Medical geochemistry of tropical environments

Dissanayake, C.B.; Chandrajith, Rohana

doi:10.1016/s0012-8252(99)00033-1

Cited by 97 publications

(48 citation statements)

References 84 publications

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“…Studies from several other countries of the tropical belt have clearly shown the importance of groundwater fluoride as a major risk factor for kidney diseases (Bober et al, 2006;Chandrajith et al, 2011a;Chandrajith et al, 2011b;Chouhan and Flora, 2008). The geochemical significance of some diseases in tropical countries have been highlighted by Dissanayake and Chandrajith (1999) and they have shown that some diseases such as dental and skeletal fluorosis, iodine deficiency disorders, selenium-related diseases among others could also be classified as diseases of -geochemical origin‖. The new discipline -Medical Geology‖ therefore is of particular importance to tropical countries where extremely large populations live intimately associated with the immediate physical environment with their unique geochemical characteristics.…”

Section: Introductionmentioning

confidence: 99%

Groundwater fluoride as a geochemical marker in the etiology of chronic kidney disease of unknown origin in Sri Lanka

Dissanayake

Chandrajith

2017

Ceylon J. Sci.

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Section: Introductionmentioning

confidence: 99%

Groundwater fluoride as a geochemical marker in the etiology of chronic kidney disease of unknown origin in Sri Lanka

Dissanayake

Chandrajith

2017

Ceylon J. Sci.

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“…Marine carbonate and sedimentary rocks contain iodine ranging from 2.5 to 30 ppm (Dissanayake and Chandrajith, 1999). Ground and surface waters are among the most important media that act as a bridge between rock, rainwater and soil geochemistry and human physiology (Dissanayake and Chandrajith, 1999).…”

Section: Geo-environmental Sources Of Iodinementioning

confidence: 99%

“…In other tropical settings, heavy monsoon rains generally contain higher iodine content leading to lower prevalence of goiter (Dissanayake and Chandrajith, 1999). The heavy monsoon rain in south-western lowlands and mid-altitude regions of Ethiopia derives part of its moisture from continental setting such as the Congo vegetation.…”

Section: Geo-environmental Model Of Geo-chemical Diseases In Ethiopiamentioning

confidence: 99%

The linkage between geological setting and human health in Ethiopia: a preliminary geo-environmental-health model

Kebede

2011

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ABSTRACT:Tropical environments are known for their prevalence of a number of geo-chemical diseases. This is related to the very nature of their geo-environments. Little research is conducted in geo-sciences in Ethiopia to investigate the linkage between geo-environments and associated health risks. Fluoride and related diseases are the most widely studied from geological perspectives. Ethiopia is characterized by complex but regionally homogeneous geo-environment. Climate is under the influence of monsoon from two oceans and continental sources. Locally orography modifies the redistribution of rainfall in the lee and wind ward directions. This leads to any combination of warm to cold and wet to dry climate. Prominent geologic features are rifting, volcanism and uplifting. Combination of geology, climate, and topography results in a complex pattern of geo-environment which in turn results in belts of availability or scarcity of certain geochemical elements. This work shows the presence of linkage between geo-environmental setting and prevalence of geo-chemical diseases such as goiter, elephantiasis, flourisis, and trace element related health problems. South-western Ethiopia, which is under the influence of Indian Ocean monsoon and underlain by volcanic rocks shows the highest incidence of Iodine Deficiency Disorder (IDD). Regions of Ethiopia under the influence of Atlantic Ocean monsoon or areas underlain by sediments and sedimentary rocks show the lowest IDD. Elephantiasis prevalence is linked to laterite soils derived from chemical weathering of basalts, a typical process commonly taking place in humid plateau of south-western Ethiopia between altitudes of 1000 and 2000 masl. Flouride related diseases are common features in area where water supply for domestic water use depend on aquifers in acid volcanic rocks, commonly in the rift setting. Regardless of the prevalence of geo-chemical diseases, Ethiopia is also endowed with natural geo-chemical materials of significant health benefits (e.g., Mineral waters and mud volcanoes). The work proposes a preliminary geo-environmental health model for Ethiopia.

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“…Indeed, a study using a geo-environmental perspective may have yielded a better understanding of the occurrence, transfer processes and the potentials of thallium related environmental hazard due to natural processes and human perturbation in the geosphere and biosphere, and the effective means of remediation. Even in the geoscience literature, many researchers neglected thallium as a toxic element in the classification of toxic/non-toxic elements (Plant and Raiswell, 1987;Edmunds and Smedley, 1996;Dissanayake and Chandrajith, 1999). In this respect, it seems that in the field of geo-environmental studies, thallium as an issue lags far behind when compared to the fields of medicine and biology.…”

Section: Mise En Garde/advicementioning

confidence: 99%

Environmental impact of thallium related to the mercury-thallium-gold mineralization in southwest Guizhou Province China

Xiao¹

2001

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Toxic metals associated with metal mineralization and mining are critical targets for environmental studies. Thallium, as a typical toxic metal, has received less attention from a geo-environmental perspective since thallium deposits are relatively rare.This study focuses on natural accumulation of thallium associated with Hg-Tl-(Au) mineralization in the Lanmuchang area in southwest Guizhou Province, China, as a case study for thallium hazard in a geo-environmental perspective. It aims at understanding of the occurrence, the transfer processes and the environmental impacts of thallium related to natural processes and human activity. The distribution and dispersion of thallium together with mercury and arsenic in bedrock, sulfide ore, coals, soil, sediment, ground and surface waters, crops and vegetation have been examined.This study shows that the Lanmuchang area can be characterized as a specific geological context of thallium, mercury and arsenic accumulations. The extensive occurrences of sulfide minerals, such as lorandite, cinnabar, realgar, orpiment and pyrite are the primary carriers of Tl, Hg and As in the rocks and ores. Thallium occurs either as isomorphous substitution in the structure of sulfide minerals of mercury ores, arsenic ores coals, or as a pure thallium mineral lorandite.Tl, Hg and As accumulations are characterized by their high concentrations in rocks/ores, soils, sediments, (sub)surface waters and various crops. The range of thallium concentrations are 33-35000 ppm in sulfide ores, 12-46 ppm in coals, 33-490 ppm in host rocks, 25-1100 ppm in secondary minerals, and 6-330 ppm in outcropped host rocks. Thallium concentrations in soils in the mineralized area range from 53 to 282 ppm, from 21 to 100 ppm in alluvial deposits or foundation soils, from 40 to 46 ppm in slope wash material, and from 2.2 to 29 ppm in undisturbed natural soil. A high concentration has also been observed in sediments, ranging from 10 to 3700 ppm. Thallium concentrations are also high in the deep groundwater of the thallium-mineralized area (13.4-1102 \lg/\), decreasing away from the area to a background level of less than 0.005 |ig/l. In stream water, thallium concentration ranges from 0.3 to 33 jig/1, with marked high contents in downstream sections which likely originated from an unidentified groundwater discharge. In the edible parts of various vegetables and cereals, thallium ranges from 0.21 to 494 ppm (dry weight). The uptake of thallium is more pronounced in vegetables than in cereals, and the highest accumulation occurs in green cabbage.The dispersion of thallium together with mercury and arsenic in the specific ecosystem of Lanmuchang is constrained by the original Tl-Hg-As sulfide mineralization, the specific topography and hydro-geomorphology, and by the disturbance of human activity. High values of thallium are concentrated in the mineralized and mining area; away from this area, thallium concentrations decreases gradually to a background level. Thallium from bedrocks is accumulated in soils, se...

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Medical geochemistry of tropical environments

Cited by 97 publications

References 84 publications

Groundwater fluoride as a geochemical marker in the etiology of chronic kidney disease of unknown origin in Sri Lanka

Groundwater fluoride as a geochemical marker in the etiology of chronic kidney disease of unknown origin in Sri Lanka

The linkage between geological setting and human health in Ethiopia: a preliminary geo-environmental-health model

Environmental impact of thallium related to the mercury-thallium-gold mineralization in southwest Guizhou Province China

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