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===Health effects resulting from the deficiency and excessiveness of selenium===

===Health effects resulting from the deficiency and excessiveness of selenium===

According to Fordyce,<ref name=Fordyce>Fordyce, F., 2010, Selenium deficiency and toxicity in the environment, ''in'' O. Selinus, B. Alloway, J. A. Centeno, J.A., Finkelman, R.B., Fuge, R., Lindh, U. and Smedley, P., (eds.) 2010. Essentials of Medical Geology. Elsevier, Amsterdam, 375-413.</ref> selenium is found in phosphatic rocks, coals, organic-rich shales and sulphide mineralization. It occurs in the soil in the form of selenites (Se4+), selenates (Se6+), selenides (Se2-) and elemental selenium (Se0).

According to Fordyce,<ref name=Fordyce>Fordyce, F., 2010, Selenium deficiency and toxicity in the environment, ''in'' O. Selinus, B. Alloway, J. A. Centeno, R. B. Finkelman, R. Fuge, U. Lindh, and P. Smedley, eds., 2010, Essentials of medical geology: Amsterdam, Elsevier, p. 375–413.</ref> selenium is found in phosphatic rocks, coals, organic-rich shales and sulphide mineralization. It occurs in the soil in the form of selenites (Se4+), selenates (Se6+), selenides (Se2-) and elemental selenium (Se0).

It can accumulate in the kidneys, liver, marrow, myocardium, pancreas, lungs, skin and hair. <ref name=Fordyce />

It can accumulate in the kidneys, liver, marrow, myocardium, pancreas, lungs, skin and hair. <ref name=Fordyce />

====Health effects of asbestos====

====Health effects of asbestos====

Asbestos is an industrial term that comprises six different natural fibrous silicates. They include: grunerite, (Fe, Mg)7 Si8O22(OH)2, riebeckite, Na2(Fe,Mg)3Fe2Si8O22(OH)2, tremolite, Ca2Mg5Si8O22(OH)2, anthophyllite, (Mg, Fe)7Si8O22(OH)2 and actinolite, Ca2(Fe, Mg)5Si8O22(OH)2 all belonging to the amphibole group while the sixth mineral, chrysotile, Mg6(Si4O10)(OH)8 is a serpentine.<ref name=Ljung>Ljung, K., A. de Vos, A. Cook, and P. Weinstein, 2010, An Overview of Medical Geology Issues in Australia and Oceania. In: Selinus, O., Finkelman, R.B. and Centeno, J., Eds, Medical Geology – A Regional Synthesis. Springer, Germany, 107-135.</ref> These minerals can exist together as a homogenous mineral deposit or in combination with other minerals. Asbestos have found diverse applications owing to its flexibility, high tensile strength and resistance to heat, chemicals, and electricity. Thus, they are used in the manufacture of pipe lagging, asbestos roofing sheets, clutches and brake linings and insulation materials.<ref name=Ljung />

Asbestos is an industrial term that comprises six different natural fibrous silicates. They include: grunerite, (Fe, Mg)7 Si8O22(OH)2, riebeckite, Na2(Fe,Mg)3Fe2Si8O22(OH)2, tremolite, Ca2Mg5Si8O22(OH)2, anthophyllite, (Mg, Fe)7Si8O22(OH)2 and actinolite, Ca2(Fe, Mg)5Si8O22(OH)2 all belonging to the amphibole group while the sixth mineral, chrysotile, Mg6(Si4O10)(OH)8 is a serpentine.<ref name=Ljung>Ljung, K., A. de Vos, A. Cook, and P. Weinstein, 2010, An overview of medical geology issues in Australia and Oceania, ''in'' O. Selinus, R. B. Finkelman, and J. Centeno, eds., Medical geology—A regional synthesis: Berlin, Springer, p. 107–135.</ref> These minerals can exist together as a homogenous mineral deposit or in combination with other minerals. Asbestos have found diverse applications owing to its flexibility, high tensile strength and resistance to heat, chemicals, and electricity. Thus, they are used in the manufacture of pipe lagging, asbestos roofing sheets, clutches and brake linings and insulation materials.<ref name=Ljung />

Notwithstanding their many applications, they are extremely dangerous to human health. Because of their fibrous structure, asbestos can penetrate deep into the lungs when inhaled causing different forms of damage to the affected tissues. This disease is known as asbestosis–a fatal lung disease that saps the patient of strength. Such inhalation can also lead to lung cancer, cancer of the gastrointestinal tract and pleural mesothelioma.<ref name=Setal2010 />

Notwithstanding their many applications, they are extremely dangerous to human health. Because of their fibrous structure, asbestos can penetrate deep into the lungs when inhaled causing different forms of damage to the affected tissues. This disease is known as asbestosis–a fatal lung disease that saps the patient of strength. Such inhalation can also lead to lung cancer, cancer of the gastrointestinal tract and pleural mesothelioma.<ref name=Setal2010 />

====Dangers of Geophagy====

====Dangers of Geophagy====

Despite the various benefits of geophagy, it can be detrimental to human health. The cation exchange capacity and the adsorption potential of clay and shale can lead to the deficiency of certain elements in the body. For instance, in Turkey, iron-deficiency anemia has been linked to the consumption of clays especially sepiolite and montmorillonite of high capillary electrochromatography.<ref name=Abraham>Abraham, P. W., 2013, Geophagy and the Involuntary Ingestion of Soil. In: O. Selinus, Essentials of Medical Geology: Springer Netherlands, pp. 433-454.</ref> This is caused by the effectiveness of clays to adsorb iron. In addition, the consumption of clay has been confirmed to cause potassium deficiency–a condition known as hypokalemia. It is reflected by low concentration of potassium in the blood. In a situation whereby there is concurrent deficiency of iron and potassium, a disease known as cachexia Africana results. This can, however, be treated by iron and potassium supplementation programmes.

Despite the various benefits of geophagy, it can be detrimental to human health. The cation exchange capacity and the adsorption potential of clay and shale can lead to the deficiency of certain elements in the body. For instance, in Turkey, iron-deficiency anemia has been linked to the consumption of clays especially sepiolite and montmorillonite of high capillary electrochromatography.<ref name=Abraham>Abraham, P. W., 2013, Geophagy and the involuntary ingestion of soil, ''in'' O. Selinus, Essentials of medical geology: Amsterdam, Springer, p. 433–454.</ref> This is caused by the effectiveness of clays to adsorb iron. In addition, the consumption of clay has been confirmed to cause potassium deficiency–a condition known as hypokalemia. It is reflected by low concentration of potassium in the blood. In a situation whereby there is concurrent deficiency of iron and potassium, a disease known as cachexia Africana results. This can, however, be treated by iron and potassium supplementation programs.

In Turkey, the consumption of soil by women and children has been noted to cause the combined deficiency of iron and zinc.<ref name=Abraham /> According to a research conducted, deficiency of zinc leads to growth retardation and delayed puberty. Thus, for persons that have low concentration of zinc in the blood, geophagy helps to further lower the level of zinc in the blood. However, zinc supplementation programmes have been supremely effective in improving growth and normal puberty maturation in this region.

In Turkey, the consumption of soil by women and children has been noted to cause the combined deficiency of iron and zinc.<ref name=Abraham /> According to a research conducted, deficiency of zinc leads to growth retardation and delayed puberty. Thus, for persons that have low concentration of zinc in the blood, geophagy helps to further lower the level of zinc in the blood. However, zinc supplementation programs have been supremely effective in improving growth and normal puberty maturation in this region.

In an environment where the soil is contaminated with lead, geophagy could expose little children to lead poisoning. This could lead to damage to the developing brain and nervous system. Lead is particularly dangerous to young children as research has shown that there is no safe level for lead in children.

In an environment where the soil is contaminated with lead, geophagy could expose little children to lead poisoning. This could lead to damage to the developing brain and nervous system. Lead is particularly dangerous to young children as research has shown that there is no safe level for lead in children.

From ancient times, man has explored geologic materials and put them to use for his well- being. Some of them had been used domestically while others have many industrial, as well as medical applications, depending on available technology.

From ancient times, man has explored geologic materials and put them to use for his well- being. Some of them had been used domestically while others have many industrial, as well as medical applications, depending on available technology.

Therapeutic application of medical geology refers to the use of geological materials in the treatment of diseases. Nigeria has a lot of potentials for the therapeutic applications of geologic materials. For instance, the country is blessed with thermal mineralized waters in various parts of the nation such as the Ikogosi Warm Spring in Ekiti State, the mineralized thermal springs at Awe in Nasarawa State and those in the onshore/offshore locations of Delta, Rivers, Cross Rivers, Edo, Bayelsa and Imo States. In addition, Nigeria is blessed with abundance of medicinal clays such as kaolin and [[bentonite]] in most states of the federation. Also, there is abundance of peat, trona and potash in some states (after Nghargbu et al, 2013<ref name=Ngha>Nghargbu, K., Ponikowska, I., Latour, T., Kurowska, E., Schoeneich, K., and Alagbe, S.A., 2013a. Balneo-therapeutic Quality of Water from Thermal Chlorosodic Springs of the Middle Benue Trough, Nigeria. Unpublished Work, Nasarawa State University, Keffi, Nigeria,1-9.</ref><ref name=Nghb>Nghargbu, K., Ponikowska, I., Latour, T., Kurowska, E., Schoeneich, K., and Alagbe, S.A. 2013b. Geomedical Resources Inventory: The Nigerian Content. Unpublished Work, Nasarawa State University, Keffi, Nigeria, 1-15.</ref>).

Therapeutic application of medical geology refers to the use of geological materials in the treatment of diseases. Nigeria has a lot of potentials for the therapeutic applications of geologic materials. For instance, the country is blessed with thermal mineralized waters in various parts of the nation such as the Ikogosi Warm Spring in Ekiti State, the mineralized thermal springs at Awe in Nasarawa State and those in the onshore/offshore locations of Delta, Rivers, Cross Rivers, Edo, Bayelsa and Imo States. In addition, Nigeria is blessed with abundance of medicinal clays such as kaolin and [[bentonite]] in most states of the federation. Also, there is abundance of peat, trona and potash in some states (after Nghargbu et al, 2013<ref name=Ngha>Nghargbu, K., I. Ponikowska, T. Latour, E. Kurowska, K. Schoeneich, and S. A., Alagbe, 2013a, Balneo-therapeutic quality of water from thermal chlorosodic springs of the Middle Benue Trough, Nigeria: Unpublished paper, Nasarawa State University, Keffi, Nigeria, 9 p.</ref><ref name=Nghb>Nghargbu, K., I. Ponikowska, T. Latour, E. Kurowska, K. Schoeneich, and S. A. Alagbe, 2013b, Geomedical Resources Inventory: The Nigerian Content: Unpublished work, Nasarawa State University, Keffi, Nigeria, 15 p.</ref>).

Sadly, lack of technological know-how and fewer number of medical geology practitioners in Nigeria have limited the extraction of these resources for medical purposes.

Sadly, lack of technological know-how and fewer number of medical geology practitioners in Nigeria have limited the extraction of these resources for medical purposes.

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UNN_Medical_Geology_Fig_12.png|{{figure number|12}}Tangarahu Spring, Awe, Nigeria.<ref name=Ngha /><ref name=Nghb />

UNN_Medical_Geology_Fig_12.png|{{figure number|12}}Tangarahu Spring, Awe, Nigeria.<ref name=Ngha /><ref name=Nghb />

UNN_Medical_Geology_Fig_13.png|{{figure number|13}}Geology of Awe and environs. QUATERNARY (A) Alluvium (B) Tertiary To Recent Volcanics; CRETACEOUS (C) Nkporo Shale Group (D) Awgu-Ndeabo Shale Group (E) Ezeaku Shale Group (F) Asu River Group; PRECAMBRIAN (G) Basement Complex (H) Anticlinal Axis (I) Synclinal Axis (J) Fracture.<ref name=Ngha /><ref name=Nghb />]]

UNN_Medical_Geology_Fig_13.png|{{figure number|13}}Geology of Awe and environs. Quaternary (A) Alluvium (B) Tertiary To Recent Volcanics; Cretaceous (C) Nkporo Shale Group (D) Awgu-Ndeabo Shale Group (E) Ezeaku Shale Group (F) Asu River Group; Precambrian (G) Basement Complex (H) Anticlinal Axis (I) Synclinal Axis (J) Fracture.<ref name=Ngha /><ref name=Nghb />

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[[Bentonite]] is an absorbent aluminum phylosilicate rock containing mostly montmorillonite. It is formed mainly from volcanic ash. The name comes from the largest known deposit of bentonite clay located in Fort Benton, Wyoming, USA. It is a unique clay due to its ability to produce electronegative charge when hydrated giving it the ability to attract and neutralize toxins which are electropositive. When mixed with water, bentonite rapidly swells open like a highly porous sponge, making the toxins and heavy metal to be drawn in through electrical attraction without leaching away any of its beneficial elements. This phenomenon prevents toxic molecules from passing through the walls of the intestines and entering the bloodstream; instead, they are eliminated from the body through the kidneys.

[[Bentonite]] is an absorbent aluminum phylosilicate rock containing mostly montmorillonite. It is formed mainly from volcanic ash. The name comes from the largest known deposit of bentonite clay located in Fort Benton, Wyoming, USA. It is a unique clay due to its ability to produce electronegative charge when hydrated giving it the ability to attract and neutralize toxins which are electropositive. When mixed with water, bentonite rapidly swells open like a highly porous sponge, making the toxins and heavy metal to be drawn in through electrical attraction without leaching away any of its beneficial elements. This phenomenon prevents toxic molecules from passing through the walls of the intestines and entering the bloodstream; instead, they are eliminated from the body through the kidneys.

Based on the above properties, bentonite is an important healing clay. It can be applied on the skin to remove eczema and also applied on the face ([[:File:UNN_Medical_Geology_Fig_15.png|Figure 15]]) and other parts of the body as a cream where it leaves the skin smooth and radiant.<ref>Knishinsky, R., 1998, The Clay Cure. Healing Arts Press, Rochester, 112p.</ref>

Based on the above properties, bentonite is an important healing clay. It can be applied on the skin to remove eczema and also applied on the face ([[:File:UNN_Medical_Geology_Fig_15.png|Figure 15]]) and other parts of the body as a cream where it leaves the skin smooth and radiant.<ref>Knishinsky, R., 1998, The clay cure: Rochester, New York, Healing Arts Press, 112 p.</ref>

===Kaolin===

===Kaolin===

===Milk of Magnesia===

===Milk of Magnesia===

[[File:UNN_Medical_Geology_Fig_16.png|thumb|400px|{{figure number|16}}Milk of Magnesia (sourced from: www.bing.com/images on 31/03/2014)]]

[[File:UNN_Medical_Geology_Fig_16.png|thumb|400px|{{figure number|16}}Milk of Magnesia]]

Milk of magnesia is a name given to magnesium hydroxide – an inorganic compound with the formula, “Mg(OH)2”. It forms a milk-like appearance when in suspension, hence the name. The solid mineral form of magnesium hydroxide is brucite [Mg(OH)2] which occurs in clay minerals especially in chlorite. Brucite occupies the interlayer position which is normally occupied by monovalent and divalent cations such as Na+, K+, Mg+ and Ca+ in chlorite. In this manner, chlorite interlayer is cemented by brucite and can neither swell nor shrink.<ref>Zumdahl, S. S., 2009. Chemical Principles. Houghton Miffin Company, 120p.</ref>

Milk of magnesia is a name given to magnesium hydroxide – an inorganic compound with the formula, “Mg(OH)2”. It forms a milk-like appearance when in suspension, hence the name. The solid mineral form of magnesium hydroxide is brucite [Mg(OH)2] which occurs in clay minerals especially in chlorite. Brucite occupies the interlayer position which is normally occupied by monovalent and divalent cations such as Na+, K+, Mg+ and Ca+ in chlorite. In this manner, chlorite interlayer is cemented by brucite and can neither swell nor shrink.<ref>Zumdahl, S. S., 2009, Chemical principles: New York, Houghton Mifflin, 120 p.</ref>

Milk of magnesia is used as an antacid to neutralize stomach acid. Hydroxide ions from the Mg(OH)2 combine with acidic hydroxide (H+) ions produced from hydrochloric acid by parietal cells in the stomach to produce water. It is made into capsules and chewable tablets for use against constipation and indigestion ([[:File:UNN_Medical_Geology_Fig_16.png|Figure 16]]).

Milk of magnesia is used as an antacid to neutralize stomach acid. Hydroxide ions from the Mg(OH)2 combine with acidic hydroxide (H+) ions produced from hydrochloric acid by parietal cells in the stomach to produce water. It is made into capsules and chewable tablets for use against constipation and indigestion ([[:File:UNN_Medical_Geology_Fig_16.png|Figure 16]]).

As a laxative, milk of magnesia absorbs fluid from the body, through osmotic pressure, into the lumen of the small intestine while retaining the fluid already in the small intestine.<ref>Pradyot, P., 2002. Handbook of Inorganic Chemicals. McGraw-Hill, New York, 186p.</ref> First, Mg2+ is poorly absorbed from the intestinal tract, so it draws water from the surrounding tissue by osmosis. Not only does this increase the water content, it softens the faeces and increases the volume of faeces in the intestine which naturally stimulates intestinal motility. Furthermore, Mg2+ ions cause the release of cholecystokinin (CCK) which results in intraluminal accumulation of water, electrolytes and increased intestinal motility. This stimulates the nerves of the colon to distend leading to peristalsis culminating in the evacuation of its contents.

As a laxative, milk of magnesia absorbs fluid from the body, through osmotic pressure, into the lumen of the small intestine while retaining the fluid already in the small intestine.<ref>Pradyot, P., 2002, Handbook of inorganic chemicals: New York, McGraw-Hill, 186 p.</ref> First, Mg2+ is poorly absorbed from the intestinal tract, so it draws water from the surrounding tissue by osmosis. Not only does this increase the water content, it softens the feces and increases the volume of feces in the intestine which naturally stimulates intestinal motility. Furthermore, Mg2+ ions cause the release of cholecystokinin (CCK) which results in intraluminal accumulation of water, electrolytes and increased intestinal motility. This stimulates the nerves of the colon to distend leading to peristalsis culminating in the evacuation of its contents.

===Plaster of Paris===

===Plaster of Paris===

===Alkaline Water===

===Alkaline Water===

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UNN_Medical_Geology_Fig_18.png|{{figure number|18}}Increase in pH due to alkaline water intake<ref name=TK>Tan Koon, P. M., 2013, [www.alkaflask.blogspot.sg  AlkaFlask Potable Alkaline Water Maker].</ref>

UNN_Medical_Geology_Fig_18.png|{{figure number|18}}Increase in pH due to alkaline water intake<ref name=TK>Tan Koon, P. M., 2013, [http://alkaflask.blogspot.com/ AlkaFlask Potable Alkaline Water Maker].</ref>

UNN_Medical_Geology_Fig_19.png|{{figure number|19}}Arrangement of different geologic materials in the alkaline water flask.<ref name=TK>

UNN_Medical_Geology_Fig_19.png|{{figure number|19}}Arrangement of different geologic materials in the alkaline water flask.<ref name=TK>

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