Introduction to Geo-medicine

1. Introduction to Geo-medicine

2. Module Name: Introduction to Geo-medicine Module Code: MEG 2643 Lecture Notes • Lecturer: Ms Mundalamo Department of Mining and Environmental Geology School of Environmental Geology University of Venda

3. Outline • What is Geomedicine? Definition and Concept • Periodic table of elements – Revision • Principal chemical constituents of the human body • Essential elements in life systems • Control on elemental intake • Toxic elements • Sources of toxic elements • Bioavailability of toxic elements to bioreceptors • Pathways of toxic elements in soils , plants and animal systems • Dose-response curves • The changing nature of disease • Health effects of excess/deficiency of selenium, lead. mercury, zinc, cadmium and arsenic • Investigation of casual links between specific diseases and the geological environment • Geogenic sources of atmospheric particulates • Dust emission in mining and mineral processing and the fate of inhaled particles • Chronic Bronchitis • Allergic lung disease • Coal workers pneumoconiosis • Asbestosis • Cancer and mutagens • Silicosis

4. Outline • Geological aspects of waste disposal including radioactive waste • Ionization and radon gas • Balneology of peat deposits • Health spas and mineral waters • Geochemical maps in medical geology • Environmental data sources • Medical data sources • Data analysis using Pearson’s correlation • Use of remote sensing and GIS in human health studies • Analytical techniques in environmental Geochemistry • Geochemical Data bases

5. Projects • Berylliosis Group A • Talcosis Group B • Siderosis Group C • Geophagia Group D • Podoconiosis and Kaposis’s sarcoma Group E

6. References • Author Komatina, Miomir M. Medical geology : effects of geological environments on human health Publisher Amsterdam, The Netherlands : Elsevier, 2004. • Medical Geology : A regional Synthesis • Closing the Gap

7. What is Geomedicine? • - Geomedicine, often referred to as Medical Geology, is upcoming discipline that links earth sciences and medicine. • - It is the science that investigates the effects of the presence or absence of trace elements in organisms. • - The discipline tries to establish casual links between specific diseases in human, animals and plants and geological processes and human activities in space and time. • - The study of geomedicine includes industrially derived exposure to known toxic elements originating from mining and mineral processing.

8. What is Geomedicine? • - Geomedicine is a multidisciplinary subject, which requires cooperation among geologists, clinicians, epidemiologists, biologists, veterinarians etc. • - The role of geologist is to help isolate geological aspects that might influence the incidence of diseases. • - Medical Geology has acquired its present status due partly to inter–disciplinary approaches in solving scientific problems and partly to advances in analytical methodology, enabling the determination of nutritional trace elements at lower detection levels (ppm/ppb) • - Trace elements are important not only for their deficiency, but also for their excess. Besides such elements such as As, F, Se, Pb, Zn, Fe, Mo can cause severe consequences in circumstances of natural chronic poisoning.

9. What is Geomedicine? • - Both, Acute and Chronic toxicity have to be considered. • - Deficiencies, excess or imbalances in the supply of inorganic elopements from dietary sources can have an important influence on human and animal health. • - Such situations arise mainly from anomalies in the inorganic elements composition of food chains, which are frequently attributed to the composition of the geochemical environment as modified by the influence of soil composition and bacterial variables.

10. Why this new discipline? • Create awareness of, and concern for the environment during the exploitation of natural resources • Develop concepts and skills for assessing and resolving environmental issues, questions and problems related to mining and mineral processing • Introduce a firm background in professional expertise and environmental principles in research and development activities in society, leading to improved methodologies and techniques for mitigation • Promote participation in practical environmental activities with a view to enhancing environmental quality in the lives of local communities.

11. Why this new discipline? • Improve communication amongst the various disciplines concerned with diseases caused by geological factors which influence the well being of man and minerals • Developed information material for the use of schools, publics and private organisation interested in these fields to show the impact of geologic factors on well being of man and animals. • Encourage geological surveys, universities, and geological societies to take a more active role in providing useful information on geologic conditions in Geoscience and health problems. • Encourage the development of local working groups of multi-disciplinary Geomedicine, Geoscientists, Geo environment and health expect • Encourage research in the area of producing more effective methodologies for the study of geological factors in environment medicine

12. Essential elements in life systems • Essential elements are all those elements which are of great importance in life system. That is in plants animals and humans. • These essential elements are further classified into • major elements/macro elements and • trace elements/microelements.

13. Major elements • Are those which are needed most in life system. • More than 99% of human body is made of the six major elements: O, C, H, N, Ca, and P. • Human body is about 60% water. The rest: • protein, fat, carbohydrates containing: O, C, H, N, Ca, and P • Teeth and bone: Ca, O, P, H

14. Major elements • Dissolve salts: K, Na, Mg, Ca, Cl, Br, I, C, O, P • Major elements of the human body are obviously critical to life and health. • Thus most part of the Geomedicine is the study of the effects of the presence or absence of the trace elements

15. Trace elements • Trace elements are those found in concentrations of about 10 to 100 ppm or less. • The essential trace elements are required in small amounts for proper functioning of various enzyme system • These elements can have quite different effects, depending on the concentration in which it occurs or consumed. • That is effects such as acute or chronic toxicity.

16. Toxic elements • Elements which have effects at very low concentration • These elements often replace trace elements in the body, but get stuck where they are and shut down the essential function • Example: • Cd, Hg: replace Zn, C u • Sr, Ba: replace Ca • As, Sb: replace P • Se, Te replace S • W replace Cr, Mo

17. Non essential elements • These elements can be added to the body to produce a beneficial effect • The warning is that small amount is beneficial, but too much is dangerous and can lead to toxicity

18. Heavy metals/Trace elements • Harmful elements known to have adverse physiological significance at relatively low levels include heavy metals such as - As, Cd, Cr, Pd, Zn and Hg and - also include the radioactive elements such as U,Ra, Rn, Th, Es • All trace elements are toxic if ingested or inhaled at sufficiently high levels for long enough periods of time

19. TOXICITY • Toxicity is the degree at which chemical substances have ability to induce biochemical harmful effects to bio-receptors (living organisms- plants, human, animals) • Three categories of toxicity • Acute toxicity • Accelerated toxicity • Chronic toxicity

20. Acute toxicity -is the effect of toxic when one massive dose of toxic element is taken from a single exposure or from multiple exposure in a short period of time -Mainly occurs at less than 24 hours -But still can be up to 14 days from the days of taking the substances

21. Accelerated toxicity -it is the intermediate stage of toxic effect after single or multiple exposure in an intermediate period of time - Mainly occurs after exposed to acute toxicity when no treatment had encountered

22. Chronic toxicity – effects of exposure to small doses over a long period of time • Progressive effect of toxic elements • Mainly effect becomes permanent and can not be cured

23. Sources of toxic elements • Natural and • Anthropogenic Sources

24. Natural Sources Accumulation of heavy metals due to natural sources is through: • Chemical and physical weathering of rocks • Decomposition of plants, animals detritus • Precipitation • Volcanic activity • Wind erosion • Forest fire smoke • Oceanic spray • Floods • Earth quakes

25. Anthropogenic activities Accumulation of heavy metals due to anthropogenic activities include activities such as: • metalliferous mining and smelting • Agricultural and Horticultural materials • Sewage sludges • Fossils fuel combustion • metallurgical industries, manufacture, use and disposal of metals commodities • electronics • waste deposal • metal, smelting , • corrosion of metals in use, • forestry, • agriculture, • sports and leisure activities.

26. Natural sources: • The movement of chemical compounds among various path through the lithosphere, hydrosphere, Atmosphere and biosphere • These constitute the Geochemical circle

27. Geochemical Circle

28. The most common natural origin of trace elements is the Geochemical origin- chemical constituents from geological environment. • Trace elements occurs as trace constituents of primary minerals in igneous rocks – crystallized magma • They become incorporated into these minerals by isomorphously substitution which is governed by ionic charge, ionic radius and electronegativity of the major elements and trace element .

29. Trace constituent of rock forming minerals: MineralTrace constituentssusceptibility to weathering • Olivine Ni, Co, Mn, Li, Zn, Cu, Mo easily weathered • Hornblende Ni, Co, Mn, Li, V Zn Cu Ga • Biotite Rb, Ba, Ni, Co, Zn, Cu, • Garnet Mn, Cr, Ga moderately stable • Orthoclase Rb, Ba, Sr, Cu, Ga • Muscovite F, Rb, Ba, Sr, Cu, V • Magnetite Zn Co, Ni, Cr, V • Quarts - Very resistant

30. Weathering of rocks will contribute on soils contamination through processes such as hydrolysis, hydration, dissolution, oxidation and reduction, ion exchange and carbonation • The trace element concentrations in sedimentary rocks are depended upon the mineralogy and adsorptive properties of the sedimentary materials.

31. Mean heavy metal contents of major rock types:

32. Bioavailability of toxic elements

33. This explains the FORM in which elements are available for bioreceptors. • The form in which the element might have negative or positive impacts on the environment • The property of a substance that makes its chemical uptake biota

34. This can be defined as Element Speciation • Distribution of an element among defined chemical species in a system • Speciation – species distribution • Chemical species - chemical elements : specific form of an element defined by its isotopic composition • Speciation analysis – analytical activities in analytical chemistry of identifying and or measuring the quantities of one or more individual chemical species in a sample • This can be denoted as oxidation state and or complex molecular structures.

35. Which then influences the bioavailabity of toxic elements OXIDATION STATE examples As As (III) and As (IV) are toxic Cr Cr (III) -- essential Cr (VI) – highly toxic and cancer promoting

36. Cu • Ionic Cu (II)is toxic in aquatic systems • It is the normal oxidation state for soluble aqueous complexes • It is stable at aqueous complexes

37. C(III) Unstable in aqueous solution Cu+ is classified as soft acid and forms complexes with typical soft base metals

38. Fe • Fe (II) – less toxic • Absorption capacity is lower compared to Fe(III) • Only Fe (II) is effective against deficiency • Important for supplementation • But Fe (III) toxic

39. Hg • Inorganic mercury salts are less dangerous than methylated forms • These are more toxic than inorganic mercury

40. Inorganic Compounds & Complexes • These are readily consumed in either liquid or gas, especially water • The distribution of an element among different compounds affects its transport and bioavailability by determining properties as charge, solubility and diffusion coefficient.

41. ;EXAMPLES 1 (Ni) Ni salts of NIcl or Ni(SO4) are water soluble and of low oral toxicity Ni oxides or sulphur are highly insoluble in water, but their bioavailability may be influenced by biological legands. (A legands is a group of ions or molecule coordinated to a central atom or a molecule in a complex) ;Trinickel disulphide (Ni3S2) is an important carcinogen in animals.

42. Exposures are seldom to a single species of Ni. For example, in various refining operations workers may encounter N3S2, NiO, Ni, Ni-Cu oxides, Ni-Fe oxides, NiSO4, Nicl2 and NiCO3 • Inmost natural waters (ph 5-9) the free dominant Ni species are either the free Ni2+, NiCO3, Ni(OH)2, NiSO4, Nicl2 and Ni (HN4)2.

43. Under the reducing conditions the low solubility of Ni sulphide may limit dissolved nickel concouter EXAMPLE 2 (Cu In contrast to Ni, Cu can form stable compounds in more than one oxidation state Cu(ii) is the normal oxidation state for soluble aqueous complexes,

44. Although insoluble complexes of Cu(i) are also stable. • Cu(iii) complexes are relatively few in numbers and are unstable in aqueous media. • Cu(i) is classified as a soft acid and forms complexes with typical soft bases- iotidessulphurthiosulphates etc. It is only stable at vary low equilibrium concentration.

45. Stable insoluble Cu(i) compounds includes CuCN, Cucl, Cu2S. The Cucl and Cu-cyanide are even more stable in water than Cu(ii) complexes • The relative stabilities of Cu(i) and Cu(ii) species in soluble values considerably depending upon the nature of the ligands present

46. EXAMPLE 3 (Zn) • Zn has only one oxidation state, Zn(ii) that is stable. • In terms of its reactions with ligands, it is intermediate between the hard and soft acids • It has greater solubility and generally higher concentrations than most metals. • However the widespread use of Zn makes contamination a real problem

47. Concentrations are generally low for wider drainage; 0.00002-0.0018 mg/liter • But concentration in rivers are relatively high up to 0.0156 mg/liter or more in cases of anthropogenic pollution. For example, giltrale fraction of water drainage • In normal pH range waters; • Free Zn-ion is the predominant form. • Then CO32- and (OH)- are the dominant species

48. EXAMPLE 4 (Pb) • A member of group IV (C, Si, Ce, Sn) • Like Cu and Zn it is intermediate between hard and soft acids. • It has more than one oxidation state. • Background concentration of Pb; 0.000006-0.000050 mg/L, measured in remote streams in the U.S.A.

49. Concentrations of rivers affected by mining are generally up to 0.065-1.11 mg/L • It is the low oxidation state, Pb(ii), which is the most stable under normal oxidisingconditions. • Below pH 7.1; Pb(ii) is present as free ion and for pH >7.1 it exists as a carbonate (PbCO3) and hydroxide

50. Adsorption plays a major role in controlling concentration in solution.