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Medical geology achieves these goals through a coordinated effort by various professionals from geology, geography, biochemistry and medical sciences.

Medical geology achieves these goals through a coordinated effort by various professionals from geology, geography, biochemistry and medical sciences.

In essence, ''medical geology is a multidisciplinary field of study in geology which studies the health effects of geological materials and processes on humans and animals with both good and, possibly, hazardous results.'' The Commission on Geological Sciences for Environmental Planning defines medical geology as, "the science dealing with the influence of ordinary environmental factors on the geographical distribution of health problems in man and animals." The goal of this field is to find the right balance and intake of elements/minerals in order to improve and maintain health (Finkelman et al, 2005).

In essence, ''medical geology is a multidisciplinary field of study in geology which studies the health effects of geological materials and processes on humans and animals with both good and, possibly, hazardous results.'' The Commission on Geological Sciences for Environmental Planning defines medical geology as, "the science dealing with the influence of ordinary environmental factors on the geographical distribution of health problems in man and animals." The goal of this field is to find the right balance and intake of elements/minerals in order to improve and maintain health<ref name=Fnklman2005>Finkelman, R. B., J. A. Centeno, and O. Selinus, 2005, The Emerging Medical and Geological Associations: Transactions of the American Clinical and Climatological Association, 116, 155-165.</ref>

According to Finkelman et al (2005), the range and scope of medical geology include:

According to Finkelman et al,<ref name=Fnklman2005 /> the range and scope of medical geology include:

# Identifying and characterizing natural sources of harmful materials in the environment using geosciences techniques;

# Identifying and characterizing natural sources of harmful materials in the environment using geosciences techniques;

# The study of trace elements, especially their bioavailability;

# The study of trace elements, especially their bioavailability;

===Environment and our health===

===Environment and our health===

[[File:UNN_Medical_Geology_Fig_2.png|thumb|400px|{{figure number|2}}Geologic cross-section of the Pikes Peak area showing the sources of fluoride in the Colorado Spring (Finkelman et al, 2010b).]]

[[File:UNN_Medical_Geology_Fig_2.png|thumb|400px|{{figure number|2}}Geologic cross-section of the Pikes Peak area showing the sources of fluoride in the Colorado Spring.<ref name=Fnklman2010b>Finkelman, R. B., H. Gingerich, J. A. Centeno, and G. Krieger, 2010b, Medical Geology Issues in North America, in O. Selinus, B. Alloway, J. A. Centeno, R. B. Finkelman, R. Fuge, U. Lindh, and P. Smedley, eds., Essentials of Medical Geology. Elsevier, Amsterdam, 1-9.</ref>]]

Over the years, it has been observed that the environment man lives in affects his health. For instance, the people of Maputaland, South Africa, are plagued by nutrient-poor soil. Maize grown in this region has very low content of elements such as calcium, potassium and phosphorous (Selinus and Frank, 2000). This is as a result of low concentration of these elements in the rocks of that region. Countries in southern Africa also suffer from selenium deficiency in their soils. This accounts for the spread of HIV-1 virus in this zone as selenium which inhibits the replication of HIV-1 is lacking in their soil. Still in Africa, Kerala Province in Uganda is another region under the “hammer” of geology. Children in this province suffer from a ‘grave’ coronary heart condition called endomyocardial fibrosis (EMF). This epidemic is attributed to the deliberate eating of soil containing the element cerium.<ref name=Dvies>Davies, T. C., 2010. Medical Geology in Africa, ''in'' O. Selinus, R. B. Finkelman, and J. A. Centeno, eds., Medical Geology: A Regional Synthesis, 199–216.</ref>

Over the years, it has been observed that the environment man lives in affects his health. For instance, the people of Maputaland, South Africa, are plagued by nutrient-poor soil. Maize grown in this region has very low content of elements such as calcium, potassium and phosphorous (Selinus and Frank, 2000). This is as a result of low concentration of these elements in the rocks of that region. Countries in southern Africa also suffer from selenium deficiency in their soils. This accounts for the spread of HIV-1 virus in this zone as selenium which inhibits the replication of HIV-1 is lacking in their soil. Still in Africa, Kerala Province in Uganda is another region under the “hammer” of geology. Children in this province suffer from a ‘grave’ coronary heart condition called endomyocardial fibrosis (EMF). This epidemic is attributed to the deliberate eating of soil containing the element cerium.<ref name=Dvies>Davies, T. C., 2010. Medical Geology in Africa, ''in'' O. Selinus, R. B. Finkelman, and J. A. Centeno, eds., Medical Geology: A Regional Synthesis, 199–216.</ref>

China is not left aside in these problems. The country suffers from deficiencies and excessiveness of selenium in many parts of the country resulting in life-threatening health problems. China also suffers from the influx of arsenic into coal deposits whose domestic use has resulted to untold chronic health effects over the years (Skinner, 2007).

China is not left aside in these problems. The country suffers from deficiencies and excessiveness of selenium in many parts of the country resulting in life-threatening health problems. China also suffers from the influx of arsenic into coal deposits whose domestic use has resulted to untold chronic health effects over the years (Skinner, 2007).

The use of water from the Colorado Springs at the Pikes Peak in the Rocky Mountain region of USA had led to dental fluorosis amongst children. This condition arose as a result of meteoric waters that flowed over faulted granitic batholiths (Finkelman et al, 2010b). The meteoric waters ‘picked up’ fluoride from easily dissolved minerals at the fault and incorporated it into the flow. Fluoride was also injected into the Colorado Springs by fluoride-enriched fractured and faulted Cretaceous Pierre Shale that underlies the spring ([[:File:UNN_Medical_Geology_Fig_2.png|Figure 2]], Finkelman et al, 2010b).

The use of water from the Colorado Springs at the Pikes Peak in the Rocky Mountain region of USA had led to dental fluorosis amongst children. This condition arose as a result of meteoric waters that flowed over faulted granitic batholiths.<ref name=Fnklman2010b /> The meteoric waters ‘picked up’ fluoride from easily dissolved minerals at the fault and incorporated it into the flow. Fluoride was also injected into the Colorado Springs by fluoride-enriched fractured and faulted Cretaceous Pierre Shale that underlies the spring ([[:File:UNN_Medical_Geology_Fig_2.png|Figure 2]]).

===Biological classification of elements===

===Biological classification of elements===

'''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 (Finkelman et al, 2010a). 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 (Hutton, 1987). 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 />

Arsenosis refers to a range of adverse health effects caused by the intake of arsenic into the body system above the recommended values of 50μg/l.

Arsenosis refers to a range of adverse health effects caused by the intake of arsenic into the body system above the recommended values of 50μg/l.

In Guizhou Province, China, the cool, damp autumn weather forces villagers to bring their harvest of chili peppers and corn indoors to dry. They hang the peppers over unvented stoves which were formally fueled by wood. But, due to the destruction of forests, wood became scarce; so, the villagers turned to the plentiful outcrops of coal for heating, cooking and drying their harvests (Finkelman et al, 2010a). Unknowingly to them, mineralizing solutions in this area had deposited enormous concentrations of arsenic − up to 35,000 ppm − and other trace elements on the coals. It should be noted that normal coals have arsenic concentration of 20 ppm. Consumption of the chili peppers dried over these arsenic-rich coals exposed the natives to arsenosis. The dried chili peppers contained up to 500 ppm of arsenic whereas normal chili peppers contain less than 1 ppm of arsenic (Wuyi et al, 2003). In addition, inhalation of arsenic-laden indoor air derived from coal combustion has increased the toll of arsenic poisoning in the region (Finkelman, 2005).

In Guizhou Province, China, the cool, damp autumn weather forces villagers to bring their harvest of chili peppers and corn indoors to dry. They hang the peppers over unvented stoves which were formally fueled by wood. But, due to the destruction of forests, wood became scarce; so, the villagers turned to the plentiful outcrops of coal for heating, cooking and drying their harvests.<ref name=Fnklman2010a /> Unknowingly to them, mineralizing solutions in this area had deposited enormous concentrations of arsenic − up to 35,000 ppm − and other trace elements on the coals. It should be noted that normal coals have arsenic concentration of 20 ppm. Consumption of the chili peppers dried over these arsenic-rich coals exposed the natives to arsenosis. The dried chili peppers contained up to 500 ppm of arsenic whereas normal chili peppers contain less than 1 ppm of arsenic (Wuyi et al, 2003). In addition, inhalation of arsenic-laden indoor air derived from coal combustion has increased the toll of arsenic poisoning in the region.<ref name=Fnklman2005 />

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.

===Health effects of radon gas===

===Health effects of radon gas===

[[File:UNN_Medical_Geology_Fig_10.png|thumb|400px|{{figure number|10}}Various pathways through which radon gas can migrate to the surface and into buildings (Finkelman et al, 2010b).]]

[[File:UNN_Medical_Geology_Fig_10.png|thumb|400px|{{figure number|10}}Various pathways through which radon gas can migrate to the surface and into buildings.<ref name=Fnklman2010b />]]

Radon is a colourless inert gas formed from the radioactive disintegration of radium –the radioactive daughter of uranium. It has been established that there is a link between the levels of radon emitted by the rocks and that emitted by soils. The level of radon emitted by any rock depends on the quantity of uranium it contains which occurs in association with other minerals such as gold, phosphate and copper. This explains the scourge of lung cancer amongst uranium miners, as radon is carcinogenic. Radon emitted from most rocks travel to the surface through fractures and faults (Finkelman et al, 2010b). Its movement into buildings occurs through foundation cracks, cracks in the floor and walls below and above the surface. It can also enter through gaps in timber floors and around pipe fittings ([[:File:UNN_Medical_Geology_Fig_10.png|Figure 10]]).

Radon is a colourless inert gas formed from the radioactive disintegration of radium –the radioactive daughter of uranium. It has been established that there is a link between the levels of radon emitted by the rocks and that emitted by soils. The level of radon emitted by any rock depends on the quantity of uranium it contains which occurs in association with other minerals such as gold, phosphate and copper. This explains the scourge of lung cancer amongst uranium miners, as radon is carcinogenic. Radon emitted from most rocks travel to the surface through fractures and faults.<ref name=Fnklman2010b /> Its movement into buildings occurs through foundation cracks, cracks in the floor and walls below and above the surface. It can also enter through gaps in timber floors and around pipe fittings ([[:File:UNN_Medical_Geology_Fig_10.png|Figure 10]]).

African countries that have uranium as a natural resource include: South Africa which has the largest deposit of uranium in the continent–241,000 metric tons, Niger, Namibia, Gabon, Algeria, Botswana, Central African Republic, Chad. Others are: Egypt, Nigeria, Morocco, Mali, Madagascar, Malawi, Togo, Tanzania, Mauritania, Somalia, Guinea, Zambia and Lesotho.<ref name=Dvies />

African countries that have uranium as a natural resource include: South Africa which has the largest deposit of uranium in the continent–241,000 metric tons, Niger, Namibia, Gabon, Algeria, Botswana, Central African Republic, Chad. Others are: Egypt, Nigeria, Morocco, Mali, Madagascar, Malawi, Togo, Tanzania, Mauritania, Somalia, Guinea, Zambia and Lesotho.<ref name=Dvies />

==References==

==References==

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* Fordyce, F., 2010. Selenium Deficiency and Toxicity in the Environment. In: Selinus, O., Alloway, B., Centeno, J.A., Finkelman, R.B., Fuge, R., Lindh, U. and Smedley, P., (eds.) 2010. Essentials of Medical Geology. Elsevier, Amsterdam, 375-413.

* Fordyce, F., 2010. Selenium Deficiency and Toxicity in the Environment. In: Selinus, O., Alloway, B., Centeno, J.A., Finkelman, R.B., Fuge, R., Lindh, U. and Smedley, P., (eds.) 2010. Essentials of Medical Geology. Elsevier, Amsterdam, 375-413.

* Fuge, R., 2010. Soils and Iodine Deficiency. In: Selinus, O., Alloway, B., Centeno, J.A., Finkelman, R.B., Fuge, R., Lindh, U. and Smedley, P., (eds.) 2010. Essentials of Medical Geology. Elsevier, Amsterdam: 417-433.

* Fuge, R., 2010. Soils and Iodine Deficiency. In: Selinus, O., Alloway, B., Centeno, J.A., Finkelman, R.B., Fuge, R., Lindh, U. and Smedley, P., (eds.) 2010. Essentials of Medical Geology. Elsevier, Amsterdam: 417-433.