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Minor elements are those elements that are needed in moderate quantities; each has a concentration of 0.1% to 1.0% in the body (Selinus et al, 2013). They share in the functions of the major elements, but in smaller amounts.

Minor elements are those elements that are needed in moderate quantities; each has a concentration of 0.1% to 1.0% in the body (Selinus et al, 2013). They share in the functions of the major elements, but in smaller amounts.

Trace elements are those elements that have concentrations far below 0.1% in the body; they are needed in the body only in parts per million (ppm). They are essential to plant and animal lives only in trace amounts. Such trace elements are called essential trace elements.<ref>Christine, L. E., G. Sujuan, L. Yiming, L. Chaoke, J. Rongdi, S. H. Kathleen, C. Jingxiang, M. Feng, W. Yunpeng, Y. Po, S. Shuzhuang, W. U. Frederick, W. S. Charles, and C. H. Hugh, 2000, Trace Element Levels in Drinking Water and Cognitive Function among Elderly Chinese: American Journal of Epidemiology, 151(9), 913-920.</ref> They are highly variable in their abundance in various rocks (Table 1, Khandare, 2012 ).

Trace elements are those elements that have concentrations far below 0.1% in the body; they are needed in the body only in parts per million (ppm). They are essential to plant and animal lives only in trace amounts. Such trace elements are called essential trace elements.<ref>Christine, L. E., G. Sujuan, L. Yiming, L. Chaoke, J. Rongdi, S. H. Kathleen, C. Jingxiang, M. Feng, W. Yunpeng, Y. Po, S. Shuzhuang, W. U. Frederick, W. S. Charles, and C. H. Hugh, 2000, Trace Element Levels in Drinking Water and Cognitive Function among Elderly Chinese: American Journal of Epidemiology, 151(9), 913-920.</ref> They are highly variable in their abundance in various rocks (Table 1).

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|+ Table 1: Average abundances of selected elements in bedrock, all values in ppm ( after Khandare, 2012).

|+ Table 1: Average abundances of selected elements in bedrock, all values in ppm.<ref name=Khndare>Khandare, H. W., 2012, Medical Geology: An Emerging Field of Interdisciplinary Research on Geology and Human Health. International Journal of ChemTech Research CODEN (USA), 4(4), 1792-1796.</ref>

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! Element !! Ultrabasic Rock !! Basalt !! Granite !! Shale !! Limestone

! Element !! Ultrabasic Rock !! Basalt !! Granite !! Shale !! Limestone

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|+ Table 2: Diseases caused by the deficiencies and excessiveness/toxicity of some trace elements (after Khandare, 2012).

|+ Table 2: Diseases caused by the deficiencies and excessiveness/toxicity of some trace elements.<ref name=Khndare />

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! Element || Deficiency || Excessiveness/Toxicity

! Element || Deficiency || Excessiveness/Toxicity

'''Geochemistry of Arsenic:''' Arsenic is a metalloid and has high affinity for sulphide-bearing minerals. One of such minerals is pyrite, hence the formation of arsenopyrite (FeAsS). In the tropics, oxidative weathering leads to the formation Arsenite (As3+) and Arsenate (As4+).<ref name=Adeyinka>Adeyinka, O., N. M. Miranda, P. T. Raymond, Y. Abubakar, and C. A. Edafetano, 2013, Arsenic in Rocks of Kaltungo Area, Upper Benue Trough, Nigeria. Earth Resources, 1(1), 5-11.</ref>

'''Geochemistry of Arsenic:''' Arsenic is a metalloid and has high affinity for sulphide-bearing minerals. One of such minerals is pyrite, hence the formation of arsenopyrite (FeAsS). In the tropics, oxidative weathering leads to the formation Arsenite (As3+) and Arsenate (As4+).<ref name=Adeyinka>Adeyinka, O., N. M. Miranda, P. T. Raymond, Y. Abubakar, and C. A. Edafetano, 2013, Arsenic in Rocks of Kaltungo Area, Upper Benue Trough, Nigeria. Earth Resources, 1(1), 5-11.</ref>

'''Mechanism of Toxicity:''' Due to its affinity for sulphur, arsenic in biological systems, attacks sulphur-bearing enzymes by binding and blocking them. Soon, it makes its way through the digestive tract to the liver, spleen and lungs. Although most arsenic is excreted, some are still retained in the skin, hair, legs, nails and teeth.<ref name=Fnklman2010a>Finkelman, R. B., H. E. Belkin, and B. Zheng, 2010a, Health Impacts of Domestic Coal Use in China: Proceedings National Academy of Science, (USA), 96, 3427-3431.</ref> As the concentration increases, adverse health effects result leading to carcinogenic or non-cancer problems. Prolonged exposure to arsenic induces peripheral arteriosclerosis, hair fall-out, retarded nail growth and various types of skin conditions such as hyperkeratosis, hyper- pigmentation and skin malignancies. These levels of disorders are prominent in places with arsenic concentrations of 100−1000μg/l in their groundwater as against 50μg/l stipulated by WHO in 1993 (Hutton, 1987). However, the presence of selenium reduces the toxic effects of arsenic.

'''Mechanism of Toxicity:''' Due to its affinity for sulphur, arsenic in biological systems, attacks sulphur-bearing enzymes by binding and blocking them. Soon, it makes its way through the digestive tract to the liver, spleen and lungs. Although most arsenic is excreted, some are still retained in the skin, hair, legs, nails and teeth.<ref name=Fnklman2010a>Finkelman, R. B., H. E. Belkin, and B. Zheng, 2010a, Health Impacts of Domestic Coal Use in China: Proceedings National Academy of Science, (USA), 96, 3427-3431.</ref> As the concentration increases, adverse health effects result leading to carcinogenic or non-cancer problems. Prolonged exposure to arsenic induces peripheral arteriosclerosis, hair fall-out, retarded nail growth and various types of skin conditions such as hyperkeratosis, hyper- pigmentation and skin malignancies. These levels of disorders are prominent in places with arsenic concentrations of 100−1000μg/l in their groundwater as against 50μg/l stipulated by WHO in 1993.<ref name=Htton>Hutton, M., 1987, Human Health Concerns of Lead, Mercury, Cadmium and Arsenic. John Wiley & Sons Ltd, Uk, 68p.</ref> However, the presence of selenium reduces the toxic effects of arsenic.

In Nigeria, high concentrations of arsenic have been confirmed in the Northern Benue Trough in the Kaltungo area of Gombe State. Arsenic in this area emanates from coarse porphyritic granite, biotite granite, Bima Sandstone and basalt.<ref name=Adeyinka /> Arsenic was determined using Inductively Coupled Plasma Optical Emission Spectrophotometer (ICPOES), Optima 2000 DV, at the Petroleum Technology Development Fund (PTDF) Geochemistry Laboratory of Department of Geology and Mining, University of Jos. The arsenic concentrations tend to follow the same northeast- southwest trend as the Benue Trough. High concentration of arsenic in this area is attributed to the mid-Santonian magmatism in the Benue Trough.<ref name=Adeyinka />

In Nigeria, high concentrations of arsenic have been confirmed in the Northern Benue Trough in the Kaltungo area of Gombe State. Arsenic in this area emanates from coarse porphyritic granite, biotite granite, Bima Sandstone and basalt.<ref name=Adeyinka /> Arsenic was determined using Inductively Coupled Plasma Optical Emission Spectrophotometer (ICPOES), Optima 2000 DV, at the Petroleum Technology Development Fund (PTDF) Geochemistry Laboratory of Department of Geology and Mining, University of Jos. The arsenic concentrations tend to follow the same northeast- southwest trend as the Benue Trough. High concentration of arsenic in this area is attributed to the mid-Santonian magmatism in the Benue Trough.<ref name=Adeyinka />

Chemical and mineralogical tests conducted showed that there were many arsenic-bearing minerals in the coals, although, much of the arsenic is bound to the organic matrix of the coals. This observation presented two problems namely: (1) since arsenic is bound to the organic matrix, conventional reduction methods of removing arsenic was ineffective; (2) the visually observable pyrite on the coal samples was not reliable in establishing arsenic-rich samples.

Chemical and mineralogical tests conducted showed that there were many arsenic-bearing minerals in the coals, although, much of the arsenic is bound to the organic matrix of the coals. This observation presented two problems namely: (1) since arsenic is bound to the organic matrix, conventional reduction methods of removing arsenic was ineffective; (2) the visually observable pyrite on the coal samples was not reliable in establishing arsenic-rich samples.

This caused an outbreak of various kinds of arsenosis resulting from arsenic poisoning with typical symptoms as shown in the Table 3 below and [[:File:UNN_Medical_Geology_Fig_5.png|Figure 5]]. (Hutton, 1987)

This caused an outbreak of various kinds of arsenosis resulting from arsenic poisoning with typical symptoms as shown in the Table 3 below and [[:File:UNN_Medical_Geology_Fig_5.png|Figure 5]].<ref name=Htton />

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|+ Table 3: Effects of Arsenic at various organs (Hutton, 1987).

|+ Table 3: Effects of Arsenic at various organs.<ref name=Htton />

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! Organ Affected || Effects

! Organ Affected || Effects

Cadmium has great affinity for sulphides and is therefore associated with sulphide deposits. It has very similar tetrahedral covalent radius to that of zinc; thus, it can displace zinc from sphalerite (ZnS).

Cadmium has great affinity for sulphides and is therefore associated with sulphide deposits. It has very similar tetrahedral covalent radius to that of zinc; thus, it can displace zinc from sphalerite (ZnS).

Cadmium is highly toxic to humans. According to Hutton (1987), it mainly accumulates in soft tissues such as the kidneys and liver. In Japan, it is the cause of a disease known as itai-itai–a disease that affects mainly women.<ref name=Hisashi>Hisashi, N., F. Kunio, and K. Takashi, 2010, Medical Geology in China. In: Selinus, O., Finkelman, R.B. and Centeno, J.A., eds, Medical Geology: A Regional Synthesis, 329–338.</ref> Its symptoms include: backaches, pain in the limbs, arthralgia and pain in the pubic bones. This is the direct result of the loss of calcium in bones. The loss makes the bones to be fragile and causes the development of fractures. The victim remains in pain until death. In a particular autopsy conducted, 72 fracture points were seen.<ref name=Hisashi />

Cadmium is highly toxic to humans. According to Hutton,<ref name=Htton /> it mainly accumulates in soft tissues such as the kidneys and liver. In Japan, it is the cause of a disease known as itai-itai–a disease that affects mainly women.<ref name=Hisashi>Hisashi, N., F. Kunio, and K. Takashi, 2010, Medical Geology in China. In: Selinus, O., Finkelman, R.B. and Centeno, J.A., eds, Medical Geology: A Regional Synthesis, 329–338.</ref> Its symptoms include: backaches, pain in the limbs, arthralgia and pain in the pubic bones. This is the direct result of the loss of calcium in bones. The loss makes the bones to be fragile and causes the development of fractures. The victim remains in pain until death. In a particular autopsy conducted, 72 fracture points were seen.<ref name=Hisashi />

Health issues arising from high cadmium concentration has also been established in the central parts of Jamaica ([[:File:UNN_Medical_Geology_Fig_8.png|Figure 8]]). It occurs in the soil of a region with limestone and an overlying aluminum-rich bauxite deposit (Wright et al, 2010). Cadmium exists in a phosphatic band that forms the interface between the two lithologies. Further research indicates that the phosphatic band contains fossilized fish bones and teeth suggesting a marine origin. The processes of weathering release cadmium from the phosphatic band into the soil.

Health issues arising from high cadmium concentration has also been established in the central parts of Jamaica ([[:File:UNN_Medical_Geology_Fig_8.png|Figure 8]]). It occurs in the soil of a region with limestone and an overlying aluminum-rich bauxite deposit (Wright et al, 2010). Cadmium exists in a phosphatic band that forms the interface between the two lithologies. Further research indicates that the phosphatic band contains fossilized fish bones and teeth suggesting a marine origin. The processes of weathering release cadmium from the phosphatic band into the soil.

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 (Knishinsky, 1998).

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>

===Kaolin===

===Kaolin===

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* Ljung, K., de Vos, A., Cook, A. and Weinstein, P., 2010. An Overview of Medical Geology Issues in Australia and Oceania. In: Selinus, O., Finkelman, R.B. and Centeno, J., (Eds), 2010. Medical Geology – A Regional Synthesis. Springer, Germany, 107-135.

* Ljung, K., de Vos, A., Cook, A. and Weinstein, P., 2010. An Overview of Medical Geology Issues in Australia and Oceania. In: Selinus, O., Finkelman, R.B. and Centeno, J., (Eds), 2010. Medical Geology – A Regional Synthesis. Springer, Germany, 107-135.

* Nghargbu, K., Ponikowska, I., Latour, T., Kurowska, E., Schoeneich, K., and Alagbe, S.A., 2013. Balneo-therapeutic Quality of Water from Thermal Chlorosodic Springs of the Middle Benue Trough, Nigeria. Unpublished Work, Nasarawa State University, Keffi, Nigeria,1-9.

* Nghargbu, K., Ponikowska, I., Latour, T., Kurowska, E., Schoeneich, K., and Alagbe, S.A., 2013. Balneo-therapeutic Quality of Water from Thermal Chlorosodic Springs of the Middle Benue Trough, Nigeria. Unpublished Work, Nasarawa State University, Keffi, Nigeria,1-9.