, K, Mg Na, Ni Zn, and Fe have tcalculated values of 1.961, 1.261, 2.905, 3.216,
1.655, 0.891, 0.811, 1.910 and 1.443 respectively. This made the genders statistically different at
50% confidence interval because the respective tcalculated values are greater than the ttabulated value
of 0.679-0.677 at 192 degrees of freedom. Chromium, Pb and Se are not statistically different
between male and female at 50% confidence interval. Chromium, Pb and Se have their tcalculated
values to be 0.598, 0.293 and 0.242 respectively which is less than the ttabulated values which has a
range of 0.679-0.677. At 90% confidence interval, ttabulated values ranges from 1.671-1.670 at 192
degrees of freedom. Comparing the tcalculated values of As, Ca, Cu, K, and Zn which are 1.782,
1.961, 2.905, 3.216 and 1.909 respectively are greater than the range of values of ttabulated from
the student test values thus making As, Ca, Cu, K and Zn statistically different for both male and
female at 90% confidence interval. The following values, 1.261, 0.598, 1.655, 0.891, 0.811,
0.293, 0.242 and 1.443 are the tcalculated values of Cd, Cr, Mg, Na, Ni, Pb, Se and Fe respectively.
Statistically these values are not significantly different for the genders at 90% confidence
interval at 192 degrees of freedom because the respective tcalculated values are less than the range
of ttabulated value of 1.671-1.670.
55
Copper and K are statistically different for both male and female at 95% confidence interval.
This is because Cu has a tcalcualted value of 2.905 and K has a tcalcualted value of 3.216 which is
greater than the range of values of ttabulated which is 1.980-1.960 at 95% confidence interval at
192 degrees of freedom.
Table 18.
Evaluation of Differences in Trace Element Concentrations in Men and Women Using Student Ttest (Women, N =108, Men, N=86)
Elements
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
tcalculated
1.782
1.961
1.261
0.598
2.905
3.216
1.655
0.891
0.811
0.293
0.242
1.909
1.443
ttable @ 50 C I
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
ttable @ 90 C I
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
ttable @ 95 C I
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
4.17.2 Evaluation of student t-test based on race
Referring to Table 19, which is classification based on race. As, Ca, Cd, K, Mg, Na, Ni,
Pb, Se, Zn and Fe are statistically different for African Americans and Caucasians at 50%
confidence level. Arsenic has tcalculated value of 2.087, Ca, Cd, K, Mg, Na, Ni, Pb, Se,Zn and Fe
have tcalculated values of 1.802, 2.519, 2.999, 0.871, 3.639, 1.187, 2.136, 0.866, 30.89 and 3.079
respectively. These values are all greater than 0.679-0.677 which is the range of values of ttabulated at 50% confidence interval at 163 degrees of freedom, thus making As, Ca, Cd, K, Mg,
56
Na, Ni, Pb, Se, Zn and Fe statistically different at 50% confidence interval for African
Americans and Caucasians. Considering Cr and Cu with tcalculated values of 0.602 and 0.469
respectively, Cr and Cu are not statistically different between the two races, because at 50%
confidence interval the tcalculated values are less than that of t-tabulated which is in the range of
0.679-0.677. The range of values for ttabulated at 90% confidence interval at 163 degrees of
freedom is 1.671-1.658. Arsenic, Ca, Cd, K, Na, Pb, Zn and Fe have tcalculated values of 2.087,
1.802, 2.519, 2.999, 3.639, 2.136, 30.89, and 3.079 respectively. These values are greater than
the range of values for t-tabulated at 90% confidence interval thus making the values of As, Ca,
Cd, K, Na, Pb, Zn and Fe significantly different at 90% confidence interval between African
American and Caucasians. Comparatively, Cr, Cu, Mg, Ni and Se are not significantly different
because their respective tcalculated values of 0.602, 0.469, 0.871, 1.187, and 0.866 are all less than
the range of values of ttabulated which is 1.671-1.658 at 90% confidence interval and 163 degrees
of freedom. Examining the tcalculated values of As, Cd, K, Na, Pb Zn and Fe at 95% confidence
interval, As has value of 2.087, Cd, K, Na, Pb Zn and Fe has values of 2.519, 2.999, 3.639,
2.136, 30.89 and 3.079 sequentially. Comparing the tcalculated values to that of ttabulated at 95%
confidence interval, there is statistical difference between African Americans and Caucasians at
163 degrees of freedom for As, Cd, K, Na, Pb Zn and Fe because their tcalculated values are greater
than the range of values for ttabulated which is in the range of 1.980-1.960. Conversely, Ca, Cr, Cu,
Mg, Ni and Se are not statistically different for the two races at 95% confidence interval because
their respective tcalculated values of 1.802, 0.602, 0.469, 0.8707, 1.187, and 0.866 are less than ttabulated values which are in the range of 1.980-1.960.
57
Table 19.
Evaluation of Differences in Trace Element Concentration in Race Using Student T-test (African
American, N =80, Caucasian, N=85)
Elements
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
tcalculated
2.087
1.802
2.519
0.602
0.469
2.999
0.871
3.639
1.187
2.136
0.866
30.89
3.079
ttable @ 50CI
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
ttable @ 90CI
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
ttable @ 95CI
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
4.17.3 Evaluation of student t-test based on smoker status
Referring to calculation based on smoking habits at 50% confidence interval in table 20,
Cu, K, Ni, Pb, Zn and Fe are statistically different because their tcalculated values of 1.158, 0.995,
1.147, 0.712, 0.709 and 0.929 are all greater than ttabulated values with the range of 0.6790.677.On the other hand, As, Ca, Cd, Cr, Mg, Na and Se with their respective tcalculated values of
0.666, 0.649, 0.361, 0.594, 0.563, 0.069, and 0.547 are all less than the range of values for
ttabulated which has a range of 0.679-0.677 at 147 degrees of freedom. At 90% confidence
interval, there is no statistical difference between smokers and non smokers because As, Ca, Cd,
Cr, Cu, K, Mg, Na, Ni, Pb, Se, Zn and Fe with their respective values of 0.667, 0.649, 0.361,
0.594, 1.158, 0.995, 0.5634, 0.069, 1.147, 0.712, 0.547, 0.709, and 0.929 are less than the range
of values for ttabulated which ranges from 1.658 to 1.671 at 147 degrees of freedom.
58
Statistically there is no difference at 95% confidence interval between smokers and non smokers
because As has a tcalculated value of 0.666, Ca, Cd, Cr, Cu, K, Mg, Na, Ni, Pb, Se, Zn and Fe have
their respective tcalculated value to be 0.649, 0.361, 0.594, 1.158, 0.995, 0.563, 0.069, 1.147, 0.712,
0.5465, 0.709 and 0.929.
Table 20.
Evaluation of Differences in Trace Element Concentration in Smokers and Non-Smokers Using
Student T-test (Smokers, N =16, Nonsmoker, N=133)
Elements
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
tcalculated
0.666
0.649
0.361
0.594
1.158
0.995
0.563
0.069
1.147
0.712
0.547
0.709
0.929
ttable @ 50CI
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
0.679-0.677
ttable @ 90CI
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
1.671-1.658
ttable @ 95CI
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
1.980-1.960
4.18 Overall Inter Element Associations in Human Scalp Hair
The concentrations of the trace elements determined in the hair samples were subjected to
multiple regression analysis in order to evaluate inter-element association. Table 21 is the result
of inter-element association in hair samples. There was no inter-elemental association between
As and any the analyzed trace element for the total classification. Ca expressed a weak
association with Cr (R2 = 0.55) and a strong relationship with Mg (0.85) and Zn (R2 =0.88). Cr
was also determined to be weakly associated with Ca (R2 = 0.55). K and Fe had correlation
59
coefficient of 0.52 which depicts a weak association. Mg is strongly associated with Ca with an
R2 value of 0.85 and weakly associated with Zn (R2 =0.61).
Table 21.
Overall Inter-Element Association in Human Scalp Hair
Element As
As
X
Ca
0
Cd
0
Cr
0
Cu
0
K
0.05
Mg
0
Na
0.06
Ni
0
Pb
0
Se
0
Zn
0
Fe
0.04
Ca
0
X
0
0.55
0
0.33
0.85
0.07
0
0
0
0.88
0.22
Cd
0
0
X
0
0
0
0
0.07
0
0
0
0
0
Cr
0
0.55
0
X
0
0.22
0.05
0
0
0
0
0.47
0.14
Cu
0
0
0
0
X
0
0
0
0.02
0
0
0
0
K
0.05
0.33
0
0.22
0
X
0.37
0.44
0.02
0.02
0
0.27
0.52
Mg
0
0.85
0
0.05
0
0.37
X
0.14
0
0
0
0.61
0.3
Na
0.06
0.07
0.07
0
0
0.44
0.14
X
0.37
0.02
0
0.06
0.3
Ni
0
0
0
0
0.02
0.02
0
0.37
X
0
0
0
0.11
Pb
0
0
0
0
0
0.02
0
0.02
0
X
0
0
0.06
Se
0
0
0
0
0
0
0
0
0
0
X
0
0
Zn
0
0.88
0
0.47
0
0.27
0.61
0.06
0
0
0
X
0.19
Fe
0.04
0.22
0
0.14
0
0.52
0.3
0.3
0.11
0.06
0
0.19
X
4.19 Inter-Element Association between Males and Females
Considering the inter-element associations between genders in table 22, there was strong
correlation between As and Na in females (R2 =0.7) and weak correlation between As and Fe (R2
=0.5). There was no correlation for males. Ca weakly correlated with Fe (R2 =0.5) and strongly
with K (R2 =0.8), Mg (R2 =0.9) and Zn (R2 =0.9) in females. Strong inter- elemental association
existed between Cr and K (R2 =0.8), Mg (R2 =0.9) and Zn (R2 =0.8) in females. However strong
correlation was determined to exist between K and Ca (R2 =0.8), K and Cr (R2 =0.8), K and Mg
(0.8), K and Zn (R2 =0.7) and K and Fe (R2 =0.7) in females. Inter element association also
existed between Mg and Ca (R2 =0.9), Mg and Cr (R2 = 0.9), Mg and K (R2 =0.8), Mg and (R2
=0.7) and Mg and Fe (R2 =0.7) in females only. Fe has weak association with As (R2 =0.5), Ca
(R2 =0.5), Cr (R2 =0.5) and Na(R2 =0.5). Strong correlations existed when Fe and K (R2 =0.7).
60
Table 22.
Inter-Elemental Association in Male and Female
As
M
F
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
X
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.2
0.0
0.1
0.0
0.7
0.0
0.4
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.5
Ca
M
F
0.0
0.0
X
0.0
0.0
0.0
0.2
0.1
0.0
0.0
0.8
0.4
0.9
0.0
0.1
0.2
0.0
0.1
0.0
0.0
0.0
0.2
0.9
0.0
0.5
Cd
M
F
0.0
0.0
0.0
0.0
X
0.0
0.0
0.0
0.0
0.1
0.0
0.2
0.0
0.1
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Cr
M
F
0.0
0.0
0.0
0.2
0.0
0.0
X
0.0
0.0
0.0
0.8
0.0
0.9
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.8
0.0
0.5
Cu
M
F
0.0
0.0
0.1
0.0
0.0
0.0
0.0
0.0
X
0.0
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
01
0.0
0.0
0.0
K
M
F
0.0
0.2
0.0
0.8
0.1
0.0
0.0
0.8
0.0
0.0
X
0.0
0.8
0.6
0.4
0.0
0.0
0.1
0.0
0.0
0.0
0.0
0.7
0.4
0.7
Mg
M
F
0.0
0.1
0.4
0.9
0.2
0.0
0.0
0.9
0.1
0.0
0.0
0.8
X
0.2
0.2
0.2
0.0
0.0
0.0
0.0
0.0
0.1
0.6
0.3
0.6
Na
M
F
0.0
0.7
0.0
0.1
0.1
0.0
0.0
0.1
0.0
0.0
0.6
0.4
0.2
0.2
X
0.0
0.5
0.0
0.0
0.0
0.0
0.0
0.1
0.1
0.5
Ni
M
F
0.0
0.4
0.2
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.2
0.0
0.0
0.5
X
0.0
0.0
0.0
0.0
0.3
0.0
0.0
0.2
Pb
M
F
0.0
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
X
0.0
0.0
0.0
0.0
0.2
0.0
Se
M
F
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
X
0.0
0.0
0.0
0.0
Zn
M
F
0.0
0.0
0.2
0.9
0.0
0.0
0.0
0.8
0.1
0.0
0.0
0.7
0.1
0.6
0.0
0.1
0.3
0.0
0.0
0.0
0.0
0.0
X
0.0
0.4
Fe
M
F
0.0,
0.5
0.0
0.5
0.0
0.0
0.0
0.5
0.0
0.0
0.4
0.7
0.3
0.6
0.1
0.5
0.0
0.2
0.2
0.0
0.0
0.0
0.0
0.4
X
4.20 Inter Elemental Association in Race
From table 23, strong inter-element associations were determined with Ca and Cr, K,
Mg, Zn and Fe to be 0.9. Cd and Na strongly correlated with a value of 0.7. Zinc and Ca
exhibited a strong correlation (R2 =0.9). Interestingly strong correlation also existed between Fe
and other major trace element with R2 values ranging from 0.6 to 0.9.
61
Table 23.
Inter-Elemental Association in African American (AA) and Caucasian (CC)
As
As
Ca
Cd
Cr
Cu
K
Mg
Na
Ni
Pb
Se
Zn
Fe
AA
CC
AA
CC
0.0
0.0
AA
CC
0.0
0.0
0.0
0.3
AA
CC
0.0
0.0
0.0
0.9
0.0
0.3
AA
CC
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
AA
CC
0.1
0.0
0.0
0.9
0.0
0.5
0.0
0.9
0.0
0.0
AA
CC
0.0
0.0
0.4
0.9
0.4
0.4
0.0
0.9
0.0
0.0
0.0
0.9
AA
CC
0.1
0.0
0.0
0.5
0.5
0.7
0.0
0.4
0.0
0.0
0.4
0.6
0.2
0.5
AA
CC
0.0
0.0
0.0
0.0
0.5
0.2
0.0
0.0
0.0
0.2
0.0,
0.0
0.2
0.0
0.4
0.4
AA
CC
0.0
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
AA
CC
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
AA
CC
0.0
0.0
0.0
0.9
0.0
0.3
0.0
0.8
0.1
0.0
0.0
0.7
0.0
0.6
0.0
0.4
0.0
0.0
0.0
0.0
0.0
0.0
AA
CC
0.0
0.0
0.0
0.9
0.2
0.5
0.0
0.9
0.0
0.0
0.3
0.9
0.3
0.9
0.2
0.6
0.2
0.0
0.1
0.0
0.0
0.0
0.0,
0.8
X
0.0
Ca 0.0
0.0
Cd 0.0
0.0
Cr 0.0
0.0
Cu 0.0
0.1
K 0.0
0.0
Mg 0.0
0.1
Na 0.0
0.0
Ni 0.0
0.0
Pb 0.0
0.0
Se 0.0
0.0
Zn 0.0
0.0
Fe 0.0
X
0.0 0.3
0.0
0.9
0.0
0.0
0.0
0.9
0.4
0.9
0.0
0.5
0.0
0.0
0.1 0.0
0.0
0.0
0.0
0.9
0.0
0.9
X
0.0
0.3
0.0
0.0
0.0
0.5
0.4
0.4
0.5
0.7
0.5
0.2
0.0
0.0
0.0
0.0
0.0
0.3
0.2
0.5
X
0.0
0.0
0.0
0.9
0.0
0.9
0.0
0.4
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.8
0.0
0.9
X
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.2
0.0
0.0
0.0
0.0
0.1
0.0
0.0
0.0
X
0.0
0.9
0.4
0.6
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.7
0.3
0.9
X
0.2
0.5
0.2
0.0
0.0
0.0
0.0
0.0
0.0
0.6
0.3
0.9
X
0.4
0.4
0.0
0.0
0.0
0.0
0.0
0.4
0.2
0.6
X
0.0
0.0
0.0
0.0
0.0
0.0
0.2
0.0
X
0.0
0.0
0.0
0.0
0.1
0.0
X
0.0
0.0
0.0
00
X
0.0
0.8
X
4.21 Inter Elemental Association in Smokers and Non Smokers
From table 24, As has very strong correlation with Cd (R2 =1), Pb (R2 =1) and Se (R2 =1)
in smokers this interesting evidence stem from the fact that Cd accumulates in tobacco plants 71.
This result gives an indication of potential exposure of smokers to toxic element.
62
Table 24.
Inter-Element Association in Smokers (SM) and Non-Smoker (NS)
As
SM
NS
As
X
0.0
Ca 0.0
1.0
Cd 0.0
0.0
Cr 0.0
0.0
Cu 0.0
0.7
K 0.1
0.0
Mg 0.0
0.7
Na 0.1
0.1
Ni 0.0
1.0
Pb 0.0
1.0
Se 0.0
0.0
Zn 0.0
0.3
Fe 0.1
Ca
SM
NS
Cd
SM
NS
Cr
SM
NS
Cu
SM
NS
0.0
0.0
1.0
0.0
0.0
0.0
0.0
0.0
0.0
0.5
0.0
0.0
0.0
0.0
0.7
0.0
0.0
0.0
0.0
0.0
X
0.0
0.0
0.0
0.5
0.7
0.0
0.0
0.5
0.7
0.9
0.0
0.1
0.0
0.0
0.0
0.0
0.1
0.0
0.2
0.9
0.1
0.3
X
0.0
0.0
0.0
0.0
0.7
0.0
0.1
0.0
0.7
0.1
0.1
0.0
1.0
0.0
1.0
0.0
0.0
0.0
0.3
0.0
X
0.0
0.0
0.2
0.3
0.3
0.5
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.5
0.4
0.2
X
0.1
0.0
0.4
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.0
0.0
0.0
K
SM
NS
0.7
0.1
0.0
0.5
0.7
0.0
0.2
0.3
0.1
0.0
X
0.2
0.5
0.7
0.4
0.2
0.0
0.7
0.0
0.7
0.0
0.0
0.4
0.6
0.6
Mg
SM
NS
0.0
0.0
0.7
0.9
0.1
0.0
0.3
0.5
0.4
0.0
0.2
0.5
X
0.1
0.2
0.0
0.0
0.1
0.0
0.0
0.0
0.1
0.6
0.3
0.4
Na
SM
NS
0.7
0.1
0.0
0.1
0.7
0.1
0.0
0.1
0.0
0.0
0.7
0.4
0.1
0.2
X
0.6
0.5
0.7
0.0
0.7
0.0
0.0
0.1
0.3
0.5
Ni
SM
NS
0.1
0.0
0.0
0.0
0.1
0.0
0.0
0.0
0.0
0.0
0.2
0.0
0.0
0.0
0.6
0.5
X
0.1
0.0
0.1
0.0
0.1
0.0
0.1
0.2
Pb
SM
NS
1.0
0.0
0.0
0.0
1.0
0.0
0.0
0.0
0.0
0.0
0.7
0.0
0.1
0.0
0.7
0.0
0.1
0.0
X
1.0
0.0
0.0
0.0
0.4
0.0
Se
SM
NS
1.0
0.0
0.1
0.0
1.0
0.0
0.0
0.0
0.0
0.0
0.7
0.0
0.0
0.0
0.7
0.0
0.1
0.0
1.0
0.0
X
0.0
0.0
0.2
0.0
Zn
SM
NS
Fe
SM
NS
0.0
0.0
0.2
0.9
0.0
0.0
0.0
0.5
0.1
0.0
0.0
0.4
0.1
0.6
0.0
0.1
0.1
0.0
0.0
0.0
0.0
0.0
0.3
0.1
0.1
0.3
0.3
0.0
0.4
0.2
0.0
0.0
0.6
0.6
0.3
0.4
0.3
0.5
0.1
0.2
0.4
0.0
0.2
0.0
0.0,
0.3
X
0.0
0.3
X
63
CHAPTER 5
Conclusion
The concentrations of essential macro element were determined to be the highest in
human scalp hair. The average concentration of
! potentially toxic element were also determined. The use of microwave assisted sample digestion
proved to be very efficient and less time consuming. This technique was very helpful to prevent
sample loss through spillage or splashing. Multiple sample digestion was made possible because
MARS CEM Microwave can digest multiple samples simultaneously. The use of Flame Atomic
Absorption Spectrometer (FAAS) was also efficient in determination of Fe but could not
determine other micro elements such a Se, Ni because these elements are in small concentrations.
The use of inductively coupled plasma spectrometer to determine the concentrations of As, Cd
Cr, Mg, K, Ca, Cu, Na, Zn, Ni, Se and Pb provided the advantages of yielding a better detection
limits of all elements than that obtained for FAAS analysis. It also provided the advantage of
auto sampling with a higher sensitivity and precision. Categorization of trace element into their
respective demographics (age, gender, occupation and smoking status) played a key role in the
concentration of each trace element determined in each subject. An illustration is the high
concentration of ess
"
"
# $ " "%
determined in females than males. And this is due to the healthy lifestyle of an average female
than a male. The use of human scalp hair for the determination of essential and potential toxic
elements proved to be efficient and rapid technique.
64
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