Post on 11-Jan-2022
CHARACTERIZATION OF THE GEOPHAGIC MATERIALS AND THEIR
OVERLYING ROCKS AND SOILS FROM ANFOEGA, GHANA
THIS THESIS IS SUBMITTED TO THE UNIVERSITY OF GHANA, LEGON IN
PARTIAL FULFILMENT OF THE REQUIREMENT FOR THE AWARD OF
MASTER OF PHILOSOPHY IN SOIL SCIENCE
BY
JUSTICE KWESI BADU
10507248
JULY, 2016
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DECLARATION
I hereby declare that this thesis “Characterization of the geophagic materials and their
overlying rocks and soils from Anfoega, Ghana” has been written by me and that it is the
record of my own research work. It has neither in whole nor in part been presented for
another degree elsewhere. Works of other researchers have been duly cited by references
to the authors and all assistance received also acknowledge.
……………………
JUSTICE KWESI BADU
(Student)
……………………
Dr. T. A. ADJADEH
(Supervisor)
…………………
Dr. D. E. DODOR
(Co-supervisor)
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ABSTRACT
Geophagy is the deliberate consumption of earth and clay deposits by animals, including
man. It is a special type of pica, which is defined as the craving and subsequent
consumption of non-food substances. This study was conducted to examine the physical,
chemical and mineralogical properties of the geophagic materials and their overlying rocks
and soils from four sites at Anfoega in order to determine possible relationships among
them and the potential human health risk associated with the consumption of the geophagic
materials. The four sites were Tokorme 1, Tokorme 2, Tokorme 3 and Wuve. Soil samples
and geophagic materials from the selected sites were subjected to the following laboratory
analyses: colour, particle size distribution, pH, electrical conductivity, cation exchange
capacity, organic carbon content and X-ray defractometry. The rock samples and
geophagic materials were also subjected to petrographic and x-ray analysis. Whereas the
pH of the soils from Tokorme 1, Tokorme 3 and Wuve ranged from slightly acidic to
moderately acidic, that of Tokorme 2 was moderately acidic in the surface soils but strongly
acidic in the lower layers. The pH of the geophagic materials was strongly acidic. While
the soil samples generally contained high amounts of sand, the geophagic materials
contained high amounts of clay. With higher amounts of clay, the CEC of the geophagic
materials ranged from 18.0 to 23.2 cmolc kg-1 which was higher than that of the soil
samples (5.3 to 22.6 cmolc kg-1). The thin sections of the rocks showed very high amounts
of quartz and small amounts of feldspars and sericite. The thin sections of the geophagic
materials on the other hand, revealed the presence of large amounts clay and some quartz,
feldspars and sericite. The x-ray diffractograms showed that the soils, rocks, and geophagic
materials were dominated by SIALIC minerals mainly quartz, kaolinite, muscovite and
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feldspar. The mineralogy of the soils indicated that they were derived in-situ from the
underlying sandstones. The results also showed that the high amounts of SIALIC minerals
in the geophagic materials was accumulated through leaching of the overlying sandstone.
The health risk index analysis of the geophagic materials calculated based on consumption
of 70 g of clay per day were all less than 1.0. This result indicates that the geophagic
materials were safe for human consumption. Also, the microbial analysis of the geophagic
materials showed high levels of bacteria load in the processed fresh, processed dry,
powdered and smoked samples. However, no coliform group was detected. The microbial
results showed that although the geophagic materials were naturally safe for consumption,
processing them could introduce harmful micro-organisms.
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DEDICATION
The entire work is dedicated to my beautiful and lovely wife Mrs. Roselyn Korkor Badu
and my beloved daughter Maame Akosua Adum.
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ACKNOWLEDGEMENTS
I want to acknowledge the intellectual contributions and support I received from my
Supervisor, Dr. T. A. Adjadeh. I cannot think of anything connected with this work that
has not benefited from his efforts and insight. I am highly indebted to him for his
contributions, ideas and inputs that have really shaped this work. He has readily assisted
me to clarify many of the technical issues and I owe much to him for this. I am equally
indebted to my co-supervisor, Dr. Daniel E. Dodor for his useful suggestions and
cooperation. He has directly and indirectly inspired much of the effort that has gone into
this work.
I wish to sincerely thank Mr. Bernard Anipa, Chief Technician of the Department of Soil
Science for the great help he gave me during the fieldwork at Anfoega. I also wish to thank
the other Technicians, Messrs Victor Adusei-Okrah, and Martin Aggrey for their help
during the laboratory investigations.
It is a pleasure to acknowledge Professor P. M. Nude (Department of Earth Science),
Professor B. B. Kayang (Department of Animal Science), Dr. Martin Egblewogbe
(Department of Physics) and Mr Joseph Eyram Dzata (Department of Computer Science)
for their invaluable assistance offered me during my laboratory work. I am so grateful and
I appreciate everything they contributed towards the success of this project.
I am very grateful to my family for the invaluable help they gave me during the period of
the research work. I am highly indebted to my wife and daughter for their patience when I
was preoccupied with writing the thesis. My mother, Madam Akosua Adum also deserve
special recognition for her support during the period of the MPhil Programme.
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TABLE OF CONTENTS
DECLARATION…………………………………………………………………………i
ABSRACT………………………………………………………………………………..ii
DEDICATION ............................................................................................................................ ..iv
ACKNOWLEDGEMENTS .......................................................................................................... v
TABLE OF CONTENTS ............................................................................................................. vi
LIST OF FIGURES ..................................................................................................................... xii
LIST OF TABLES ...................................................................................................................... xiv
LIST OF ABBREVIATIONS .................................................................................................... xvi
INTRODUCTION.......................................................................................................................... 1
CHAPTER TWO ........................................................................................................................... 6
LITERATURE REVIEW ............................................................................................................. 6
2.1 Overview .......................................................................................................................... 6
2.2 Definition of Geophagy ................................................................................................... 6
2.3 Historical Overview ......................................................................................................... 7
2.4 Aetiology of Geophagy .................................................................................................... 9
2.4.1 Geophagy for Cultural and Religious Purposes ...........................................10
2.4.2 Geophagy as a Food Supplement .................................................................11
2.4.3 Soil as Medicine or Medicament .................................................................12
2.4.4 Soil as Food Additives and Detoxifier .........................................................12
2.4.5 Psychiatric and Physiological Causes of Geophagy ....................................13
2.5 Health Implications of Geophagy .................................................................................. 13
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2.6 Geophagy: Reports from Ghana .................................................................................... 15
2.7 Geology of the mining site at Anfoega .......................................................................... 16
2.8 Vegetation of Anfoega ................................................................................................... 17
2.9 Chemical Composition of Geophagic Materials ............................................................ 17
2.10 Mineralogical Composition of Geophagic Clays ........................................................... 18
2.11 Biological Properties of Geophagic Clays ..................................................................... 19
2.12 Effects of Microorganisms Associated with Geophagy on Humans ............................. 21
2.13 Effects of Heavy Metals Associated with Geophagy on Humans ................................. 22
2.14 Mining of Geophagic Materials Worldwide .................................................................. 23
2.15 Processing of Geophagic Materials................................................................................ 24
2.16 Marketing of Geophagic Materials ................................................................................ 24
CHAPTER THREE ..................................................................................................................... 26
MATERIALS AND METHODS ................................................................................................ 26
3.1 Site Selection and Description ....................................................................................... 26
3.2 Sample Collection and Storage ...................................................................................... 27
3.3 Physical Analysis ........................................................................................................... 29
3.3.1 Bulk Density of the Soil Samples ................................................................29
3.3.2 Particle Size Distribution .............................................................................30
3.3.3 Soil Colour ...................................................................................................31
3.4 Chemical Analysis ......................................................................................................... 31
3.4.1 pH (H2O) ......................................................................................................31
3.4.2 pH (CaCl2) ...................................................................................................32
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3.4.3 Electrical Conductivity ................................................................................32
3.4.4 Organic Carbon ............................................................................................32
3.4.5 Total Nitrogen ..............................................................................................33
3.4.6 Cation Exchange Capacity ...........................................................................34
3.4.7 Determination of Exchangeable Bases ........................................................35
3.4.8 Determination of Total Phosphorus .............................................................35
3.4.9 Available Phosphorus ..................................................................................36
3.4.9.1 Olsen’s Extraction Procedure ........................................................................... 36
3.4.9.2 Bray 1 Method ................................................................................................... 36
3.5 Mineralogical Analysis .................................................................................................. 37
3.5.1 Thin Section Preparation and Petrographic Examination of Rock Samples 37
3.5.2 Fractionation of Samples .............................................................................38
3.5.3 Potassium Saturation of Exchange Complexes............................................38
3.5.4 Sample Preparation ......................................................................................39
3.5.5 X-Ray diffraction .........................................................................................39
3.6 Heavy Metal Analysis .................................................................................................... 39
3.7 Microbial Analysis of the Geophagic Materials ............................................................ 41
3.8 Questionnaire to solicit information on the ingestion of the geophagic materials from
Anfoega…………………………………………………………………………………..41
CHAPTER FOUR ........................................................................................................................ 43
RESULTS ..................................................................................................................................... 43
4.1 Morphological Properties of the Soils ........................................................................... 43
4.2 Physical Properties ......................................................................................................... 46
4.2.1 Particle Size Distribution and Texture .........................................................46
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4.2.2 Bulk Density ................................................................................................46
4.3 Chemical Properties ....................................................................................................... 48
4.3.1 pH Water and pH Calcium Chloride of the Soils and the Geophagic
Materials…………………………………………………………………..48
4.3.2 Electrical Conductivity ................................................................................48
4.3.3 Total Nitrogen Content of the Soils and Associated Geophagic Materials .49
4.3.4 Organic Carbon Content of the Soils and the geophagic materials .............49
4.3.5 Phosphorus Content (Total and Available) of the Soils and the Geophagic
Materials…………………………………………………………………..49
4.3.6 Exchangeable Bases and Cation Exchange Capacity of the Soils and
Geophagic Materials……………………………………...……………….52
4.4 Mineralogical Composition of the Rocks, Geophagic Materials and Soils ................... 54
4.4.1 Thin Section Petrography of Rock Samples ................................................54
4.4.1.1 Thin Section of Rock Sample from Tokorme 1 ................................................ 54
4.4.1.2 Thin Section of Rock Samples from Tokorme 2 .............................................. 55
4.4.1.3 Thin Section of Rock Samples from Tokorme 3 .............................................. 56
4.4.1.4 Thin Section of Rock Samples from Wuve ....................................................... 57
4.4.2 Thin Sections of Geophagic Materials .........................................................59
4.4.2.1 Thin Section of Geophagic Materials from Tokorme 1 ................................... 59
4.4.2.2 Thin Section of Geophagic Materials from Tokorme 2 ................................... 60
4.4.3 X-Ray Diffractograms of Rock Samples .....................................................61
4.4.4 X-Ray Diffractogram of the Geophagic Materials ......................................64
4.4.5 X-Ray Diffractograms of Soil Samples (clay fractions) ..............................66
4.5 Heavy Metal Content of the Geophagic Materials ......................................................... 69
4.5.1 Health Risk Index (HRI) Analyses of Heavy Metals in the Geophagic
Materials…………………………………………………………………..70
4.6 Microbiological Analysis ............................................................................................... 73
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4.7 Responses from the Interviews ...................................................................................... 75
4.7.1 Miners ..........................................................................................................75
4.7.2 Dealers (women involved in the processing and marketing) .......................75
4.7.3 Health Personnel ..........................................................................................76
CHAPTER FIVE ......................................................................................................................... 77
DISCUSSION ............................................................................................................................... 77
5.1 Physical Properties ......................................................................................................... 77
5.1.1 Particle Size Distribution and Texture…………………………………….76
5.1.2 Bulk Density ................................................................................................77
5.2 Chemical Properties ....................................................................................................... 78
5.2.1 pH (H2O) and pH (CaCl2) of Soils and Geophagic Materials .....................78
5.2.2 Electrical Conductivity ................................................................................79
5.2.3 Total Nitrogen Content ................................................................................79
5.2.4 Organic Carbon ............................................................................................79
5.2.5 Available Phosphorus and Total Phosphorus content of the Soils and
Geophagic Materials………………………………………………………80
5.2.6 Exchangeable Bases and Cation Exchange Capacity ..................................80
5.3 Mineralogy ..................................................................................................................... 81
5.3.1 Thin Section Petrography of the Geophagic Materials and Rocks ..............81
5.3.2 X-Ray Examination .....................................................................................81
5.3.2.1 The X-ray Diffractograms of Rocks ................................................................. 81
5.3.2.2 The X-ray Diffractograms of the Soils ............................................................. 81
5.3.2.3 The X-ray Diffractograms of the Geophagic Materials ................................... 82
5.4 Levels of Heavy Metals (HM) in Geophagic Materials ................................................. 82
5.5 Microbial Analysis ......................................................................................................... 83
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5.5.1 Heterotrophic Bacterial Count and Coliform Numbers in the Geophagic
Meterials…………………………………………………………………..83
5.6 Questionnaire ................................................................................................................. 84
CHAPTER SIX ............................................................................................................................ 85
CONCLUSIONS AND RECOMMENDATIONS ..................................................................... 85
6.1 Conclusions………………………………………………………………………84
6.2 Recommendations……………………………………………………………......85
REFERENCES ............................................................................................................................. 88
APPENDICES ............................................................................................................................ 105
Appendix A .............................................................................................................................. 105
Questionnaire for Consumers ...................................................................................105
Appendix B .............................................................................................................................. 106
Questionnaire for Dealers in White Clay Business ..................................................106
Appendix C .............................................................................................................................. 107
Questionnaire for Miners ..........................................................................................107
Appendix D .............................................................................................................................. 109
Questionnaire for Health Facilities / EPA ................................................................109
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LIST OF FIGURES
Fig. 1a Location of study sites………………………………………………………….27
Fig. 1b Vertical cross-section of a pit indicating the position of the geophagic
materials….………………………………………………………………………28
Fig. 2a Sandstone showing sub-rounded to rounded grains cemented by iron oxide in
rock sample from Tokorme 1…………………………………………………….55
Fig. 2b Sub-rounded to rounded grains cemented by iron oxide in rock sample from
Tokorme 2……………………………………………………………………….56
Fig. 2c Sutured and recrystallized quartz in rock sample from Tokorme 3……………...57
Fig. 2d Sandstone with poorly-sorted grains that are slightly elongated in rock sample
from Wuve……………………………………………………………………….58
Fig. 3a Thin lamination of the geophagic materials from Tokorme 1…………………...60
Fig. 3b Silty-sand size quartz grains occurring as impregnation within the fine grained
matrix of sericite in geophagic materials from Tokorme 2………………………61
Fig. 4a X-ray diffractogram of a rock from Tokorme 1………………………………….62
Fig. 4b X-ray diffractogram of a rock from Tokorme 2………………………………….62
Fig. 4c X-ray diffractogram of a rock from Tokorme 3………………………………….63
Fig. 4d X-ray diffractogram of a rock from Wuve……………………………………….63
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Fig. 5a X-ray diffractograms of K-25, K-350, and K-550 clay fraction of the geophagic
materials from Tokorme 1………………………………………………………64
Fig. 5b X-ray diffractograms of K-25, K-350, and K-550 clay fraction of the geophagic
materials from Tokorme 2………………………………………………………65
Fig. 5c X-ray diffractograms of K-25, K-350, and K-550 clay fraction of the geophagic
materials from Tokorme 3………………………………………………………65
Fig. 5d X-ray diffractograms of K-25, K-350, and K-550 clay fraction of the geophagic
materials from Wuve……………………………………………………………66
Fig. 6a X-ray diffractograms of K-25, K-350, and K-550 clay fraction of soil from
Tokorme 1………………………………………………………………………..67
Fig. 6b X-ray diffractograms of K-25, K-350, and K-550 clay fraction of soil from
Tokorme 2………………………………………………………………………..68
Fig. 6c X-ray diffractograms of K-25, K-350, and K-550 clay fraction of soil from
Tokorme 3………………………………………………………………………..68
Fig. 6d X-ray diffractograms of K-25, K-350, and K-550 clay fraction of soil from
Wuve……………………………………………………………………………..69
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LIST OF TABLES
Table 4.1 Morphological properties of the soils……………………………………45
Table 4.2 Selected physical properties of the soils…………………………………47
Table 4.3 Selected chemical properties of the soils and geophagic materials……...51
Table 4.4 Exchangeable Bases and Cation Exchange Capacity of soils and
geophagic materials……………………………………………………...53
Table 4.5a Modal Composition of Rock Sample from Tokorme 1…………………54
Table 4.5b Modal Composition of Rock Sample from Tokorme 2…………………56
Table 4.5c Modal Composition of Rock Sample from Tokorme 3…………………57
Table 4.5d Modal Composition of Rock Sample from Wuve………………………58
Table 4.6a Modal Composition of the geophagic materials from Tokorme 1………59
Table 4.6b Modal Composition of the geophagic materials from Tokorme 2………61
Table 4.7 Concentration of Heavy metals in the geophagic materials……….……70
Table 4.8a Health Risk Index of Heavy metal in geophagic materials from Tokorme
1…………………………………………………………………………71
Table 4.8b Health Risk Index of Heavy metal in geophagic materials from Tokorme
2…………………………………………………………………………71
Table 4.8c Health Risk Index of Heavy metal in geophagic materials from Tokorme
3………………………………………………………………………….72
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Table 4.8d Health Risk Index of Heavy metal in geophagic materials from
Wuve…………………………………………………………………….72
Table 4.9 Total Heterotroph count, Total Coliform and Faecal Coliform in the
Geophagic materials……………………………………………………74
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LIST OF ABBREVIATIONS
BD Bulk Density
BW Body Weight
CEC Cation Exchange Capacity
DIC Daily Intake of Clay
DIM Daily Intake of Metal
EC Electrical Conductivity
FAO Food and Agriculture Organization
GSS Ghana Statistical Service
HRI Health Risk Index
IAEA International Atomic Energy Agency
LOAEL Lowest Observed Adverse Effect Level
m.a.s.l meters above sea level
MC Metal Concentration
MF Modifying Factor
NOAEL No Observed Adverse Effect Level
RfD Reference Dose
UF Uncertainty Factor
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oC Degree celcius
mL milliliter
mm millimeter
cm centimeter
µm micometer
ηm nanometer
M molarity
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CHAPTER ONE
INTRODUCTION
Geophagia is the deliberate consumption of soil and clay deposits by animals including
man (Wilson, 2003). Geophagy, the practice of eating earthy or soil-like substances, exists
in animals in the wild and also in humans, most often in rural or preindustrial societies, but
also among children and pregnant women (Vermeer, 1971; Abrahams, 2002). The term is
derived from the two Greek words; geo-(earth) and phag-(eat). It is a form of pica which
is an ingestion of non-food substances (Moore and Sears, 1994; Ziegler, 1997). Records on
the practice of eating earthy materials date back as far as 40 BC (Ghorbani, 2008).
Geophagy was also known and recorded in the 13th century in Greek and Roman Ages
(Rose et al., 2000) but the term was first mentioned by the great philosopher, Aristotle
(Mahaney et al., 2000).
The oldest evidence of geophagy practised by man comes from the prehistoric site at the
Kalambo falls on the border between Zambia and Tanzania where Calcium-rich white clay
was found at the site alongside the bones of Homo habilis (Root-Bernstein and Root-
Bernstein, 2000). Geophagy is practised in almost all continents (Brand et al., 2009) by
people of different cultures, races, ages and socio-economic groupings (Hunter, 1993).
However, the practice is more pronounced in children and pregnant women (Abrahams,
2002; Hooda et al., 2004; Gonyea, 2007).
This ancient phenomenon has been reported in several countries across Africa including
Ghana, Kenya, Cameroon, Malawi, Nigeria, South Africa, Tanzania, Togo, Swaziland,
Uganda, DR. Congo, Zambia and Zimbabwe (Mahaney et al., 2000; Dominy et al., 2004;
Ghorbani, 2008). The practice has also been reported in Asia including India, China,
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Philippines and Thailand (Utara, 2002), Australia (Reilly and Henry, 2000), Europe
(Woywodt and Kiss, 2002), and the Americas (Ekosse et al., 2010). Although the practice
occurs in all continents, it is more common in the tropical peasant societies than in the
temperate regions (Abrahams and Parsons, 1996).
Various needs including medicinal, psychological, cultural, physiological as well as
nutritional have been advanced to justify the practice of geophagia (Hunter and Kleine,
1984; Vermeer, 1996; Geissler et al., 1998; Callahan, 2000; Harvey et al., 2000), but many
researchers and non-patrons see the practice as an aberrant behaviour which must be
stopped. Three major hypotheses have been advanced to explain geophagic behaviour in
man, viz: the hunger hypothesis, micronutrient deficiency hypothesis and the protection
hypothesis (Wilson, 2003; Young et al., 2010).
The hunger hypothesis postulates that people consume clay materials because they do not
have anything else to eat (Laufer, 1930). The micronutrient deficiency hypothesis states
that people eat clay material in order to supplement nutrients (Hunter, 1973). The
protection hypothesis posits that geophagia is motivated by an attempt to mitigate harmful
effects of toxins, chemical, or microbes in the body (Young et al., 2010). According to
Starks and Slabach (2012), the negatively charged clay molecules can easily bind to
positively charged toxins in the stomach and gut, preventing the toxin from being absorbed
into the bloodstream.
For people of cultural or tribal sentiment, geophagia is more than just a craving, nutritional,
medicinal or psychological need but an identity one that re-affirms their bonds with mother
earth (Siewe et al, 2000). In Mexico, members of the Roman Catholic Church practise clay
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eating in the Black Christ cult, centered in the shrine of the Santiago de Esquipulas, 241
kilometres northeast of Guatemala City (Hunter, et al., 1984). In the Eastern part of Nigeria,
clay and earthy substances are used by native doctors (Dibias) to cure different diseases
(Izugbara and Emmanuel, 2003).
The Tiv tribe of Nigeria believe that craving for dirt is a sign of pregnancy (Starks and
Slabach, 2012). The Yorubas of Nigeria use clay as one of the active ingredients for the
treatment of dysentery and cholera (Adenuwagun et al., 1979), signifying their medicinal
value. South African urban women believe that ingesting soils enhances their beauty
(Woywodt and Kiss, 2002). Also in Malawi, consuming soil is believed to confirm
pregnancy (Ghorbani, 2008). In the southern parts of the United States of America,
pregnant women ingest soil because they believe it can cure swollen legs, helps babies to
thrive and grow into beautiful children (Tayie, 2004 and Ghorbani, 2008).
According to Reilly and Henry (2000), Woywodt and Kiss (2002), Wilson (2003) and
Tayie (2004), where poverty and hunger are implicated, soil is consumed to suppress
hunger or as a filler, where it acts as a substitute for food. In modern medicine,
pharmaceutical companies have taken advantage of the binding properties of kaolin to
produce kaopectate, a drug used for the treatment of diarrhoea and other digestive ailments
(Starks and Slabach, 2012). Ingestion of clay material has also been associated with bad
health conditions due to the fact that toxic elements are usually ingested along with soil.
Parasitic infestations can also result from soils that have been contaminated with animal
faecal matter.
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According to Wong et al., (1991) toxoplasmosis, roundworm and other parasites have been
reported to be passed to the earth eater in this way. Malnutrition, oral and dental health
problems, intestinal perforation and blockage have been reported by Tayie (2004), Stiegler
(2005) and Gonyea (2007) as other health risks associated with geophagia. The actual
outcome of clay ingestion, either positive or negative, is dependent upon the mineralogy,
geochemistry and physiochemical properties of the material ingested which to a large
extent is influenced by the pedogenetic activities of the soil (Reilly and Henry, 2000; Ngole
et al., 2010). Laufer (1930), reported that earth materials that are normally eaten possess
some desired qualities such as colour, odour, flavour, softness and plasticity.
In Africa, different tribes have different names for geophagic materials. In Nigeria, the Tiv
and the Yoruba tribes call it Eko while the Hausa people call it farin kasa (Vermeer, 1966).
In Kenya, the material is called undongo in Swahili while in Cameroon it is called Calabar
chalk (Ekosse et al., 2008). In Ghana, the Akans call it eshile or hyire, among the Gas it is
called Ayelor and the Krobos call it Nwo, while the Fantes call it eshrew (Tayie et al.,
2013). Among the Ewes of Ghana, it is popularly known as eye, agatawoe or Kpandoko.
In Ghana, geophagia involves ingestion of a creamy-like clay soil (Tayie et al., 2013). The
major source of supply of geophagic clay in Ghana is the Anfoega area in the Volta Region
(Vermeer, 1971). The material is mined from pits, enriched with weathered shales such as
found in the Accraian and the Togo rocks (Vermeer, 1971).
Several studies have been done on geophagia in Ghana (Woywodt and Kiss, 2002, Tayie
et al., 2013). These studies have focused mainly on reasons for the practice (Vermer, 1971;
Hunter, 1973), health implications (Tano-Debrah and Bruce-Baiden, 2010) and nutritional
benefits (Tayie et al., 2013) of the materials. However, the physical, chemical and
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mineralogical properties of the geophagic materials from Anfoega have not been
adequately documented. As reported by Mahaney and Krishnamani (2003), most
geophagic materials in Africa are not properly characterised in terms of their texture, pH,
CEC and EC. This study seeks to provide information on the physical, chemical and
mineralogical characteristics of the geophagic materials from Anfoega. The results of the
study are expected to contribute to knowledge and provide information to the people who
mine, process, market or use it as raw material. Also, nutritionists, public health
practitioners, environmentalists and research institutions can possibly draw information
from the findings of this work.
Thus, the objectives of this study are to:
a. Examine the physical, chemical and mineralogical properties of the geophagic
materials and their overlying rocks and soils from Anfoega.
b. Determine the relationship between the geophagic materials and their overlying
rocks and soils.
c. Assess the potential human health risk associated with the consumption of the
geophagic materials.
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CHAPTER TWO
LITERATURE REVIEW
2.1 Overview
Geophagy is a very complex behaviour which dates from time immemorial. The study of
geophagy cuts across number of academic disciplines such as soil science, anthropology,
medicine, geology, nutrition, geography and ecology (Utara, 2002). Geophagy in humans
is a worldwide habit prevalent in many cultures (Laufer, 1930). The ethnographic accounts
of people and societies indicate that almost every population in their history engaged in
geophagy (Hunter, 1973).
Various aspects of geophagy have been studied such as nutrition (Abrahams et al., 1997),
medicine (Abrahams and Parsons, 1996; Abrahams, 1997), cultural or traditional related
beliefs (Vermeer and Frate, 1979). Other researchers also studied the chemical and physical
characteristics of geophagic soils (Abrahams, 1997; Abrahams and Parsons, 1997;
Aufreiter et al, 1997; Mahaney et al, 2000).
2.2 Definition of Geophagy
Hunter and de Kleine (1984), defined pica as the craving and deliberate consumption of
substances which the consumer does not consider as food for more than one month. It has
also been defined as an ingestion of non-food substances (Moore and Sear, 1994; Ziegler,
1997). The term pica is the Medieval Latin name for the bird called Magpie which has an
indiscriminate eating habit (Solyom, et al., 1991; Moore and sear, 1994). Ambroise Pare′
(1510-1590) a French barber surgeon was the first to use the term as a perverted craving
for substances unfit to be used as food (Danford, 1982). However, inadvertent consumption
of a clod of earth would not be considered pica (Abrahams, 2005).
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Pica in humans has many different subgroups defined by the substance that is ingested.
Some of the commonly described types of pica are eating of soil (geophagy), starch
(amylophagia), ice (pagophagia), and matches (cautopyrelophagia) (Wilson, 2004). Pica
involving other substances including hair (trichophagia), ashes from cigarettes
(stachtophagia), stones or rocks (lithophagia) and wood toothpicks (xylophagia), have also
been reported (Young, et al., 2008). Wilson (2004) also defined geophagy as the deliberate
or purposeful consumption of soil and clay deposites by animals including man. The term
is derived from the two Greek words geo-(earth) and phag-(eat) (Halstead, 1968). Humans
and animals across all continents practise geophagy in a variety of forms making it one of
the most common types of pica (Landa and Feller, 2009). Geophagy is the oldest and the
most reported form of pica.
2.3 Historical Overview
Archeological evidence of calcium rich clay next to the prehistoric remains of Homo
habilis at the Kalambo Falls on the border between Zambia and Tanzania suggests that the
practice of eating earth predates our evolution as a species (Clark, 2001) and this remains
the oldest evidence of geophagy by humans (Root-Bernstein and Root-Bernstein, 2000).
Throughout history, earth eating has been observed by humans and animals (domesticated
and wild), either voluntarily or involuntarily (Krishnamani and Mahaney, 2002). In the
animal kingdom, several terrestrial vertebrates such as birds, reptiles and mammals have
been reported to practise geophagy and this has prompted several research investigations
conducted on them (Krishnamani and Mahaney, 2002). Geophagy in man is as old as
humankind and it is found among the most civilized nations as well as the very primitive
tribes (Laufer, 1930; Abrahams, 2009).
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Geophagy was documented by Hippocrates from 460-380 BC (Rose et al., 2000).
However, the term was first used by the great philosopher Aristotle (Mahaney et al., 2000).
During the period from the sixteenth to eighteenth century, geophagy was regarded as
magical and superstitious which called for the need to have the practice prohibited as
therapy for the practitioners (Halsted, 1968). As early as 40 BC, Terra Sigillataor sacred
earth was introduced among the Greeks to combat sickness and diseases (Hunter and de
Kleine, 1984). Clay obtained from the Greek island of Lemnos by priests was mixed with
goat blood, shaped into pellets or lozenges, dried and stamped with a seal of a goat figure
(Abrahams, 2005).
The ancient Greeks and Romans especially Diocorides and Pliny, believed that the clay
had special medicinal powers (Thompson, 1913). Geophagy is not limited solely to the
Greeks and the Romans. Around AD 1000, earth eating in Europe was identified as a
common habit among children and was thought to be abominable (Abrahams, 2005). The
accounts of Alexander Von Humboldt’s expedition to South America from 1799 to 1804,
revealed a long time practice of earth ingestion among the Ottomac tribe along the Orinoco
valley (Halsted, 1968; Abrahams, 2005). In times of famines and drought, soil was used as
food (Mallory, 1926; Aufreiter et al., 1997), especially in China since 1578 (Will, 1990;
Aufreiter et al., 1997), mixed with flour in Sweden to bake bread (Hunter, 1973) and as a
substitute for butter (Von Humboldt, 1885). Indians similarly add clay to reduce the
astringent effects of bitter raw potatoes (Hunter, 1973). In Guatemala, most of the earth
being eaten is in the form of white clay tablets purchased at Esquipulas (Hunter et al.,
1989). A cake of this kind is sometimes worn as an amulet in a leather case (Laufer, 1930).
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According to Hunter (1973), slaves shipped across the Atlantic during the trans-Atlantic
slave trade transferred the practice of geophagy from Africa to the new world. Slaves in
the plantation ate clay to alleviate gastrointestinal distress, others for reasons of culture and
nutrient supplementation. There were a number of slaves who engaged in excessive soil
consumption only to become ill, avoid work and also to commit suicide in the belief that
their spirit would return to their African homeland (Hunter, 1973). This was a great source
of worry to plantation owners. From Africa to the plantations, the practice subsequently
spread to become almost a world wide phenomenon. In Africa, where geophagy is
predominant, earth from an ancient shrine or from the grave of an ancestor is widely used
in connection with the swearing of oaths and as a medicine (Abrahams, 2005). The Chins
of Burma and the Negroes of Barbados also swallow clay in affirmation of an oath (Laufer,
1930). Earth is widely consumed to control diarrhoea and is also taken as a remedy for
syphilis, especially in the Nile Valley and in Sudan (Anell and Lagercrantz, 1958).
2.4 Aetiology of Geophagy
From antiquity to the present, the aetiology of geophagy has remained elusive and attempts
by various researchers to get enough information from geophagists to ascertain what
triggered the practice have been in futility. According to Laufer (1930), the effects of earth
eating are comparatively easy to recognize but the causes are more difficult to account for.
Even in Africa, where the practice is overt, geophagists are reluctant to give reasons for the
practice (Vermeer, 1987), for fear of stigmatization among laymen and scientists
(Abraham, 2005; Young et al., 2008).
The use of adjectives such as aberrant, abnormal, morbid, odd, primitive, and the like for
the practice puts a distance between the earth-eaters and the information seekers (Vermeer,
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1987; Abraham, 2005). Certain factors like the environment, belief systems, and the mental
constitution of the geophagists influence their desire to indulge in the practice (Abrahams,
2005). Aside these, certain characteristics of the soil inform the choice of the geophagists.
Laufer (1930), noted as a rule, not every kind of earth is eaten, but only those kinds that
have certain appealing qualities such as colour, odour, flavour, softness and plasticity. In
spite of the difficulties in eliciting enough information from geophagists, several research
works have unraveled some causes of geophagy.
2.4.1 Geophagy for Cultural and Religious Purposes
For cultural or more tribal oriented people, geophagia is more than just a craving,
nutritional, medicinal or psychological need. It is an identity, one that re-affirms their
bonds with the mother earth (Siewe et al., 2000). According to Abraham (2009), with the
evolution of culture among human societies, soil was regarded as a source of life and
fertility and symbolic of one’s homeland.
Hunter and de Kleine (1984) reported that in parts of Central America, tablets of white clay
called tierra santa, benditos or “blessed ones” are sold for consumption in connection with
the Black Christ festival. In China, earth-eating was also connected with religious beliefs
among the Arabs and the Mohammedans of India (Laufer, 1930). Hooper and Mann (1906)
reported that dust from the tomb of Prophet Mohammed is an auspicious article, said to be
a cure for every disease. These sacred earths are believed to have special health-giving
properties that are especially associated with pregnancy to satisfy cravings (Abraham and
Parsons, 1996).
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A similar causative explanation is presented by Hunter et al. (1989) for the consumption
of soil in present-day Guatemala and neighboring countries. Holy clay tablets of soil
embossed with religious images are consumed medicinally and during times of pregnancy
and the ingestion always has spiritual connotations. African Slaves in the plantation ate
clay to become part of the earth so that when they die, they would return to their homeland
(Anell and Lagercrantz, 1958). Traditionally, the Ewes of Ghana consume clay called the
“eye” which is prepared into the shape of an egg (Vermeer, 1971). According to him, this
symbolizes longevity, fertility, health and well-being. The egg enters the body and blesses
the woman, making her as bountiful and fertile as the earth.
2.4.2 Geophagy as a Food Supplement
The use of soil as food supplement during times of famine is not restricted to distant times
and has been frequently reported by several researchers (Laufer, 1930). Wilson (2003) and
Ghorbani (2008) reported that poverty, starvation and famine are reasons for consuming
soils. Where poverty or hunger is implicated, soil is consumed to suppress hunger or as
filler, where it acts as a substitute for food (Reilly and Henry, 2000; Woywodt and Kiss,
2002; Wilson, 2003; Tayie, 2004). Schurtz (1893) also reported that the original object of
earth-eating was to silence the hungry stomach for a short while with an indigestible
morsel.
According to Alexander Von Humboldt as reported by Halsted (1968), the Ottomac tribe
along the Orinoco valley ate clay at all times. Mallory (1926) and Aufreiter et al. (1997)
also reported that in the times of famines and drought, soils was used as food especially in
China. On several counts, slaves in the plantation farms ate clay to allay pangs of hunger
and to supplement deficient nutrients in their diet (Haller, 1972) and to alleviate gastric
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pains emanating from hookworm infestation (Hunter, 1973). Even during the recent food
shortage that hit Malawi in 2002, the people engaged in earth eating (Abraham, 2005).
2.4.3 Soil as Medicine or Medicament
The notion that there are links between soils and human health is an ancient one. The
ancient Mesopotamians and Egyptians used clay medicinally as plaster and a cure for
wounds (Starks and Slabach, 2012). In modern medicine, pharmaceutical companies have
taken the advantage of the binding properties of kaolin to produce Kaopectate, a drug used
for the treatment of diarrhoea and other digestive ailments (Starks and Slabach, 2012).
Slaves in the plantation and estates infected with hookworm ate clay to alleviate their
gastric pain (Hunter, 1973). Medically, geophagic clays have been effective in the
treatment of gastrointestinal disorders such as diarrhoea, acid indigestion, nausea, and
stomach aches (Abrahams, 2005) as well as treatment of some types of poisoning. Clays
like kaolin and montmorillonite were also often used in medications (Wiley and Katz,
1998).
2.4.4 Soil as Food Additives and Detoxifier
The uptake of geophagic clay can provide suitable absorptives and detoxicants for the
consumption of phytotoxins, which are typical examples of the Andean tubers (Browman
and Gundersen, 1993). The clays were used to remove toxins or used as condiments or
spices in countries like the Philippines, New Guinea, Costa Rica, Guatemala, the Amazon
and the Orinoco basins of South America and as food during famine (Ross, 1895). In
Ghana, black cotton soils (now called Vertisols) were used to remove the toxin dioscorine,
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from poisonous wild yam Dioscorea dumentorum during times of famine (Abrahams,
2009).
2.4.5 Psychiatric and Physiological Causes of Geophagy
Geophagy, being frequently considered as an aberrant habit, is a recipe for representing it
as a form of mental disorder (Abrahams, 2002). Geophagy as a sign of disorder has been
noted in both adult (Danford and Huber, 1982; Mitchell, 1968) and children (Marchi and
Cohen, 1990). Abrahams (2005) reported that earth eating was frequently observed in
mentally retarded persons, who were unable to discriminate what was or not food.
According to Danford (1982), brain-damaged individuals also exhibit abnormal eating
habits. Geophagy as a physiological disorder is evident in pregnant women who
persistently crave for clay (Tayie, 2004). It has also been reported that soil is consumed by
pregnant women as a tonic and a remedy for indigestion (Abrahams, 2005).
2.5 Health Implications of Geophagy
Clays consumed in most African populations have been shown to contain appreciable
amounts of calcium (Vermeer, 1966; Hunter, 1993) and iron (Wiley and Kartz, 1991).
Studies comparing the micro-nutritional value of geophagic materials and pharmaceutical
supplements for pregnancy showed surprising similarities for several important nutrients
including calcium, magnesium and iron (Lopez et al., 2004). Many studies have treated
geophagy as a behaviour that may provide nutrients otherwise absent in the diet (Young et
al., 2008). Several studies document the medicinal value of geophagy, for example, its
antidiarrheal effects (Vermeer and Ferrell, 1985).
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Appropriate soil material can detoxify toxins found as secondary compounds in plant foods
by absorbing them in the gastrointestinal tract (Johns, 1990; Johns and Duquette, 1991).
Although geophagy has many proven health benefits, it can also have negative health
impacts. Most problems associated with earth eating, however, stem from a general abuse
of the practice. Minerals in the soil can cause excessive tooth wear, erosion of the mucosal
surface of the stomach and intestines and accumulation of soil in the gastrointestinal tract
can cause constipation, abdominal pain, reduced absorption of food, and obstruction and
perforation of the colon (Abrahams, 2005). Excessive intake of earth can cause
obstructions, constipation and other undesirable effects, which will ultimately lead to death
(Laufer, 1930). Ingestion of clay with high cation exchange capacity, such as smectites,
can cause deficiency of nutrients such as Fe, Zn, and K (Oliver, 1997; Abrahams, 2005).
Another probable consequence of geophagy is lead poisoning, with numerous reported case
studies suggesting the co-occurrence of lead poisoning and geophagy (Hackley and Katz-
Jacobson, 2003; Mills, 2007). The study of the prevalence and impacts of geophagy is
becoming increasingly important, as the growing widespread use of agrochemicals in
agriculture is causing high levels of toxic chemicals in soils that may be ingested (Nicholls
and Altieri, 1997).
Geophagy has also been associated with heavy metal toxicity (Calabrese et al., 1997;
Abrahams, 2005; Sing and Sing, 2010) and iodine deficiency disorders and infection by a
number of parasitic soil organisms (Hough, 2007; Sing and Sing, 2010). Parasitic infections
can occasionally occur depending on the regions from which the soil is obtained.
Geophagy, when abused can lead to dehydration, malnutrition and possibly a form of
anorexic suicide (Calabrese et al., 1997; Abrahams, 2005). Mengel (1964) also reported
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that geophagy may cause sluggishness, mental insensibility, severe muscular weakness,
and lassitude. Furthermore, by the principles of osmosis, clay can rob iron and other
nutrients from the body and disrupt equilibrium leading to anemia (Sposito, 1989; Wiley
and Katz, 1998).
2.6 Geophagy: Reports from Ghana
In Ghana, geophagia involves the ingestion of a creamy-white loamy clay soil (Tayie et
al., 2013). The major source of this material in Ghana is Anfoega in the Volta region.
Geophagy in Ghana is an ancient practice that has been sustained for many years (Vermeer,
1971). The practice of eating earthy substances, deliberately in Ghana is a widespread
phenomenon and is not limited to a particular tribe, social classes, sex, age or religion.
However, the practice is more prominent among children and pregnant women (Abraham,
2002; Hooda et al., 2004; Gonyea, 2007). According to Tayie et al., (2013), 28% of women
of productive age in Ghana who practise geophagy consume an average of 70 g of clay
daily. Vermeer (1971), also recorded geophagic rates for men, women and pregnant women
among the Ewes to be 14%, 46% and 63% respectively. He suspected that the actual
percentages may be greater.
In Ghana, geophagists prefer white clay moulded into an egg shape (Vermeer (1971). As
noted by Laufer (1930), not every kind of earth is eaten, but only those kinds that appeal
to consumers through certain qualities such as colour, odour, flavour, softness and
plasticity. According to Vermeer (1971), the annual production of geophagic clay is
approximately 300 tons which are mined from varied environmental settings in Ghana.
Mining of the material is mainly done by men while women perform post mining activities
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ranging from drying to marketing of the materials. The geophagic materials is sold in open
market in different sizes and shapes.
2.7 Geology of the mining site at Anfoega
According to Kesse (1985), Volta region is underlined by the Dahomeyan, the Togo and
the Buem structural units. Anfoega is mainly dominated by the Buem formation which
forms part of the Pan-African mobile belt. The Buem formation consists of thick sequence
of shale, sandstone, calcareous, argillaceous, greywacke and volcanic rocks with
subordinate limestone, tillite, grit and conglomerate (Kesse, 1985, Dapaah-Siakwa and
Gyau-Boakye, 2009) which is formed from the eroded materials of the Togo series
(Dickson et al., 1995; Abass, 2004).
Jones, (1990), noted that the lenticular shape of the sandstones bodies and paucity of
sedimentary structures in the massive sandstones indicate their deposition as alluvial fan
deposits. The rocks underlie an enlongated area on the eastern part of Ghana extending
northeast to the Republic of Togo where sandstone overlie the basal beds of shale and the
conglomerate and tillite overlie the sandstone (Dapaah-Siakwa and Gyau-Boakye, 2009).
Osae, et al (2006), classified the Buem sandstones as quartz arenite and feldspathic arenite.
The rocks of the Buem formation are not metamorphosed but deformation emanate due to
the thrust tectonics with development of imbricated thrust system and duplexes (Jones,
1990). There are large deposits of kaolin in the Anfoega area particularly at Agatanyigbe,
Wuve, Tokorme, Agata and Agatanyigbe (Vermeer, 1971; GSS, 2010). The Bliku hills of
Anfoega Bume is one of the major hills in the area from which this material is mined with
the highest point at about 381 m.a.s.l (GSS, 2010).
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2.8 Vegetation of Anfoega
The vegetation of Anfoega is a mixture of Guinea Savannah Woodland and Semi-
deciduous forest (GSS, 2010). The Savannah woodlands consist of grass with scattered
tress like acacia, bamboo and baobabs. The semi-deciduous forests are found on the slopes
of the Akwapim-Togo-Atakora range with many tree species which are also found in the
high forest zones, such as Antiaristxicaria (Tsentsen), odum, and oil palm (GSS, 2010).
2.9 Chemical Composition of Geophagic Materials
It is important to know the chemical composition of the geophagic clays so as to determine
the health implications of consuming them. Clays are formed by the gradual degradation
of rock; this process is most commonly connected with sedimentary shales, mudstones in
addition to various soils (Willey et al., 1998). The properties of clay are dependent upon
the environment in which they are formed and their weathering conditions (Schulze, 2005).
Clays have different structural and chemical compositions with kaolin, montmorillonite,
halloysite, and allophane as major groupings (Sposito, 1989; Schulze, 2005).
The structure of clay is based on two fundamental units and their crystalline shape resulting
from the organization of silicon-oxygen tetrahedrons in hexagonal networks, giving clay a
large surface area and the ability to bind and exchange metals because of the dense
localization of hydroxyl ions and oxygen in the tetrahedron structures (Sposito, 1989).
Frate (1964) discovered ten elements that were consistently present in three separate clay
samples namely silicon, aluminum, iron, calcium, titanium, potassium, manganese, copper,
cobalt, and chromium. Sposito (1989) also found magnesium, iron, and silicon to be
essential elements in clays. Iron is an important element needed by the body (Sposito
1989). Thus, the presence of iron in clay would be a source of nutrient to the body. The
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concentrations of other elements apart from iron, aluminum, silicon and calcium were
relatively low (Aufreiter et al., 1997).
The properties of clays are controlled mainly by two elements, silicon and aluminum
(Sposito, 1989). He further indicated that silica-aluminum ratio determines the structure of
clays and also their ability to absorb water and organic compounds. Kaolinitic and
montmorillonitic clays are those most frequently consumed by humans (Willey et al.,
1998). The former clay is made up of mostly aluminum and silicon in a 1:1 ratio. Kaolinite
may only absorb organic compounds to their external surface. Conversely,
montmorillonitic clays may absorb cations, water, and organic molecules into the inner
layers (Willey et al., 1998).
2.10 Mineralogical Composition of Geophagic Clays
Clay minerals are secondary minerals derived from chemical alteration of mostly feldspars
and micas (Ekosse et al., 2010). Clay and clay minerals naturally constitute part of the
geological structure of the earth (Mahaney et al., 2000) and are responsible for many of the
soil’s most important and characteristic physical and chemical properties (Schulze, 2005).
Geophagic materials are usually soil sediments that are clay in particle size and contain at
least one clay mineral as mineralogical constituent (Ekosse et al., 2010; Ngole et al., 2010).
Clay minerals are dominantly aluminosilicates made up of tetrahedron and octahedron
sheets constituting a unit cell. Their manner of auto-construction and habit form the unit
cell characterized by layering yielding 1:1 and 2:1 classes of clay minerals (Schulze, 2005).
The 1:1 clay consists of a unit made up of one octahedral and one tetrahedral sheet, with
the apical O2- ions of the tetrahedral sheets being shared with the octahedral sheet. Some
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of the members are kaolinite, halloysite, nacrite and dickite. Kaolinite is a common mineral
in soils and is the most common member of the 1:1 subgroup (Schulze, 2005; Ekosse et al,
2011). It tends to be particularly abundant in more weathered soils such as Ultisols and
Oxisols (Schulze, 2005). The 1:1 layer has little or no permanent charge because of the low
amount of isomorphous substitution. Consequently, cation exchange capacities and surface
areas are typically low.
The 2:1 clay minerals on the other hand, have two tetrahedrally coordinated sheets of
cations both sandwiching an octahedral sheet. This classification has six subgroups viz:
pyrophyllite, micas, vermiculites, talc, smectites, and chlorites (Schulze, 2005). Other clay
minerals that occur in soil clays include palygorskite, sepiolite, zeolites, allophane and
imogolite.
Geophagic clays vary from one region to another with varied mineralogical and chemical
compositions (Ferrell, 2008). Preferences for choice of geophagic materials are determined
by colour, texture, odour and plasticity which are largely influenced by the mineralogical
properties of the geophagic materials. Materials consumed are usually soft, silky, and
powdery (Reilly and Henry, 2000; Nchito et al., 2004; Ngole et al., 2010).
2.11 Biological Properties of Geophagic Clays
The most important properties of clay are its colloidal characteristics, absorption of water,
associated organic materials, and the exchange of cations which influences the health
benefits of geophagy (Sposito, 1989; Ekosse et al., 2008). Clay may be used as an anti-
diarrhoeal medication (Ashenbach, 1987). Diarrhoea occurs when food substances and
liquids travel too quickly through the intestine. This quick progression does not allow the
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body adequate time to absorb water from the digested foods. When kaolin clay is eaten, its
colloidal properties enable it to absorb the excess water found in the body, food and
intestines, thus curing the diarrhoea (Katz and Wiley, 1998). Kaolin clay is a primary
ingredient in many modern antidiarrhoeal medicines such as Turns, Maalox, and Rolaids
hence the name Kaopectate (Ashenbach, 1987).
Clay reduces transit time in the intestines and this allows more water to be absorbed,
resulting in absorption of minerals and vitamins by the body and this may be why many
resort to eating clay during periods of starvation (Aufreiter et al., 1997; Katz and Wiley,
1998). Geophagic material can preserve this delicate electrolyte balance (Aufreiter et al.,
1997). Furthermore, the cation-exchange properties of clay will allow for the unnecessary
minerals in the body to be absorbed by the clay, while the clay can also potentially give up
the minerals and ions the body needs.
Clays have the ability to trap organic and non-organic toxins in their structure (Gonzalez
et al., 2004). While clay traps poisonous and possibly deadly substances, it provides the
body with elements it can use, such as potassium which is required for muscle contraction
(Gonzalez et al., 2004).
Katz and Wiley (1998) proposed that clay consumption throughout the course of pregnancy
confers multiple benefits on the pregnant women. Pregnant women have strong desire for
clay, in all the trimesters which provides calcium an important nutrient critical for the
development of strong foetal skeletons (Katz and Wiley, 1998). Furthermore, clay can form
a protective coatings within the digestive tract which then protects the intestinal mucosa
from being damaged by toxins (Johns, 1990; Johns and Duquette, 1991).
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2.12 Effects of Microorganisms Associated with Geophagy on Humans
Edible soils like any other soils provide a safe dwelling habitat for a host of soil organisms.
These soil organisms derive nutrient, water and energy from the soil in which they habitate
and their activities impact either positively or negatively on the soil. The ubiquitous nature
of microorganisms, predispose earth eaters to a host of pathogenic diseases (Nwoke, 2009).
Geophagic clay may therefore be a source of microbial infection (Tano-Debrah and Bruce-
Baiden, 2010). These pathogenic organisms which may include Sporotrichum schenkii,
Histiplasma capsulatum, Cryptococcus neoformans, Actinomycetes, Clostridium tetenum
and occasionall Escherichia coli and Klebsiellae are usually from feacally contaminated
soils (Aghamirian and Ghiasian, 2009; Bissi-Johnson et al., 2010).
About 3.5 billion parasitic geohelminths exist in the soil and their eggs can be consumed
with ingestion of soil (Abrahams, 2002; Nwoke, 2009) but infection can be significantly
reduced if edible soils are baked (Selinus et al., 2010). Ascariasis and Trichuriasis are
caused by the ingestion of Ascaris lumbricoides and Trichuris trichuira eggs respectively,
while toxocariasis occurs through infection with larvae of Toxocora canis (Nwoke, 2009).
Reports are that chronic liver dosorders or cirrhotic changes may be associated with
ingested soil bacterial and fungi (Selinus et al., 2010). Geophagia has been criticised as
unhygienic and exposing consumers to parasitic infestations (Reilly and Henry, 2000).
Not withstanding the several threats microorganisms pose to geophagists, they also help in
enhancement of bio-activities and maintenance of normal intestinal flora (Tano-Debrah
and Bruce-Baiden, 2010). Microorganisms are the power house for the production of
natural antibiotics (Abrahams, 2002) and also help to biodegrade toxic substances in the
gastrointestinal tract (Ragnarsdottir, 2000).
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2.13 Effects of Heavy Metals Associated with Geophagy on Humans
Heavy metals are notable for their wide environmental dispersion; their tendency to
accumulate in select tissues of the human body; and their overall potential to be toxic even
at relatively minor levels of exposure (Hu, 2002). Metals such as lead and mercury have
no useful role in human physiology and may be toxic even at trace levels of exposure (Hu,
2002). Even metals that are essential may have the potential to turn harmful at very high
levels of exposure (WHO/FAO/IAEA, 1996). These metals are natural components of the
earth's crust and they cannot be degraded or destroyed (Calabrese et al., 1997). Their
existence in the environment arises from both natural and anthropogenic sources (USEPA,
1989).
Geophagy has been associated with heavy metal toxicity (Calabrese et al., 1997; Abrahams
2005; Sing and Sing 2010). Such toxic metals include iron, zinc, copper, manganese,
nickel, aluminium and lead when ingested into the body of consumers (Al-Rmalli et al.,
2010). Excessive ingestion of clay may have serious health repercussion on humans
(Ekosse et al., 2010) due to the fact that the material in addition to being mostly
contaminated with toxic heavy metals and microorganisms, is associated with iodine
deficiency disorders (Hough, 2007; Sing and Sing, 2010; Ekosse et al., 2015). The effects
of heavy metals, especially Pb, As, Cd, Cr and Hg as a result of repeated exposure has been
documented and they include gastro-enteritis, inhibition of haemoglobin formation,
sterility, miscarriage, growth retardation, central nervous system disorder, kidney
dysfunction, hypertension and mental retardation (Amdur, 1991; Ming-HO, 2001; Meharg,
2005).
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Several incidents of diseases caused by the presence of metals in soils have been reported
(USEPA, 1989). These heavy metals are commonly found in the environment and diet and
they enter our bodies via what we consume (WHO/FAO/IAEA, 1996). As trace elements,
some heavy metals like copper, selenium and zinc are essential in promoting various
biochemical and physiological functions of the body (WHO/FAO/IAEA, 1996). However,
at higher concentrations they can lead to poisoning (WHO/FAO/IAEA, 1996).
Heavy metals are dangerous because they tend to bioaccumulate (USEPA, 1989). Heavy
metals including lead, cadmium, mercury, and the metalloid arsenic are persistent in the
environment and have been documented to be potential cause of serious health problems
(USEPA, 1989). Long term exposure to heavy metals can lead to physical, muscular, and
neurological degenerative conditions that may result in diseases such as multiple sclerosis,
Parkinson’s disease, Alzheimer’s disease and muscular dystrophy and sometimes cancer
(Jarup, 2003). Heavy metal toxicity may damage the central nervous system,
cardiovascular system, gastrointestinal system, lungs, kidneys, liver, endocrine glands and
bones (Calabrese et al., 1997). Heavy metals are significant environmental pollutants and
their toxicity is a problem of increasing significance for ecological, evolutionary,
nutritional and environmental reasons (Jaishankar et al., 2014).
2.14 Mining of Geophagic Materials Worldwide
Geophagic materials in general are mined from hills and mountains, river beds, valleys and
termitaria (Reilly and Henry, 2000). Mining of the geophagic clays is achieved through
surface collection, pit extraction (Gosselain and Smith, 2005). In most cases, local miners
use simple digging tools similar to those used by traditional potters of sub-Sahara Africa
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(Gosselain, 1999). No elaborate exploration or prospecting exercise is carried out before
embarking on mining activities (Ekosse et al., 2010).
2.15 Processing of Geophagic Materials
Processing of geophagic materials consist of an array of activities reserved for women with
men offering helping hands when needed (Vermeer, 1971). The geophagic materials are
obtained by local women from pitheads at the mining sites. The materials are dried under
the sun and they become brittle. After drying, the material is pounded in wide mortars or
boards with pestles until very fine particles size is achieved (Reilly and Henry, 2000). An
improvised sieve made from plastics is used to sieve the pounded material. The powder is
then mixed with water and kneaded by hand into different forms of small lozenges or rolls.
In some cases, the women mix the edible clay material with herbs and other plant materials
to spice it (Reilly and Henry, 2000).
After the clay is shaped into small cakes or other shapes, it is baked over fire or dried in
the sun (Reilly and Henry, 2000). The baked clays are ready for distribution to other parts
of the country and other West African countries where they are sold (Hunter, 1973;
Abrahams and Parson, 1996).
2.16 Marketing of Geophagic Materials
The sale of geophagic materials is common in many societies (Gichumbi et al., 2011). The
processing and commercialization of clay tablets, disks, or balls are well documented in
Africa and else where (Hunter, 1993). In African societies, geophagic clay is prepared in
the form of small Lozenges, rolls or balls and sold in local markets (Raily and Henry,
2000). Abraham (1997) reported that in Kampala, Uganda different soils are readily
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available for purchase from street vendors. In Nigeria, large quantities of geophagic
materials are produced and distributed for sale in other West African countries (Hunter,
1973; Ekosse, 2012) in open market with no standardization, advertisement, labeling or
proper packaging (Raily and Henry, 2000).
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CHAPTER THREE
MATERIALS AND METHODS
3.1 Site Selection and Description
The study sites are located at Anfoega in the North Dayi District of the Volta Region of
Ghana (Figure 1a). The area was selected for its long standing history in the production of
the edible clay. In all, four mining sites were selected from a range of hills (the Bliku hills).
Site 1, 2 and 3 were located at Tokorme while site 4 was located at Wuve (Table 1). The
area is underlain by rocks of the Buem structural unit (GSD, 2010). The dominant soils in
the area are Lixisols (Soil Research Institute, 1999).
Table 1: Location of the Study Sites.
Site Location Coordinates Altitude (m.a.s.l) Physiographic Position
1 Tokorme 1 N 060o 52ʹ 499ʹʹ 243.23 Shoulder
E 000o 15ʹ 039ʹʹ
2 Tokorme 2 N 060o 52ʹ 526ʹʹ 232.26 Shoulder
E 000o 16ʹ 015ʹʹ
3 Tokorme 3 N 060o 52ʹ 553ʹʹ 225.86 Shoulder
E 000o 16ʹ 002ʹʹ
4 Wuve N 060o 52ʹ 234ʹʹ 238.05 Shoulder
E 000o 16ʹ 100ʹʹ
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Figure1a: Location of Study Sites.
3.2 Sample Collection and Storage
At each of the four sites, soil, rock and clay samples were taken from pits being mined.
Each pit had a shallow soil (about 60 cm) at the surface underlain by a massive rock of
about 10 metres thick and the white clay deposit below the rock layers (Figure 1b). The
soils were sampled in depth intervals of (0-20 cm, 20-30 cm, 30-40 cm, 40-50 cm and 50-
60 cm). Core samples were also taken within the depth of 0-40 cm for bulk density
determination.
Processed clay samples, were also collected from women involved in the marketing of the
material. All samples were packaged in airtight plastic bags, labelled and then transported
to the laboratory. At the laboratory, the soil and the white clay samples were air dried and
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then gently disaggregated using an agate mortar and pestle. The disaggregated samples
were then passed through a 2.0 mm mesh sieve and repackaged for physical, chemical and
mineralogical analyses.
Samples for microbial analysis were subsampled from the soil samples and the white clay
material. These were put into well labelled sealed plastic bags and placed on iced cubes in
a well cleaned ice chest and transported to the laboratory where they were stored at 5 oC in
a refrigerator until they were analysed. Rock samples taken from all the four sites were
placed in labelled and sealed plastic bags and then transported to the laboratory for
petrographic examination.
Fig. 1b. Vertical cross-section of a pit indicating the position of the geophagic materials.
(Not drawn to scale)
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3.3 Physical Analysis
3.3.1 Bulk Density of the Soil Samples
Metal cylindrical sampling cores of 5 cm diameter and 5 cm height with sharp cutting edges
were pushed into each layer of the soils within 0-40 cm. Excess soil at the top and bottom
faces of the cylinder was carefully trimmed with a flat knife. The core soil samples were
then placed in labelled plastic bags and transported to the laboratory for bulk density
determination. In the laboratory, the core sampler plus soil samples were oven-dried at 105
oC for 24 hours. After 24 hours, the samples were removed from the oven and allowed to
cool in a dessicator. After cooling, the samples were weighed (ie weight of core samples
plus oven dried soil). After weighing, the soil cores were pushed out of the samplers, the
samplers washed and put back into the oven to dry. After drying the samplers and allowing
them to cool in the dessicator, they were weighed. The weights of the samplers were then
subtracted from the weight of the samplers plus soil samples. The radius (r) and height (h)
of the samplers were used to determine the volume of the samplers using the formular,
πr2h. The volume of the samplers was used as the total volume of the soil samples.
The soil bulk density was calculated by using the formula:
ρb = Ms ⁄ Vt
Where ρb is soil bulk density (kg m-3)
MS is the mass of soil solids (kg)
Vt is the total volume of the soil (m3)
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3.3.2 Particle Size Distribution
This is the separation of the mineral part of the soil into various size fractions. After
determining the amount of gravel in each soil sample, the fine earth fraction (˂ 2 mm
fraction) was fractionated according to the sedimentation principle based on Stokes’ Law
which relates the radius of the particles to the velocity of sedimentation. The various size
fractions of the soil were determined using Day’s (1965) modified Bouyoucos hydrometer
method. A 40 g 2.0 mm air-dried soil was weighed into a beaker after which 50 mL of 30%
H2O2 was added to destroy the organic matter in the soil. A 100 mL 5% sodium
hexametaphoshate solution was added to it and the suspension was allowed to stand for 10
minutes and then shaken in a mechanical shaker for 2 hours. The suspension was then
transferred into a graduated cylinder with distilled water and topped up to the 1000 mL
mark. The suspension was allowed to stand to equilibrate at room temperature. The content
of the cylinder was agitated thoroughly using a plunger. Thereafter, the hydrometer and
temperature readings were taken after 5 minutes and 5 hours. Blank hydrometer reading of
5% sodium hexametaphoshate solution, topped up to 1000 mL was taken after 5 minutes
and thereafter 5 hours. After the 5 hour hydrometer reading, the suspension was then
poured directly onto a 50 µm sieve and the effluent discarded. The particles retained on the
50 µm sieve, were thoroughly washed with distilled water, transferred to a moisture can
and oven dried at 105 oC for 24 hours. The dried samples were then weighed to represent
the sand fraction. The particle size distribution was then determined using the following
formular;
(Clay + Silt) % = 5 minute hydrometer reading x100 (1)
Sample mass
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Clay % = 5 hour hydrometer reading x100 (2)
Sample mass
Silt % = (1) - (2) (3)
Sand % = Oven dry mass (g) of particle retained on 50 µm sieve x 100 (4)
Sample mass
The textural class of the soil was then determined using the USDA textural triangle.
3.3.3 Soil Colour
Determination of the colour of both moist and air dried soil samples was done under bright
light condition. A clean spatula was used to fetch individual soil samples and compared
with the colours in the Standard Colour Chart. The Standard Colour Notation of a chip that
was the closest match was recorded as the colour of the soil sample.
3.4 Chemical Analysis
3.4.1 pH (H2O)
For each sample, 10 g of 2.0 mm air-dried soil was weighed into a 50 mL beaker and 20
mL of de-ionized water was added to give a ratio of 1:2. The mixture was then stirred
vigorously for 30 minutes and left to stand for about 1 hour to allow the suspension to settle
and also to equilibrate at room temperature. Standard buffer solutions of pH 4.0 and 7.0;
(Sigma Chemicals, U.S.A) was used to standardized the pH electrometer. The pH was
measured by immersing the electrode into the supernatant and the pH value recorded. For
each soil sample, triplicate determinations on separate sub-samples were carried out and
the mean values taken. The same procedure was carried out on the geophagic clay samples.
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3.4.2 pH (CaCl2)
For each sample, 10 g of 2.0 mm air-dried soil was weighed into 50 mL beaker and 20 mL
of 0.01 M CaCl2 was added to give a ratio of 1:2. The mixture was then stirred vigorously
for 30 minutes and left to stand for about 1 hour to allow the suspension to settle and also
to equilibrate at room temperature. Standard buffer solutions of pH 4.0 and 7.0; (Sigma
Chemicals, U.S.A) was used to standardized the pH electrometer. The pH was measured
by immersing the electrode into supernatant and the pH values recorded. For each soil
sample, triplicate determinations on separate sub-samples were carried out and the mean
value taken. The same procedure was carried out on the geophagic clay samples.
3.4.3 Electrical Conductivity
For each sample, 10 g of 2.0 mm air-dried soil was weighed into 50 mL beaker and 20 mL
of de-ionized water was added to give a ratio of 1:2. The suspension was stirred several
times with a glass rod for 1 hour to dissolve soluble salts after which the suspension was
allowed to settle for 30 minutes. The conductivity electrode was dipped into the supernatant
and the electrical conductivity (EC) measured.
3.4.4 Organic Carbon
Organic carbon was determined using the wet oxidation method of Walkley and Black
(1934). A sample of soil 0.5 g screened through 0.5 mm sieve, was weighed into a 250 mL
Erlenmeyer flask. Then 10 mL of 0.167 M potassium dichromate (K2Cr2O7) solution
followed by 20 mL of concentrated H2SO4 were added to the soil. The flask was swirled to
ensure that the solution was in contact with all the particles of the soil.
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The content of the flask was allowed to stand on an asbestos sheet in the fume cupboard
for 30 minutes for the reaction to complete. Then 200 mL of distilled water and 10 mL of
orthophosphoric acid were added to the content in the flask, swirled to mix the solution
and allowed to cool after which 2.0 mL of barium diphenyalamine sulphonate indicator
was added. The solution was titrated with 0.5 M ferrous ammonium sulphate solution until
the colour changed from orange to a green end-point. The experiment was repeated with
the blank measurement using the same reagents but without soil. For each soil sample,
triplicate determinations of separate sub-samples were carried out and the mean value
taken. The same procedure was carried out on the geophagic clay samples. The percent
organic carbon content of the samples was determined using the formular:
% Organic carbon = M x V1 – V2 x 0.39
Weight of soil (g)
Where, M = Molarity of the FeSO4 solution
0.39 = 3 x 10-3 x 100 x 1.33
V1 = Volume of FeSO4 required for the blank (mL)
V2 = Volume of FeSO4 required for the sample (mL)
3.4.5 Total Nitrogen
The total nitrogen content of the soil and the white clay samples were determined using the
Kjeldahl digestion method (Hesse, 1971). To a sample of 2.0 g of air-dried soil weighed
into a 250 mL Kjeldahl flask, selenium catalyst was added followed by 10 mL of
concentrated H2O2. The mixture was then digested until the digest became clear. The digest
was then allowed to cool and transferred with distilled water into a 50 mL volumetric flask
and made up to the volume.
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A 5.0 mL aliquot of the digest was pipetted into a Markham distillation apparatus and 5.0
mL of 40% NaOH solution was added. Then 5.0 mL of 2% boric acid and few drops of
mixed indicator (0.13 g of methyl red plus 0.666 g of methlylene blue dissolved in 100 mL
of 95% ethanol) were put into a conical flask and placed under the delivery tube of the
condenser in a way that the tip was below the surface of the liquid. The flask was removed
from the distiller, condenser tip rinsed, and the distillate titrated with 0.01 M HCl until
colour changed from green to a purplish end point. The amount of total nitrogen in the soil
was calculated by
% N = (Titre value-Blank) x Molarity of acid x Volume of extract x 14 x 100
Volume of aliquot x Weight of soil (g) x 1000
3.4.6 Cation Exchange Capacity
For each soil and clay sample, 10 g of air-dried samples were weighed into an extraction
bottle and 100 mL of 1.0 M ammonium acetate solution buffered at pH 7.0 was added. The
bottle with its content was placed in the mechanical shaker and shaken for 1 hour. The
content was filtered through a No. 42 Whatman filter paper into a clean empty plastic
bottle. Immediately after that the sample was leached with four 25 mL portions of methanol
to wash off excess ammonium into empty plastic bottles. The ammonium saturated soil
was then leached with four 25 mL portions of 1 M acidified potassium chloride into clean
empty plastic bottles. A 5.0 mL aliquot of the digest was pipetted into a Markham
distillation apparatus and 5.0 mL of 40% NaOH solution added. Then 5.0 mL of 2% boric
acid and few drops of mixed indicator were put into a conical flask and placed under the
delivery tube of the condenser in a way that the tip was below the surface of the liquid. The
flask was removed from the distiller, condenser tip rinsed, and the distillate titrated with
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0.01 M HCl until colour changed from green to a purplish end point. The cation exchange
capacity in cmolc kg-1 soil was then calculated from the number of moles of HCl consumed
in the back titration reaction.
3.4.7 Determination of Exchangeable Bases
For each soil and white clay, 10 g of air-dried samples were weighed into an extraction
bottle and 100 mL of 1.0 M ammonium acetate solution buffered at pH 7.0 was added. The
bottle with its content was placed in the mechanical shaker and shaken for 1 hour. The
content was filtered through a No. 42 Whatman filter paper into a clean empty plastic
bottle. The filtered solution was used for the determination of Ca, Mg, K, and Na using
atomic absorption spectrophotometer.
3.4.8 Determination of Total Phosphorus
For each soil and white clay, 2.0 g sample screened through 0.5 mm sieve was weighed
into a 250 mL Erlenmeyer flask. Then 10 mL of concentrated HNO3 and 15 mL of 60%
HClO4 were added and the mixture was then digested till the digest became colourless and
dense white fumes of HClO4 ceased. The digest was allowed to cool and later diluted with
distilled water. The digest was filtered through a No. 42 Whatman filter paper into a 100
mL volumetric flask and made up to the volume. Thereafter, a 5.0 mL aliquot of the digest
was pipetted into 50 mL volumetric flask. The pH was adjusted by adding few drops of P-
nitrophenol indicator and few drops of 4 M NH4OH until the sample solution turned
yellow. Then 8.0 mL of a solution containing concentrated sulphuric acid, ammonium
molybdate, potassium antimony tartrate, and ascorbic acid were added and made up to the
volume with distilled water. The solution was mixed thoroughly and made to stand until
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blue colour developed. Standards and sample absorbance were measured at a wavelength
of 712 nm.
3.4.9 Available Phosphorus
3.4.9.1 Olsen’s Extraction Procedure
The available P content of the soils was determined following the method of Olsen et al.,
(1954), for samples that had alkaline pH. To 5.0 g of air-dried soil in an extraction bottle,
50 mL of sodium carbonate solution was added. The bottle was corked and shaken for 30
minutes after which the suspension was filtered through Whatman No. 42 filter paper. An
aliquot of the filtrate was pipetted into a test tube and 1.0 mL of 1.5 M H2SO4 added in a
dropwise manner to decolourise the solution by settling the organic matter in solution. The
solution was left in a refrigerator for some time to cool after which it was centrifuged at
5000 rpm for 15 minutes and the content decanted. An aliquot was pipetted for colour
development and intensity readings. The absorbance for standards and samples were
measured at a wavelength of 712 nm.
3.4.9.2 Bray 1 Method
The Bray and Kurtz (1945) method was used to determine the available P content of soils
with acidic pH. To 5.0 g of air-dried soil weighed into an extraction bottle 50 mL of the
extractant (0.03 M NH4F in 0.025 M HCl) was added making a 1:10 soil-to-solution ratio.
The suspension was shaken vigorously for exactly 2 minutes on the mechanical shaker.
The content was filtered through Whatman No. 42 filter paper after which a 5.0 mL aliquot
was pipetted for colour development. The absorbance for the standards and samples were
measured at a wavelength of 712 nm.
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3.5 Mineralogical Analysis
3.5.1 Thin Section Preparation and Petrographic Examination of Rock Samples
Thin sections of the rock samples were prepared. The rocks were first cleaned to prevent
contamination. Each rock sample was carefully examined and cut with a diamond edge
electrical saw to obtain representative thin slabs with flat surfaces. After that the grinding
machine and corundum dust (silicon carbide 220) were used to smoothen and flatten the
surface of the sliced rocks. With the help of a grinding machine and silicon carbide 600,
the thin slab was further polished to obtain smooth surfaces. The frosted side of the slide
(glass) was then attached to the side of the chip that was grounded down to ensure constant
thickness of epoxy (Canada Balsam) spread across the section. It was later pressed to
escape trapped air after which it was heated on a hot plate. After mounting the rock chip
on the glass slide, the slab was ground to the preferred thickness. The thickness and colour
of the minerals, particularly of quartz were timely observed under the microscope at each
stage of the grinding until the grains showed a yellowish-grey interference colour when
oriented parallel with the optical axis indicating the thickness was up to standard and
therefore the grinding was stopped at this stage. A cover slip was then added to protect the
section from damage and to increase the clarity observed in the microscope before the final
polishing was done. This was heated again on the hot plate, pressed and later washed with
kerosene. The thin section was examined petrographically using a polarized light
microscope. Non-solid rock samples were boiled or impregnated and hardened with
Canada Balsam.
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3.5.2 Fractionation of Samples
The soil samples were pretreated with 30% H2O2 to remove organic matter. Then, about 40
g of fine earth fraction was weighed into 1 litre beaker after which 20 mL of water was
added. Then, 20 mL of H2O2 was added slowly to the soil sample to avoid excessive
frothing, stirred and the beaker covered with watch-glass to prevent spattering. Strong or
excessive frothing was prevented by adding a few drops of ethanol and allowing the sample
to stand overnight. The next day, the beaker was placed on a water bath at 80 oC and 30%
H2O2 was added in 5-10 mL increments until decomposition of organic matter was
completed.
When the supernatant was clear, soil adhering to the watch glass was washed into the
beaker and water was added and made up to 300 mL. The beaker containing the mixture
was placed on a hot plate and carefully boiled for 1 hour to remove any remaining H2O2.
The beaker was removed from the hot plate and allowed to cool. A 50 mL 5% sodium
hexametaphoshate solution was added to it and the suspension was allowed to stand for 10
minutes and then shaken in a mechanical shaker for 15 minutes. The suspension was then
transferred into a graduated cylinder with distilled water and topped up to the 1000 mL
mark. The suspension was allowed to stand for 5 hours to equilibrate. Then 50 mL of the
clay suspension was pipetted from 20 cm depth into a 100 mL beaker which was carefully
air-dried and powder obtained. The geophagic clay materials were not subjected to the
above methodology because they were found to contain very minimal organic carbon.
3.5.3 Potassium Saturation of Exchange Complexes
To saturate the soil clay samples and geophagic clay with K, 25 mg of air-dried sample
was weighed into a 15 mL centrifuge tube. Then 10 mL 1 M KCl was added to the clay
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sample and centrifuged at 1500 rpm for 5 minutes after which the supernatant solution was
discarded. This was repeated four times to complete the saturation of the clay with K. The
excess salt was removed from the sample by washing once with 50% methanol, then with
95% methanol, and finally with 95% acetone until the decantate gave a negative test for
chloride with AgNO3.
3.5.4 Sample Preparation
An oriented-aggregate specimen was formed directly from the K-saturated clay. The
sample was mixed with deionized water and the suspension was pipetted and carefully
transferred onto a glass slide placed on a level surface. The suspension was then allowed
to dry on the slide pending further analysis.
3.5.5 X-Ray diffraction
The K-saturated room temperature samples (K-25) were subjected to X-Ray analysis.
Thereafter, the same slides were heated to 350 oC (K-350) for 2 hours and then subjected
to X-ray analysis. Then finally, the 350 oC heated samples were heated to 550o C (K-550)
for 2 hours and then X-ray analysed.
3.6 Heavy Metal Analysis
A 2.0 g of air dried geophagic materials screened through 0.5 mm sieve was weighed into
a 250 mL Erlenmeyer flask. Then 10 mL of concentrated HNO3 and 15 mL of 60% HClO4
were added and the mixture was then digested till the digest became colourless and the
dense white fumes of HClO4 ceased. The digest was allowed to cool to room temperature
and later diluted to 10 mL using distilled water and left to settle overnight. The supernatant
was filtered through a No. 42 Whatman filter paper prior to analysis using AAS (Perkin
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Elmer). The concentration of metals in each sample was recorded and their means
determined. The dose response assessment was computed following guidelines set by
(USEPA, 2002). A published Reference Dose (RfD) values of the heavy metals for humans
was used to calculate the health risk index (HRI) taking into consideration the daily intake
of the clay and the average body weight of the consumer. The RfD is an estimation of a
daily exposure to the human population that is likely to be without an appreciable risk of
adverse health effect over a lifetime (USEPA, 2002). This is based on the assumption that
there is a threshold for certain toxic effect. The RfD expressed in units of mg kg-1 day-1
was computed using the formular of USEPA, (2002)
1. RfD (mg/kg-day) = NOAEL or LOAEL
UF X MF
Where:
NOAEL = No Observed Adverse Effect Level (mg kg-1 day-1) or
LOAEL = Lowest Observed Adverse Effect Levels (mg kg-1 day-1)
UF = Uncertainty factor
MF = Modifying factor
2. The HRI was calculated using the formular of Cui et al. (2004) and adopting a 70
g clay intake per day of Ghanaian women by reproductive age reported by Tayie et
al. (2013).
HRI = Daily Intake of Metal (DIM)
RfD
3. The DIM was calculated using the following formular
DIM = MC X DIC
BW
Where
MC = Metal Concentration
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DIC = Daily Intake of Clay
BW = Body Weight 60 kg for consumers (WHO/IAEA, 2006)
The HRI of individual metals were compared with an index of 1 beyond which there is a
potential health effect (Huang et al. 2008).
3.7 Microbial Analysis of the Geophagic Materials
About 10 g of geophagic materials was weighed into medicinal bottle containing 90 mL of
ringer solution. The sample was then vortexed for 30 minutes after which a 1.0 mL of the
90 mL diluent was transferred into a test tube containing 9.0 mL of the ringer solution.
This was serially done to 10-6 with the aid of micropipette. Thereafter, 1.0 mL of the 10-6
diluent was asceptically transferred unto sterile petri–dish and mixed thoroughly. The plate
was allowed to set and incubated at between 35 – 37 oC for between 18-24 hours. After the
incubation period, the colonies were counted to determine how many microorganisms were
present in original samples. Plates with more than 30 of these colonies but less than 300
were counted and their Cfu calculated using the following formular:
B = N/D
B = Number of Bacteria
N = Number of Colonies Counted on a plate
D = Dilution factor
3.8 Questionnaire to solicit information on the ingestion of the geophagic
materials from Anfoega
Structured questionnaires were administered to the miners, sellers and consumers of the
geophagic materials as well as personnel at health facilities in the catchment area of the
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sites. Questionnaires were conducted in Ewe and English languages. The objective of the
exercise was to find out the impact of clay mininig on the environment, on the people and
the health implications of consuming the geophagic materials. The questionnaires written
in English language were translated to the miners, consumers and the women involved in
processing the clay into the Ewe language. Their responses were however, recorded in
English language. In the case of the health personnel, the interviews were conducted in
English language. In all, four (4) miners, ten (10) women, sixteen (16) consumers and three
(3) health facilities were interviewed according to the questionnaires (see Appendix 1).
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CHAPTER FOUR
RESULTS
4.1 Morphological Properties of the Soils
The morphological properties of the soils are presented in Table 4.1. Under moist
condition, the colour of Tokorme 1 ranged from brownish black (10YR3/2) in the surface
layer to dull reddish brown (5YR5/4) in the bottom layer. In Tokorme 2, the colour (moist)
ranged from brown (7.5YR4/4) in surface layer to bright reddish brown (5YR5/6) in the
bottom layer. In Tokorme 3, the colour (moist) ranged from brown (7.5YR4/4) in the
surface layer to bright reddish brown (5YR5/6) in the bottom layer. In Wuve, the colour
(moist) ranged from dark reddish brown (5YR3/2) in the surface layer to dull orange
(2.5YR6/4) in the bottom layer. Under dry condition, the colour of Tokorme1 ranged from
greyish brown (7.5YR4/2) in the surface layer to dull orange (5YR7/3) in the bottom layer.
In Tokorme 2, the colour (dry) ranged from dull orange (7.5YR6/4) in surface layer to dull
orange (7.5YR6/4) in the bottom layer. In Tokorme 3, the colour (dry) ranged from dull
reddish brown (5YR5/3) in the surface layer to orange (5YR7/6) in the bottom layer. In
Wuve, the colour (dry) ranged from dull orange (5YR6/3) in the surface layer to dull orange
(5YR7/4) in the bottom layer.
The texture of Tokorme 1 and Wuve were sandy clay loam in all layers. The texture of
Tokorme 2 was clay in the surface and subsurface layers but changed to sandy clay loam
at the bottom layers. In Tokorme 3, the texture was clay in the surface and subsurface layers
but it changed to sandy clay loam in the bottom layer.
The soils from the four sites were well drained. The soils from Tokorme 1 had granular to
subangular blocky structure in the surface and subsurface layer but changed to granular in
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the bottom layers. The soil from Tokorme 2 had a granular to subangular blocky structure
in the surface layer but changed to subangular blocky in the subsurface layer and the bottom
layers. The soils from Tokorme 3 and Wuve had granular structure in the surface layers
but changed to subangular blocky in the subsurface layers and the bottom layers.
The soil from Tokorme 1 was generally non-sticky, friable and slightly hard in consistence
under wet, moist and dry conditions respectively. The consistence of Tokorme 2 was sticky
(wet), firm (moist) and very hard (dry). Tokorme 3 was non sticky (wet), friable (moist)
and slightly hard (dry) in consistence. The consistence of Wuve, was slightly sticky (wet),
friable (moist) and hard (dry). The sizes and quantity of roots the soils contained reduced
with soil depth.
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Table 4.1. Morphological Properties of the Soils.
Depth Colour Colour Structure1 Consistence2 Roots3
(cm) (moist) (dry) wet moist dry
Tokorme 1
0-20 10YR3/2 7.5YR4/2 gr-sbk ss fr sh mm, mf
20-30 10YR3/3 10YR4/2 gr-sbk ns fr sh ff
30-40 7.5YR3/2 10YR 5/2 gr ss fr sh ff
40-50 5 YR 5/4 5 YR 8/2 gr ns fr sh ff
50-60 5 YR 5/4 5 YR 7/3 gr ns fr sh vff
Tokorme 2
0-20 7.5YR4/4 7.5YR6/4 gr-sbk ss fi h mm, mf,mvf
20-30 5 YR 4/4 5 YR 6/4 sbk s fi vh mm, mf
30-40 5 YR 4/6 5 YR 6/4 sbk s fi vh fm
40-50 5 YR 4/6 5 YR 6/4 sbk s fi vh vff
50-60 5 YR 5/6 7.5YR6/4 sbk s fi vh vff
Tokorme 3
0-20 7.5YR4/4 5 YR 5/3 gr ss fr sh mm, mf, mvf
20-30 5 YR 5/6 7.5YR6/4 sbk ns fr sh vff
30-40 7.5YR5/4 7.5YR6/4 sbk ss fr sh vf
40-50 5 YR 4/6 5 YR 6/4 sbk ns fr sh vf
50-60 5 YR 5/6 5 YR 7/6 sbk ns fr sh ND
Wuve
0-20 5 YR 3/2 5 YR 6/3 gr ns fr h mm, mf, mvf
20-30 5 YR 4/4 5 YR 6/3 sbk ss fr h vff
30-40 2.5YR6/4 5 YR 6/4 sbk ss fr h vff
40-50 2.5YR6/4 5 YR 7/4 sbk ss fr h ND
50-60 2.5YR6/4 5 YR 7/4 sbk ss fr h ND
1gr = granular, sbk = subangular blocky, 2s = sticky, ss = slightly sticky, ns = non-sticky,
fr = friable, fi = firm, h = hard, sh = slightly hard, vh = very hard, 3ff = few fine, mm =
many medium, mf = many fine, mvf = many very fine, vff =very few fine, ND = Not
determined.
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4.2 Physical Properties
4.2.1 Particle Size Distribution and Texture
The sand content of Tokorme 1 ranged from 64.7 to 66.7% (Table 4.2). The amounts
decreased slightly with depth. The silt content of Tokorme 1 ranged from 7.6 to 10.3% and
the clay content ranged from 23.0 to 27.7%. In Tokorme 2, the amount of sand ranged from
33.2 to 51.2%. The silt content of Tokorme 2 ranged from 15.2 to 17.2% and the clay
content ranged from 33.6 to 49.6%. The sand content of Tokorme 3 ranged from 25.5 to
57.2%. The silt content of Tokorme 3 ranged from 7.6 to 12.7% and the clay content ranged
from 34.1 to 61.5%. The sand content of Wuve ranged from 64.3 to 69.5%, the silt from
10.1 to 10.6% and the clay from 20.1 to 25.5%. The clay content of the geophagic materials
were 51.4% in the samples from Tokorme 1, 63.5% in Tokorme 2, 68.8% in Tokorme 3
and 66.8% from Wuve. The silt fraction ranged from 28.66% to 45.71% in all four samples
with sand recording less than 5%. The clay fraction clearly dominated in the geophagic
materials.
4.2.2 Bulk Density
The bulk density (BD) of Tokorme 1 ranged from 0.83 to 1.09 Mg m-3 and from 1.29 to
1.45 Mg m-3 in Tokorme 2 and increased with depth. The bulk density of Tokorme 3 ranged
from 0.98 to 1.10 Mg m-3 and from 1.11 to 1.51 Mg m-3 in Wuve and increased with depth.
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Table 4.2. Selected Physical Properties of the soils.
Depth
Particle Size Distribution Texture1 Bulk Density
(%)
(cm) Sand Silt Clay (Mg m-3)
Tokorme 1
0-20 66.7 10.3 23.0 SCL 0.93
20-30 66.8 7.7 25.5 SCL 0.83
30-40 66.2 7.7 26.0 SCL 1.09
40-50 64.7 10.1 25.2 SCL ND
50-60 64.7 7.6 27.7 SCL ND
Tokorme 2
0-20 33.2 17.2 49.6 C 1.29
20-30 41.3 15.3 43.4 C 1.38
30-40 51.2 15.2 33.6 SCL 1.45
40-50 50.4 15.3 34.3 SCL ND
50-60 46.4 15.4 38.2 SC ND
Tokorme 3
0-20 25.5 12.7 60.9 C 0.98
20-30 30.9 7.6 61.5 C 1.1
30-40 31.2 7.6 61.2 C 1.1
40-50 32.1 9.7 58.2 C ND
50-60 57.2 8.7 34.1 SCL ND
Wuve
0-20 64.3 10.2 25.5 SCL 1.11
20-30 64.7 10.1 25.2 SCL 1.26
30-40 67.3 12.6 20.1 SCL 1.51
40-50 69.5 10.4 20.1 SCL ND
50-60 69.3 10.6 20.1 SCL ND
Geophagic Materials
Tokorme 1 2.9 45.7 51.4 SiC ND
Tokorme 2 4.9 31.6 63.5 C ND
Tokorme 3 2.6 28.6 68.8 C ND
Wuve 4.2 29.0 66.8 C ND
1: S = sand, C = clay, SCL = sandy clay loam, SiC = silty clay
ND = Not determined.
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4.3 Chemical Properties
4.3.1 pH Water and pH Calcium Chloride of the Soils and the Geophagic
Materials
The soils from Tokorme 1 had alkaline pH which ranged from 7.06 to 7.20 (Table 4.3).
The soil from Tokorme 2 was slightly acidic (pH 6.48) in the surface layer but strongly
acidic in the subsurface to bottom layers (pH 4.28 to 4.97). Below the surface, the pH
decreased gradually with depth. The pH (H2O) of Tokorme 3 showed a trend that was the
reverse of that of Tokorme 2. The soil was slightly acidic in the surface and subsurface
layers but strongly acidic in the bottom layer. The pH (H2O) of the Wuve soil ranged from
slightly acidic (pH 6.71) in the surface layer to moderately acidic (pH 6.05) in the bottom
layer. Apart from Tokorme 1, the pH of the soils decreased with depth. The pH (H2O) of
the geophagic materials was strongly acidic (pH 3.5 to 4.70).
The pH (CaCl2) of the soil from Tokorme 1 was moderately acidic which ranged from pH
(5.94 to 6.22) (Table 4.3). The pH (CaCl2) of Tokorme 2 was moderately acidic at the
surface (pH 5.12) but strongly acidic in the subsurface to bottom layer (pH 3.52 to 3.64).
The soil from Tokorme 3 was moderately to slightly acidic (pH 5.42 to 6.39) in the surface
to the subsurface soils but strongly acidic in the bottom soils (pH 4.61 to 4.93). The pH
(CaCl2) of the Wuve soil was moderately acidic from the surface soil to the bottom soils
(pH 5.53-6.10). Apart from Wuve, the pH (CaCl2) of the soils tended to decrease with
depth. The pH (CaCl2) of the geophagic materials was strongly acidic (pH 3.34 to 3.60).
4.3.2 Electrical Conductivity
Generally, the electrical conductivity of the soils decreased with depth (Table 4.3). The
values ranged from 0.07 to 0.16 dS m-1 (Tokorme 1), 0.07 to 0.12 dS m-1 in Tokorme 2,
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0.07 to 0.15 dS m-1 in Tokorme 3 and 0.05 to 0.13 dS m-1 in Wuve. The electrical
conductivity of the geophagic materials was about two to four folds higher than that of the
soils. It ranged from 0.6 dS m-1 in Tokorme 1 to 0.22 dS m-1 in Tokorme 2.
4.3.3 Total Nitrogen Content of the Soils and Associated Geophagic Materials
The total nitrogen content of the soils and their associated geophagic materials was very
low (Table 4.3). In all the soils, total nitrogen content generally decreased with depth.
However, Tokorme 1 and Tokorme 2, contained relatively higher amounts. Generally, the
geophagic materials, with the exception of Tokorme 3, contained lower amounts of total N
in the surface and subsurface soils than was found in their associated soils.
4.3.4 Organic Carbon Content of the Soils and the geophagic materials
With the exception of Tokorme 3, the organic carbon content of the surface layers of the
soils was moderately high, particularly in Tokorme 1 (3.37%) (Table 4.3). Soils from the
20-30 cm and 30-40 cm at Tokorme 1 contained >1.0% organic carbon. The organic carbon
content of all the soils decreased sharply from the surface soil to the subsurface soils, and
generally decreased with depth. The geophagic materials contained much lower amounts
of organic carbon which ranged from 0.07 to 0.10%.
4.3.5 Phosphorus Content (Total and Available) of the Soils and the Geophagic
Materials
The available P content of the soils was low (< 10.0 mg kg-1) and tended to decrease with
depth (Table 4.3). The geophagic materials also contained small amounts of available P
(5.36 to 11.52 mg kg-1) which were generally comparable to the levels in the soils. The
total P content of the soils was very low (< 50.0 mg kg-1). The geophagic materials also
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contained very low amounts of total P (< 80.0 mg kg-1) but the levels were relatively higher
than those found in the soils. The total P content in the geophagic materials of Tokorme 1
was about twice the levels in the geophagic materials from the other sites.
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Table 4.3 Selected Chemical Properties of the Soils and Geophagic Materials.
Depth pH(H2O) pH(CaCl2) E.C1 Total N2 O.C3 Available P4 Total P
(cm) (dS m-1) (%) (%) (mg kg-1) (mg kg-1)
Tokorme1
0-20 7.20 6.22 0.16 0.44 3.37 7.06 31.30
20-30 7.16 6.15 0.14 0.39 1.95 3.50 31.80
30-40 7.06 6.04 0.10 0.37 1.05 6.20 28.35
40-50 7.12 6.00 0.07 0.32 0.63 3.68 48.15
50-60 7.07 5.96 0.07 0.23 0.59 5.10 50.80
Tokorme 2
0-20 6.48 5.12 0.12 0.42 1.80 8.48 48.55
20-30 4.97 3.64 0.07 0.33 0.44 9.62 41.40
30-40 4.95 3.62 0.07 0.27 0.59 6.00 43.05
40-50 4.90 3.52 0.07 0.12 0.33 3.98 46.85
50-60 4.28 3.60 0.09 0.14 0.78 5.10 48.60
Tokorme 3
0-20 6.62 6.39 0.15 0.18 0.51 9.26 43.25
20-30 6.58 5.66 0.08 0.09 0.28 7.38 36.35
30-40 6.33 5.42 0.09 0.10 0.45 4.42 31.85
40-50 6.22 4.93 0.07 0.09 0.27 4.52 31.25
50-60 4.67 4.61 0.08 0.08 0.29 2.60 36.95
Wuve
0-20 6.71 6.10 0.13 0.26 1.97 7.34 40.40
20-30 6.55 5.53 0.07 0.11 0.51 6.12 22.55
30-40 6.48 5.62 0.06 0.07 0.16 3.12 23.25
40-50 6.52 5.57 0.05 0.04 0.16 2.96 18.20
50-60 6.05 5.69 0.05 0.05 0.20 3.84 23.55
Geophagic Materials
Tokorme 1 3.58 3.34 0.60 0.23 0.07 11.52 67.90
Tokorme 2 4.27 3.57 0.22 0.06 0.08 5.36 46.85
Tokorme 3 4.28 3.48 0.20 0.23 0.10 5.82 60.50
Wuve 4.70 3.60 0.12 0.20 0.07 6.00 51.35
1E.C = electrical conduction, 2N = nitrogen, 3O.C = organic carbon, 4P = phosphorus
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4.3.6 Exchangeable Bases and Cation Exchange Capacity of the Soils and
Geophagic Materials
The four soil samples contained very low levels of exchangeaable bases (Table 4.4). Their
exchangeable Ca content ranged from 0.057 to 0.829 cmolc kg-1. The exchangeable Mg
content of the soils ranged from 0.072 to 0.193 cmolc kg-1. The exchangeable K content
ranged from 0.016 to 0.129 cmolc kg-1 and Na from 0.0001 to 0.0031 cmolc kg-1. The
geophagic materials from the four sites had comparably low levels of exchangeable bases.
The CEC of the soils ranged from 5.29 to 22.56 cmolc kg-1. Generally, the soil from Wuve
had the lowest CEC. The CEC of the geophagic materials was relatively higher (18.00 to
23.18 cmolc kg-1) than that of the soil samples.
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Table 4.4. Exchangeable Bases and Cation Exchange Capacity of the Soils and Geophagic
Materials.
Depth Ca Mg K Na CEC
(cm) (cmolc kg-1)
Tokorme 1
0-20 0.829 0.168 0.054 0.0028 13.79
20-30 0.548 0.153 0.052 0.0020 19.44
30-40 0.292 0.159 0.035 0.0015 10.69
40-50 0.117 0.117 0.016 0.0001 10.28
50-60 0.173 0.128 0.023 0.0008 8.89
Tokorme 2
0-20 0.237 0.186 0.071 0.0007 17.17
20-30 0.468 0.130 0.034 0.0005 12.57
30-40 0.560 0.177 0.053 0.0017 16.88
40-50 0.434 0.181 0.042 0.0018 16.42
50-60 0.068 0.193 0.042 0.0010 13.04
Tokorme 3
0-20 0.264 0.164 0.107 0.0010 15.81
20-30 0.069 0.150 0.093 0.0009 11.37
30-40 0.060 0.158 0.108 0.0003 13.80
40-50 0.059 0.168 0.129 0.0010 13.46
50-60 0.075 0.158 0.111 nd 22.56
Wuve
0-20 0.474 0.181 0.069 0.0031 14.94
20-30 0.080 0.108 0.041 0.0009 10.85
30-40 0.596 0.094 0.025 0.0009 6.08
40-50 0.215 0.072 0.030 0.0025 5.29
50-60 0.057 0.106 0.027 0.0005 6.59
Geophagic Materials
Tokorme 1 0.020 0.024 0.121 0.0028 20.19
Tokorme 2 0.048 0.170 0.048 0.0040 23.18
Tokorme 3 0.040 0.068 0.043 0.0023 18.00
Wuve 0.092 0.106 0.043 0.0019 21.92
nd = not detected.
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4.4 Mineralogical Composition of the Rocks, Geophagic Materials and Soils
4.4.1 Thin Section Petrography of Rock Samples
Visual examination and thin section analysis of the rock samples from the pits at the study
sites were done. The visual examination revealed characteristics namely grain sizes,
mineral composition as well as texture of the rocks encountered in the study area. Apart
from the grain size, texture and mineralogical composition, the thin sections also revealed
petrographic features namely structures and deformations of the rock samples. Modal
estimation was done by the visual counting of their individual mineral grains present. The
major rock types encountered in all the study sites were mainly sandstones.
4.4.1.1 Thin Section of Rock Sample from Tokorme 1
This rock was grey, but reddish-brown on the weathered surface (Figure 2a). The rock was
a clastic with fine to medium grains of feldspar, quartz and other clastic materials.
Microscopically, the rock is composed of rounded to sub-rounded grains which were
poorly sorted. It was composed of quartz, minor feldspar, sericite and other rock fragments
which were cemented by iron oxide. The rock was very rich in quartz some of which
exhibited undulose extinction. The feldspars were significantly altered into sericite. The
rock fragments contained rounded fine grains of quartz.
Table 4.5a. Modal Composition of Rock Sample from Tokorme 1.
Minerals Volume (%) Characteristics
Quartz 86 Rounded to sub-rounded, mostly undulose
Feldspar 9 Mostly altered into sericite
Sericite 5 Secondary products of altered feldspar
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Figure 2a. Sandstone showing sub-rounded to rounded grains that were cemented by iron
oxide in the rock sample from Tokorme 1.
4.4.1.2 Thin Section of Rock Samples from Tokorme 2
The rock was grey, thinly bedded and medium to coarse grained (Figure 2b). It was poorly
sorted and composed of sub-rounded to rounded feldspar and quartz with other rock
fragments. The rock felt gritty to touch and did not fizz with dilute HCl.
Petrographically, the rock was fine to medium grained with rounded to sub-rounded and
poorly sorted grains. It was composed of mainly quartz, feldspars, and other rock
fragments, which had been cemented by iron (Fe) oxide. Quartz exhibited undulose
extinction which indicated deformation. The feldspars were completely or partially altered
into sericite, however, with preserved pseudomorphs.
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Table 4.5b. Modal Composition of Rock Sample from Tokorme 2.
Minerals Volume (%) Characteristics
Quartz 85 Rounded to sub-rounded, mostly undulose
Feldspar 10 Significantly altered into sericite
Sericite 5 Secondary products of altered feldspar
Figure 2b. Sub-rounded to rounded grains cemented by iron oxide in rock sample from
Tokorme 2.
4.4.1.3 Thin Section of Rock Samples from Tokorme 3
The rock was grey, thinly bedded and medium to coarse grained. The rock felt gritty to
touch and did not fizz with dilute HCl. The rock was fine to medium grained, rounded to
sub-rounded, and poorly sorted. It was composed of mainly quartz, feldspars, and other
rock fragments, which were cemented by iron (Fe) oxide. Quartz exhibited undulose
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extinction which indicated deformation. The feldspars were completely or partially altered
into sericite, however, with preserved pseudomorphs.
Table 4.5c. Modal Composition of Rock Sample from Tokorme 3.
Minerals Volume (%) Characteristics
Quartz 84 Rounded to sub-rounded, mostly undulose
Feldspar 9 Significantly altered into sericite
Sericite 7 Secondary products of altered feldspar
Figure 2c. Sutured and recrystallised quartz in rock sample from Tokorme 3.
4.4.1.4 Thin Section of Rock Samples from Wuve
This rock was grey but reddish-brown on weathered surface (Figure 2d). The rock was
clastic with fine to medium grains of feldspar, quartz and other clastic materials. The rock
was massive, gritty and friable. It did not react with dilute HCl.
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Microscopically, the rock was clastic, fine to medium grained and contained rounded to
sub-rounded grains which were poorly sorted. It was composed of quartz, minor feldspar,
sericite and other rock fragments which were cemented by iron oxide. The rock was very
rich in quartz some of which exhited undulose extinction. The quartz grains were mostly
round to sub-rounded. Feldspars were significantly altered into sericite. The rock fragments
contained rounded fine grains of quartz.
Table 4.5d. Modal Composition of Rock Sample from Wuve.
Minerals Volume (%) Characteristics
Quartz 88 Rounded to sub-rounded, mostly undulose
Feldspar 8 Significantly altered into sericite
Sericite 4 Secondary products of altered feldspar
Figure 2d. Sandstone with poorly-sorted grains that are slightly elongated in rock sample
from Wuve.
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4.4.2 Thin Sections of Geophagic Materials
Thin sections of the geophagic materials from Tokorme 1 and Tokorme 2 were done.
4.4.2.1 Thin Section of Geophagic Materials from Tokorme 1
The material was purple-grey, slightly weathered and fine to medium grained (Figure 3a).
This material had a clastic texture and was composed of feldspar, clay and quartz. It
exhibited thin parallel laminations with possible tangential cross-laminations and visible
joints. The material was friable, lacked fissility and did not react with dilute HCl.
Petrographically, the material was fine to medium grained, thinly laminated and exhibited
tangential cross-laminations. It was composed dominantly of clay with minor feldspars and
quartz (Table 4.6a). The quartz grains occured as impregnated clasts of silty sand size
particles embedded in the fine grained clay ground mass. The clay was fine and composed
of mainly fine flakes of sericite. The feldspars were significantly altered to sericite with
well preserved pseudomorphs.
Table 4.6a. Modal Composition of the Geophagic Materials from Tokorme 1.
Minerals Volume (%) Characteristics
Clay 88 Fine grained, mainly flakes of sericites
Feldspar 8 Significantly altered to sericite but with preserved pseudomorphs
Quartz 4 Secondary, occured as impregnated grains
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Figure 3a. Thin lamination of the geophagic materials from Tokorme 1.
4.4.2.2 Thin Section of Geophagic Materials from Tokorme 2
The material was purple-grey, slightly weathered and fine to medium grained (Figure 3b).
This material had a clastic texture and was composed of feldspar, clay and quartz (Table
4.7b). It exhibited thin parallel laminations with possible tangential cross-laminations and
visible joints. The material was friable, lacked fissility and did not react with dilute HCl.
The material was fine to medium grained in thin section, thinly laminated and exhibited
tangential cross-laminations. It was composed dominantly of clay with minor feldspars and
quartz. The quartz grains occured as impregnated clasts of silty sand size embedded in the
fine grained clay ground mass. The material was fine and composed of mainly fine flakes
of sericite. The feldspars were significantly altered to sericite with well preserved
pseudomorphs.
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Table 4.6b. Modal Composition of the Geophagic Materials from Tokorme 2.
Minerals Volume (%) Characteristics
Clay 89 Fine grained, mainly flakes of sericites
Feldspar 7 Mostly altered to sericite but with preserved pseudomorphs
Quartz 4 Secondary, occured as impregnated grains
Figure 3b. Silty-sand size quartz grains occuring as impregnation within the fine grained
matrix of sericite in geophagic materials from Tokorme 2.
4.4.3 X-Ray Diffractograms of Rock Samples
The dominant minerals identified in the diffractograms of the rock samples from the study
areas were quartz (3.34 Å), kaolinite (7.20 Å, 4.26 Å, 2.45 Å), mica (10.02 Å, 1.65 Å), and
feldspar (4.98 Å, 2.56 Å, 1.50 Å) in all the samples. Representative X-ray diffractograms
showing the peaks of dominant minerals are presented in (Figures 4a, 4b, 4c, 4d).
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Figure 4a. X-ray diffractogram of a rock from Tokorme 1.
Figure 4b. X-ray diffractogram of a rock from Tokorme 2.
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Figure 4c. X-ray diffractogram of a rock from Tokorme 3.
Figure 4d X-ray diffractogram of a rock from Wuve.
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4.4.4 X-Ray Diffractogram of the Geophagic Materials
X-ray diffractograms of the geophagic materials from the study sites showed the presence
of quartz as the dominant mineral in all the samples. Kaolinite was also in all the samples.
Other minerals present included feldspar and mica. X-ray diffractograms showing the
peaks of the major minerals in a representative geophagic materials are presented in
(Figures 5a, 5b, 5c, 5d). The dominant minerals identified included quartz (3.34 Å),
kaolinite (7.23 Å, 4.26 Å, 3.52 Å, 2.45 Å), mica (10.05 Å), feldspar (3.15 Å), and
muscovite (4.98 Å, 4.50 Å, 2.57 Å).
Figure 5a. X-ray diffractograms of K-25, K-350, and K-550 clay fraction of the geophagic
materials from Tokorme 1.
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Figure 5b. X-ray diffractograms of K-25, K-350, and K-550 clay fraction of the geophagic
materials from Tokorme 2.
Figure 5c. X-ray diffractograms of K-25, K-350, and K-550 clay fraction of the geophagic
materials from Tokorme 3.
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Figure 5d. X-ray diffractograms of K-25, K-350, and K-550 clay fraction of the geophagic
materials from Wuve.
4.4.5 X-Ray Diffractograms of Soil Samples (clay fractions)
The X-ray diffractograms of the soils from the study sites showed the presence of quartz
as the dominant mineral in all the samples. Kaolinite was also present in all the samples.
Other minerals present included feldspar, muscovite and mica. Representative X-ray
diffractograms showing peaks of the major minerals in representative soil samples are
presented in (Figures 6a, 6b, 6c, 6d). The dominant minerals identified included quartz
(3.35 Å), kaolinite (7.21 Å, 3.58 Å), mica (10.04 Å, 1.99 Å), montmorillonite (15.43 Å),
and muscovite (5.01 Å, 4.7 Å, 2.57 Å).
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Figure 6a. X-ray diffractograms of K-25, K-350, and K-550 clay fraction of soil from
Tokorme 1.
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Figure 6b. X-ray diffractograms of K-25, K-350, and K-550 clay fraction of soil from
Tokorme 2.
Figure 6c. X-ray diffractograms of K-25, K-350, and K-550 clay fraction of soil from
Tokorme 3.
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Figure 6d. X-ray diffractograms of K-25, K-350, and K-550 clay fraction of soil from
Wuve.
4.5 Heavy Metal Content of the Geophagic Materials
The concentrations of ten heavy metals in the four geophagic materials were determined
(Table 4.7). The concentration of vanadium (V) ranged from 169.2 mg kg-1 in Tokorme 2
to 201.5 mg kg-1 in Wuve. The concentration of chromium ranged from 98.7 mg kg-1 in
Tokorme 2 to 117.0 mg kg-1 in Tokorme 3. Cobalt concentration ranged from 19.2 mg kg-
1 in Tokorme 1 to 27.3 mg kg-1 in Tokorme 3. Nickel concentration ranged from 7.0 to 8.6
mg kg-1. The concentration of Cu ranged from 19.6 to 22.4 mg kg-1. The concentration of
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Zn ranged from 22.4 mg kg-1 to 31. 7 mg kg-1. The concentrations of As, Cd, and Hg were
0.9 to 1.2 mg kg-1, 0.5 to 1.1 mg kg-1 and 0.1 to 0.5 mg kg-1 respectively. Lead was detected
only in Tokorme 2 and the concentration was 0.06 mg kg-1.
Table 4.7. Concentration of Heavy Metals in the Geophagic Materials.
Sample V Cr Co Ni Cu Zn As Cd Hg Pb
(mg kg-1)
1 171.9 110.2 19.2 8.6 20.9 29.1 1.2 1.1 0.2 nd
2 169.2 98.7 20.3 8.6 21.9 22.4 1.1 0.6 0.5 0.06
3 175.4 117.7 27.3 7.0 19.6 31.7 0.9 0.7 0.3 nd
4 201.5 100.5 21.0 8.5 22.4 30.0 1.2 0.5 0.1 nd
nd = not detected.
4.5.1 Health Risk Index (HRI) Analyses of Heavy Metals in the Geophagic
Materials
The average daily intake of geophagic materials among women of reproductive age in
Ghana is 70 g day-1 (Tayie et al., 2013). Using the WHO/FAO (2010) average body weight
of 60 kg for the Ghanaian geophagist and a daily intake of 70 g of geophagic materials, the
daily intake of metal (DIM) and the health the risk index (HRI) were calculated (Tables
4.8a, 4.8b, 4.8c, 4.8d). The DIM multiplied by the concentration of the metal in the
geophagic clays (mg kg-1) was estimated according to the formula of Cui et al. (2004). The
health risk level of these heavy metals in the geophagic materials from Anfoega was
computed according to the HRI (USEPA, 2002). It is expressed as the ratio of exposure to
the heavy metal to the oral reference dose (RfD) of metal.
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Table 4.8a. Health Risk Index of Heavy Metals in the Geophagic Materials from Tokorme 1.
Element V Cr Co Ni Cu Zn As Cd Hg Pb
MC 171.9 110.2 19.2 8.6 20.9 29.1 1.2 1.1 0.2 nd
DIM 0.2006 0.1286 0.0224 0.0100 0.0244 0.0340 0.0014 0.0013 0.0002 0.0000
HRI 0.1114 0.7347 0.0250 0.2508 0.0122 0.0023 0.0014 0.1283 0.1167 0.0000
MC = Metal concentration (mg kg-1), DIM = Daily intake of metal = [(MC x DIC)/BW], DIC = Daily intake of
clay
(mg/day), BW = Average body weight (g), HRI = Health risk index, RfD = Reference dose (mg kg-1),
nd = not detected.
Table 4.8b. Health Risk Index of Heavy Metals in the Geophagic Materials from Tokorme 2.
Element V Cr Co Ni Cu Zn As Cd Hg Pb
MC 169.2 98.7 20.3 8.6 21.9 22.4 1.1 0.6 0.5 0.06
DIM 0.1974 0.1151 0.0237 0.0100 0.0256 0.0261 0.0013 0.0007 0.0006 0.0001
HRI 0.1097 0.6580 0.0263 0.2508 0.0128 0.0017 0.0713 0.0700 0.2917 0.0000
MC = Metal concentration (mg kg-1), DIM = Daily intake of metal = [(MC x DIC)/BW], DIC = Daily intake of
clay
(mg/day), BW = Average body weight (g), HRI = Health risk index, RfD = Reference dose (mg kg-1),
nd = not detected.
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Table 4.8c. Health Risk Index of Heavy Metals in the Geophagic Materials from Tokorme 3.
Element V Cr Co Ni Cu Zn As Cd Hg Pb
MC 175.4 117.7 27.3 7.0 19.6 31.7 0.9 0.7 0.3 nd
DIM 0.2046 0.1356 0.0319 0.0082 0.0229 0.0300 0.0011 0.0008 0.0003 0.0000
HRI 0.1137 0.7800 0.0354 0.2043 0.0114 0.0025 0.0583 0.0817 0.1750 0.0000
MC = Metal concentration (mg kg-1), DIM = Daily intake of metal = [(MC x DIC)/BW], DIC = Daily intake of
clay
(mg/day), BW = Average body weight (g), HRI = Health risk index, RfD = Reference dose (mg kg-1),
nd = not detected.
Table 4.8d. Health Risk Index of Heavy Metals in the Geophagic Materials from Wuve.
Element V Cr Co Ni Cu Zn As Cd Hg Pb
MC 201.5 100.5 21.0 8.5 22.4 30.0 1.2 0.5 0.1 nd
DIM 0.2351 0.1173 0.0245 0.0099 0.0261 0.0350 0.0014 0.0006 0.0002 0.0000
HRI 0.1306 0.6700 0.0272 0.2479 0.0131 0.0023 0.0778 0.0583 0.0583 0.0000
MC = Metal concentration (mg kg-1), DIM = Daily intake of metal = [(MC x DIC)/BW], DIC = Daily intake of
clay
(mg/day), BW = Average body weight (g), HRI = Health risk index, RfD = Reference dose (mg kg-1),
nd = not detected.
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4.6 Microbiological Analysis
Bacteria count and population of coliform in the geophagic materials are presented in Table
4.9. The total count ranged from 1.0 x 104 to 1.3 x 106 cfu g-1. The processed-fresh and the
processed-dry geophagic materials contained higher counts than the powdered samples.
The processed-fresh geophagic materials showed a count of 6.0 x 104 to 6.3 x 105 cfu g-1.
Whereas the powdered geophagic materials had the smallest bacterial count of 1.0 x 104
to 2.7 x 105 cfu g-1, the processed dry samples had a total count of 1.0 x 104 to 1.3 x 106
cfu g-1
The processed-smoked sample had a similar total heterotroph count (1.0 x 104 cfu g-1) as
the powdered samples from Tokorme 1 and Tokorme 3. The geophagic materials did not
show any total coliform nor faecal coliform.
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Table 4.9. Total Heterotroph Count, Total Coliform Coliform and Faecal Coliform in the
Geophagic Materials.
Sample Total Count Total Coliform Feacal Coliform
(cfu g-1) (cfu g-1) (cfu g-1)
PF1 6.0x104 nd nd
PF2 3.0x105 nd nd
PF3 6.3x105 nd nd
PF4 4.1x105 nd nd
P1 1.0x104 nd nd
P2 5.0x104 nd nd
P3 1.0x104 nd nd
P4 2.7x105 nd nd
PD1 1.0x104 nd nd
PD2 1.3x106 nd nd
PD3 1.2x105 nd nd
PD4 1.2x105 nd nd
PS 1.0x104 nd nd
1 = Tokorme 1, 2 = Tokorme 2, 3 = Tokorme 3, 4 = Wuve. PF = Processed-fresh,
P = Powder, PD = Processed-dry, PS = Processed-smoked, nd = not detected.
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4.7 Responses from the Interviews
4.7.1 Miners
Four miners were interviewed about their mining activities. All the miners interviewed
were males aged 27 to 50 years. They indicated that clay mining was the only job in town.
Two of the miners entered the business voluntarily while two others were introduced to it
by close relatives. They had been in the business for periods ranging 5 to 30 years. All of
them decribed the work to be very tedious and risky. They indicated that although the
business was lucrative, they were always afflicted by ailment such as joint pains, bodily
pains and fever. Three of the miners conceded that the mining activities posed
environmental and health threats. None of the miners had plans of reclaiming the land after
mining. They were rather of the opinion that nature will reclaim the mined pits. All the
miners indicated that they also practised geophagy and agreed that the habit predisposed
them to ailments such as constipation, diarrhoea and stomach upset.
4.7.2 Dealers (women involved in the processing and marketing)
Ten dealers were interviewed about their activities. All the dealers interviewed were
females aged 22 to 75 years. They had been in the clay business for periods ranging from
5 to 30 years. They all indicated that they obtained the raw materials from local miners and
that they processed them by themselves. While nine (9) indicated that they practised
geophagy, one was not willing to indicate whether she ingested the material or not. Reasons
they assigned for practising geophagy included, test to determine quality during processing,
nausea, sometimes craving during pregnancy, to alleviate chest pain, ease of heart burn,
control of diarrhoea and mere craving for the material. Eight (8) of them recounted benefits
they derived from eating the clay which included control for nausea, diarrhoea and stomach
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aches. Two others claimed they were not sure of the benefits of ingesting the material. They
also indicated that consumption of the clay caused constipation, white stool and bloated
stomach. Other women interviewed, outside the dealers, confirmed the views of the dealers
about the practice of geophagy.
4.7.3 Health Personnel
Health personnel were interviewed at the Wuve Health Post, the Anfoega Hospital and the
Margaret Marquart Hospital at Kpando. They all admitted that earth eating was prevalent
in their area. They were of the opinion that the practice could have health implications.
However, none of the outfits had records on practitioners who might have reported at their
facilities with ailments due to the practice of geophagy. They all conceded that as part of
their public health responsibilities they should have captured possible health implications
of mining activities, processing and ingestion of the materials over the many years that the
business had gone on in the area.
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CHAPTER FIVE
DISCUSSION
5.1 Physical Properties
5.1.1 Particle Size Distribution and Texture
The petrographic examinations revealed that the rock samples were mainly sandstones
(quarzitic). The diffractograms also showed high amounts of quartz in the soils, rocks and
geophagic materials. These results explain the high amounts of sand in the soils. However,
the soils from Tokorme 3 showed relatively high amounts of clay which may be due to the
fact that the Buem units also contained appreciable amounts of calcareous and argillaceous
materials (Kesse, 1985). Moreover, the relatively lower altitude of Tokorme 3 might have
resulted in it receiving a lot of eroded materials from higher elevation. Dickson et al.
(1995), had reported that soils from the area were formed from the eroded materials of the
Togo units and are made up of sedimentary rocks which are basically shales and
sandstones. The geophagic materials contained high amount of clay. They contained
moderate amounts of silt and a very small amounts of sand. The petrographic analysis of
the geophagic material showed that 88% of its volume was made up of clastic sedmentary
clay (mudstone). The high clay content of the geophagic materials makes them easily
ingestible (Ekosse et al., 2010; Ngole et al., 2010) and less harmful to practitioners (Konta,
1995).
5.1.2 Bulk Density
Generally, all the soils showed consistent increase in bulk density with depth. Bulk density
typically increases with soil depth due to decreasing levels of organic matter content, less
aggregation, and root proliferation and compaction caused by the weight of the overlying
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layers (Tsimba et al., 1999). Soils and horizons with high organic matter tend to have lower
bulk density probably due to higher biological activity which results in the creation of more
soil pores (Alexander, 1980). The bulk density of the soils were lower than levels restrictive
to root growth (Hunt and Gilkes, 1992; McKenzie et al., 2004).
5.2 Chemical Properties
5.2.1 pH (H2O) and pH (CaCl2) of Soils and Geophagic Materials
In general, the soils from Tokorme 2, Tokorme 3, and Wuve were acidic. On the other
hand, the soils from Tokorme 1 was slightly alkaline. The acidic pH of the soils may be
attributed mainly to the mineralogy of the parent materials. The soils were derived from
SIALIC rocks (rocks rich in silica and alumina), mainly sandstones. Also the x-ray
diffractograms of the soils showed that they contained high amounts of SIALIC minerals
namely quartz, feldspars and muscovite. The relatively higher pH (H2O) of Tokorme 1
could be partly due to its location at a higher altitude and thus experienced less leaching of
the basic cations. The pH values of the geophagic materials were generally strongly acidic.
The low pH of the geophagic materials could be attributed to the high concentration of
SIALIC minerals particularly quartz, feldspars and muscovite. Abrahams and Parsons
(1997) reported that many geophagic materials are acidic thus imparting a sour taste to
them. The sour taste of the geophagic materials is beneficial during pregnancy to prevent
excessive secretion of saliva and thus reduces nausea as reported by (Ibeanu et al., 1997)
among women in Kenya and Nigeria.
The pH (CaCl2) values of the soil samples and their associated geophagic materials were
lower than their pH (H2O) values. Thus, their ΔpH [pH (H2O) - pH (CaCl2)] would be
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negative. The negative ΔpH values is an indication that the geophagic materials would
possess negative charges (Tan, 1982).
5.2.2 Electrical Conductivity
The soils and their associated geophagic materials from the study sites were non-saline
because their EC values were far lower than the critical value of 2 dS m-1 (FAO, 1988).
The low EC levels of the geophagic materials implies that they contained low levels of
dissolved salts. Thus the geophagic materials from Anfoega may show poor flocculation
when ingested. This is a positive sign because the geophagic materials will not promote
the coating of the intestinal mucosa.
5.2.3 Total Nitrogen Content
The total nitrogen content of the soils and their associated geophagic materials was very
small and decreased with decreasing organic carbon content. Organic matter (carbon) is a
good source of N from which microbes could synthesize protein (Baddock and Nelson,
2000; Pierzynski et al, 2000).
5.2.4 Organic Carbon
The organic carbon content of the soils declined sharply with depth. This result was due to
the fact that the soil surface served as the repository for litter fall from vegetation and was
also the zone of vigorous microbial activities (Nelson et al. 1994). Generally low levels of
organic carbon in the soils may be mainly due to the generally low biomass generation
from the savanna woodland vegetation in the area. The geophagic materials contained very
low amounts of organic carbon most probably due to their location, more than 9 m below
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the soil surface. With low levels of organic carbon, the geophagic materials would also be
associated with low levels of microbes in the pits.
5.2.5 Available Phosphorus and Total Phosphorus content of the Soils and
Geophagic Materials
The available P content of all the soils was low and decreased with soil depth and pH. The
geophagic materials also contained very low available P. The acidic nature of the soils and
the respective geophagic materials might have contributed to fixing of P and thus reducing
the levels of available P (Nartey, 1994). The soils and the geophagic materials also
contained small amounts of total P. The geophagic materials contained relatively higher
levels of total P probably due to the fact that they fixed more P because of their lower pH
levels.
5.2.6 Exchangeable Bases and Cation Exchange Capacity
All the soils and the geophagic materials showed very low levels of exchangeable bases
probably due to the paucity of these bases in the parent materials and also leaching. The
soils had moderate amounts of CEC. The geophagic materials had higher CEC levels than
the soil. The levels of exchangeable bases and CEC in the soils and the geophagic materials
may be due to a combination of factors including types of clay minerals, amount of clay
and organic carbon content (Landon, 1991). The relatively higher CEC of the geophagic
mterials may be due to the higher amounts of clay they contained.
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5.3 Mineralogy
5.3.1 Thin Section Petrography of the Geophagic Materials and Rocks
The composition of the geophagic materials were dominated by clay minerals. They also
contained quartz and sericite (degraded feldspar). This result is due to the fact that the
materials were clastic sedimentary rocks which were lithologically silty mudstones. The
thin section of the rock also revealed quartz and relatively small amounts of feldspar and
sericite. The presence of these minerals showed that the rocks were sedimentary sandstones
(quartz arenite). Kesse (1985) had reported that the Buem formation from which these
rocks were obtained consist of calcareous, argillaceous, greywacke and ferruginous shale,
sandstones and conglomerates. The thin section results revealed that the geophagic
materials and the rocks were dominated by SIALIC minerals.
5.3.2 X-Ray Examination
5.3.2.1 The X-ray Diffractograms of Rocks
The X-ray diffractograms of representative rock samples revealed quartz, feldspar,
muscovite and kaolinite as the dominant minerals present in all the samples. Thus, the
samples were clearly SIALIC in mineralogical composition. The Bliku hills of Anfoega
where the rock samples were taken from, belong to the Buem formation which according
to Kesse, (1985) are predominantly composed of shales and sandstones.
5.3.2.2 The X-ray Diffractograms of the Soils
The X-ray diffractograms of the soils were dominated by minerals like quartz (3.35 Å),
kaolinite (7.21 Å, 3.58 Å), mica (10.04 Å, 1.99 Å), montmorillonite (15.43 Å) and
muscovite (5.01 Å, 4.7 Å, 2.57 Å) in all the samples. These minerals were also revealed by
the x-ray diffractograms of the rocks. These results showed that the soils were probably
Fe
Fe
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formed in situ from the underlying rocks. The high quartz content of the soils probably
explains why the soils contained high amount of sand. The collapsed peaks at 12.28 (2Ө)
of the samples at 550 oC is a comfirmation of the presence of kaolinite.
5.3.2.3 The X-ray Diffractograms of the Geophagic Materials
The X-ray diffractograms of the geophagic materials showed dominant minerals like quartz
(3.34 Ǻ), kaolinite (7.23 Å, 4.26 Å, 3.52 Å, 2.45 Å), mica (10.05 Å), feldspar (3.15 Å) and
muscovite (4.98 Å, 4.50 Å, 2.57 Å). All these minerals were also revealed in the soils as
well as the rock samples. The collapse of peaks at 12.28 (2Ө) of the geophagic materials
at 550 oC confirms the presence of kaolinite. The low pH values and the presence of
minerals such as quartz, muscovites and feldspars suggest that the geophagic materials
might have been derived from the overlying rocks
5.4 Levels of Heavy Metals (HM) in Geophagic Materials
The HM content of the geophagic materials were low probably due to their inherently low
levels in their parent material and also the low effect of human activity. The health risk
index levels of the heavy metals contained in 70 g (average daily intake) of the geoghagic
clay were all less than 1.0 indicating that the geophagic materials from Anfoega appear to
be safe for human consumption. If the hazard index exceeds 1.0, there could be a potential
human health effect (Huang et al., 2008). The health risk assessment for all the sites in this
study indicated that the geophagic materials from Anfoega do not pose any HM-related
health hazard. However, geophagists would have to be wary of the cumulative effects of
long term exposure to the metals. Long term exposure to Pb, As, Cd, Cr and Hg have been
reported to cause gastro-enteritis, inhibition of haemoglobin formation, sterility,
miscarriage, growth retardation, central nervous system disorder, kidney dysfunction,
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hypertension and mental retardation (Amdur, 1991; Ming-HO, 2001; Meharg, 2005).
Although some metals such as Cu, Co, Ni, V and Zn are essential micronutrients, they can
also become harmful to the geophagists after prolonged eating of clay materials.
5.5 Microbial Analysis
5.5.1 Heterotrophic Bacterial Count and Coliform Numbers in the Geophagic
Meterials
The total heterotroph count in the geophagic materials generally followed the order,
processed-fresh ≥ processed-dry > powdered > smoked. The relatively high number of
bacteria load present in the freshly processed material was probably the result of
unhygienic or insanitary conditions under which the material was processed. However, no
total coliform or faecal coliform was detected in the samples. The coliform group of
bacteria are reliable indicators of faecal pollution and general insanitary conditions. Thus,
their absence in all the samples is indicative of the possible absence of toxigenic
microorganisms in the samples. Looking at the depth from which the materials were mined
and their strong acidic nature coupled with the fact that there was no coliform group of
bacteria present in all the samples, the high bacteria load would most probably have been
introduced during the production stage through poor handling and exposure to
environmental organisms.
Clearly, application of heat to the material (processed smoked) might have reduced the
bacteria load. In general, the results of the microbiological analysis suggest that the
microbial contamination of the material, occured during processing. The material, therefore
appears to be naturally safe for consumption. Although generally perceived as harmful,
geophagia may enhance bio-activity and maintenance of normal intestinal flora (Tano-
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Debrah and Bruce-Baiden, 2010), the production of natural antibiotics (Abrahams, 2002)
and biodegradable toxic substances in the gastrointestinal tract (Ragnarsdottir, 2000).
5.6 Questionnaire
Information gathered from the interviews revealed that the mining activities posed serious
threat to the environment and the people in the study area. There appeared to be no
reclamation going on because the activities of the miners were not regulated by the
Environmental Protection Agency. Although not medically ascertained, the ingestion of
the material seemed to provide some benefits to the consumers. The interviews also
revealed that the health facilities in the study area had no records regarding the health
implications of ingesting the material.
Lack of medical records on geophagy may be probably due to the fact that the medical
personnel within the study area did not probe deep to determine the aetiology of some
diseases their patients present. It appeared that all cases were generally treated. On the
other hand, the reluctance of the people to seek medical attention when they fall ill, their
inability to give proper accounts of the cause of their illnesses and failure to disclose their
geophagic status might have contributed to the lack of the medical records on the practice.
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CHAPTER SIX
CONCLUSIONS AND RECOMMENDATIONS
6.1 Conclusions
The texture of the soils was dominated by sand except for Tokorme 2 which had
high clay content, in the surface and subsurface layers. The geophagic materials
contained higher amounts of clay.
The pH of the soils from Tokorme 1, Tokorme 3 and Wuve ranged from slightly
acidic to moderately acidic. The pH of the soil from Tokorme 2 was moderately
acidic in the surface soil but strongly acidic in the subsoil and bottom layers. The
pH of the geophagic materials was strongly acidic.
With higher amounts of clay, the geophagic materials had higher CEC (18.0 to 23.2
cmolc kg-1) than the soils (5.3 to 22.6 cmolc kg-1).
The thin section petrography showed quartz, feldspar and sericite as the dominant
minerals in all the rock samples. The geophagic materials also showed the presence
of similar minerals but in smaller amounts. The thin sections of the geophagic
materials also revealed high amounts of clay minerals.
The x-ray diffractograms showed that the rock, soil samples and the geophagic
materials contained high amounts of quartz, kaolinite, muscovite and feldspars.
They also contained some small amounts of chlorite, haematite and
montmorillonite.
The high amount of SIALIC minerals in the soils shows that they were derived in-
situ from the underlying sandstones.
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The strongly acidic pH of the geophagic materials was probably due to the
accumulation of SIALIC minerals through leaching of the overlying sandstone.
The health risks estimates of the geophagic materials, calculated based on a
consumption rate of 70 g day-1, indicated that the concentrations of all the heavy
metals were below the critical levels that would be injurious to human health.
However, long term ingestion of these materials could lead to bioaccumulation.
Microbial analysis revealed that the geophagic materials were naturally safe for
consumption but processing under unhygienic conditions could introduce
microorganisms.
The results of the study revealed that the health facilities in the study area namely,
the Wuve Health Post, the Anfoega Hospital and the Margaret Marquat Hospital,
Kpando had no records on the health implications of geophagia being practised by
mainly women in the study area.
6.2 Recommendations
This work did not conclusively show the direct linkage between the geophagic
materials and the overlying rocks and soils. To ascertain that the geophagic
materials were formed through leaching of the overlying sandstone, more work
including radioactive studies, need to be carried out.
Eventhough, the health risk index analysis of heavy metals in the geophagic
materials from Anfoega indicates that the materials are not unsafe for consumption,
there is the danger of bioaccumulation as a result of long term exposure. There is
therefore the need for proper and intensive education by the public health units of
the health facilities in the study area on the potential dangers of prolong practice of
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geophagy. Also, periodic health checks must be done by the health personnel to see
if there is any possible build up of heavy metals in the geophagic individuals who
visit their facilities.
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APPENDICES
Appendix A
Questionnaire for Consumers
1. Sex…………………………………………………………………………………..
2. Age………………………………………………………………………………….
3. Do you ingest the white clay? Yes / No.
4. Where do you obtain the material from?.....................................................................
5. Do you have any idea as to how the material is prepared? Yes / No.
6. For how long have you been ingesting the material?..................................................
7. How did you start the practice?...................................................................................
8. Why do you ingest the material?.................................................................................
9. What are the benefits of ingesting the material?.........................................................
10. Have you experienced some side effects from ingesting the white clay? Yes / No
11. If yes, state them……………………………………………………………………
12. If yes, what do you think are the causes of the side effects? .......................................
13 In your opinion, how do you think the side effects can be minimized or eliminated?
....................................................................................................................................
14 Would you wish to stop the habit of eating the white clay? Yes/ No
15 If yes, why?...............................................................................................................
16 If no, why?..................................................................................................................
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Appendix B
Questionnaire for Dealers in White Clay Business
1. Sex………………………………………………………………………………….
2. Age…………………………………………………………………………………
3. How did you get into this business?............................................................................
4. How long have you been in this business?..................................................................
5. Any reason(s) for doing this business?......................................................................
6. Where do you obtain the material from?.....................................................................
7. Do you process it yourself? Yes / No........................................................................
8. If yes, kindly describe the procedures involve in processing?.................................
9. Do you add anything to the clay when processing? Yes / No .................................
10. If yes, kindly list them and state their function(s)…………………………………
11. Why do you process it? ...........................................................................................
12. Do you eat it yourself? Yes / No .................................................................................
13. If yes why? ...............................................................................................................
14. If no, why?.................................................................................................................
15. What benefit do you derive from eating it?................................................................
16. Do you experience any side effects in ingesting it? Yes / No
17. If yes, state the side effects………………………………………………………….
18. List any challenges you face in the business………………………………………..
19. Do you receive complaints from patrons of the white clay? Yes / No
20. If yes, state them…………………………………………………………………….
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Appendix C
Questionnaire for Miners
1. Sex…………………………………………………………………………………..
2. Age………………………………………………………………………………….
3. How long have you been in this business? .................................................................
4. Who introduced or initiated you into this business of mining clays? .........................
5. Why do you engage in this business? ........................................................................
6. Are you the owner of the land? Yes / No……………………………………………
7. If No, how did you acquire the concession?
8. Are you aware of any environmental problems this mining of clay activities cause?
Yes / No
9. If Yes, list them .........................................................................................................
10. Are you aware of any health risk? Yes No…………………………………………
11. Have you experienced any health problems yourself that you can associate with the
mining? Yes / No
12. If yes, kindly state the health problems……………………………………………..
13. How do you sell the mined clay material? .................................................................
14. Who are your customers?...........................................................................................
15. Is the business lucrative? Yes / No………………………………………………….
16. If No, why are you still involved?..............................................................................
17. Do you ingest the material yourself? Yes / No……………………………………..
18. If Yes, why? ..............................................................................................................
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19. Do you experience any side effects from the ingestion? Yes / No
20. If yes, list them……………………………………………………………………...
21. If you do not ingest it yourself, why?.........................................................................
22. Are there any health related problems of the physical activity involved in the
mining? Yes/No
23. If yes, state them…………………………………………………………………….
24. Do you reclaim the land after mining? Yes/No
25. If Yes, how?...............................................................................................................
26. If No, why?................................................................................................................
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Appendix D
Questionnaire for Health Facilities / EPA
1. Is your outfit aware of the white-clay business at Anfoega and its environs? Yes / No
2. Briefly, what do you know about the business?.................................................................
3. Is your outfit aware of any health implications of the business? Yes/No
4. If your answer to Question 3 is yes, list some of the health implications that have come
to the attention of your outfit………………………………………………………………..
5. List the health implications you have stated in Question 4 according to the order of
prevalence…………………………………………………………………………………
6. Are there any environmental implications of the business that have come to the notice
of your outfit? Yes/No………………………………………………………………………
7. If your answer to Question 6 is yes, list up to five most important environmental issues
that have come to the attention of your outfit…………………………………………….
8. If your answer to Qestion 3 is No, what do you think could be some of the potential
health related implications of the white clay business? ..........................................................
9. What advice would you have for those who produce the material and the
consumers?………………………………………………………………………………….
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