Introduction to Geo-medicine - Yola

Introduction to Geo-medicine - Yola

Introduction to Geo-medicine 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 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


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 Pearsons correlation Use of remote sensing and GIS in human health studies Analytical techniques in environmental Geochemistry

Geochemical Data bases Projects Berylliosis Group A Talcosis Group B Siderosis Group C Geophagia Group D

Podoconiosis and Kaposiss sarcoma Group E 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

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.

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. 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.

Why Why this this new new discipline? 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. 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 multidisciplinary 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 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.

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 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 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. 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 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 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 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 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

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 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 Sources of toxic elements Natural and Anthropogenic Sources 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 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. Natural sources: The movement of chemical compounds among various path through the lithosphere, hydrosphere, Atmosphere and biosphere These constitute the Geochemical circle Geochemical Circle 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 . Trace constituent of rock forming minerals :

Mineral Trace constituents susceptibility 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 Orthoclase Rb, Ba, Sr, Cu, Ga Muscovite F, Rb, Ba, Sr, Cu, V Magnetite Zn Co, Ni, Cr, V

Quarts - Very resistant moderately stable 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. Mean Mean heavy

heavy metal metal contents contents of of major major rock rock types: types: Bioavailability of toxic elements 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 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. 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 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 C(III) Unstable in aqueous solution Cu+ is classified as soft acid and forms complexes with typical soft base metals

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 Hg

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

;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.

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. 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, 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- iotides sulphur thiosulphates etc. It is only stable at

vary low equilibrium concentration. 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 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 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 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; 0.0000060.000050 mg/L, measured in remote streams in the U.S.A. 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 oxidising conditions.

Below pH 7.1; Pb(ii) is present as free ion and for pH >7.1 it exists as a carbonate (PbCO3) and hydroxide Adsorption plays a major role in controlling concentration in solution. Organic Complexes Organometallic Compounds Organometallic compounds are compounds containing a covalent bond between a carbon atom and a metal. Toxicity often results from bioaccumulation of

fatty tissues and penetrations of membrane barriers EXAMPLE Ionic Hg(ii) is toxic to the mammalian kidney and corrosive at sides of mucosal absorptions CH3Hg+ Crosses the blood-brain barrier, acting as teratogen (any substance that interferes with the normal embryonic development) and central nervous system toxin. Metals that undergo biomethylation-Hg, Ce & Sn

Biomethylation of metals is generally restricted to microorganisms in sediments and soils with the exception of Co in Vitamin B12 Note; Methylation of metals generally increases their toxicity, Methylation of As & Se contributes to their detoxification Manufactured organometallic also find their way into the environment through deliberate addition to treat seed grains eg (Phenyl) Sn as a fungicide and CH3As(ONa)2 as a herbicides

or as (CH3)4 Pb and (C2H5)4 Pb during gasoline. In the environment, binding to polyamons such as humic and solic acids and to colloidal particles contributes to the patterns of transport or availability of elements e.g. Cd ,Cn & Pb Pathways of toxic elements is soils animals and plants

For identification of environmental impact, conceptual model of pollution can be used as a flow chart in order to follow the chain in determination of the pathways of toxic materials to bioreceptors Conceptual model Elements emitted from sources are dispersed in the environment (air, in water and soils) through several transport agents

Wind transportation- metal rich dust and particulates Rainwater and flood flows into rivers and lakes Gravity movement of particles down the sides of heaps into rivers or onto soil Land , air or seaanthropogenic transportation Placement direct tipping of material During transportation, some heavy metals are deposited in soils that are taken by biota and some are absorbed by humans and follows the route of chemical absorption

Key routs of chemical absorption, distribution and Excretion ABSORPTION Mouth, Lungs skin Inhalation Dermal contact

GI Tract Ingestion DISTRIBUTION Blood and Lymph System EXCRETION Feces, Urine, Expired Air, secretion RETENTION

Soft tissue, bones, Fat Absorption, where toxic materials might be ingested through the mouth, or inhaled through the lungs or through dermal contact with the skin Distribution, this where these toxic chemicals will be distributed through the blood and the lymph system Excretion, toxic materials will then be excreted as feces, urine, expired air Retention, when the toxic materials are not excreted then they are retained in the body such as in soft tissue, bones or

as fat In plants absorption of heavy metals are taken up by roots system from soil solution, which can be by: Passive (non-metabolic) uptake, involving diffusion of ions in the soil solution into the root endodermis Active (metabolic) uptake which takes place against the concentration gradient but requires metabolic energy and can therefore be inhibited by toxins

Relative difference in the uptake of the ions is due to several factors such as surface area of the root, rate of evapotranspiration and roots exudates General order of transfer coefficient for most of biologically controlled heavy metals were deduced as indicated in tabled below, which is the metal concentration in plant tissue above ground divided by total metal concentration in the soil Soil-plants transfer coefficients of heavy metals

Element Soil-Plant Transfer coefficient (SPTC) As 0.01 0.1 Cr 0.01 -0,1

Cu 0.1 10 Pb 0.01 0.1 Zn 1 10

Dose Response Curve Dose-response curve is a simple X-Y graph relating the magnitude of a stressor (e.g. concentration of a pollutant, amount of a drug, temperature, intensity of radiation) to the response of the receptor (e.g. organism under study) - The response may be a physiological or biochemical response, or even death (mortality)

The measured dose (milligram, micrograms, or grams per kilogram of body-weight) is generally plotted on the X axis and the response is plotted on the Y axis the curve is typically sigmoidal , with the steepest portion in the middle It usually illustrate the dose of the essential elements Simply relates the exposure dose and the measurable biological effect It should be realised that dose-response

relationships will generally depend on the exposure time; quantifying the response after a different exposure time leads to a different relationship and possibly different conclusions on the effects of the stressor under consideration. 90 natural occurring elements 73 are trace elements in the body 18 of 73 are essential trace elements Abundance by mass % of major and minor

elements in the human body Element Mass% element Mass% Oxygen 65

Calcium 1.4 Carbon 18 Phosphorus 1 Hydrogen

10 Magnesium 0.50 Nitrogen 3 Potasium

0.34 Sulfur 0.26 Sodium 0.14 Chlorine

0.14 Abundance of some trace elements in the human body element Arsenic Bromine Cobalt Chromium Copper Fluoride

Iron Iodine lithium Mass% 0.26 2.9 0.021 0.094 1 37 60

0.19 0.009 element Manganese Molybdenum Nickel Selenium Silicon Tin Tungsten Vanadium

Zinc Mass% 0.17 0.08 0.14 0.11 260 0.24 0.008 0.11 33

If an essential trace element is completely withdrawn from the diet , signs and symptoms of deficiency should occur , such as growth retardation and loss of hair supplementation should alleviate the symptoms and reverse the deficiency state Changing nature of diseases Toxicity

This can be explained by toxicity Toxicity/Poisoning - chemical injury to body organs or a chemically induced disturbance of the functions in biological systems Such toxic effects may follow the exposure to exogenous (environmental) substances Substances that normally are considered as harmless may also, if the dose is big enough, cause deleterious effects and thereby act as poisons Examples of this are sodium chloride, oxygen and water.

The science devoted to the study of the structures, effects and fate of poisonous substances is called toxicology Clinical toxicology deals with problems related to poisonings in humans and their treatment Poisoning may be acute, accelerated or chronic Acute Toxicity In acute poisoning the body is exposed to the toxic substance in a high dose, on one occasion and during a short period of time

Symptoms of poisoning develop in close relation to the exposure Examples of acute poisonings are massive drug overdoses, poisonings after mushroom meals, alcohol poisonings, and bites or stings Acute poisoning just means 1 big dose of a poison that kills something or someone all at once

So, death by lethal injection is acute poisoning The circumstances around an acute poisoning are often obvious and easy to detect Mainly occurs at less than 24hours But still can be up to 14 days from the days of taking the substances Chronic Toxicity In chronic poisoning the organism is on the contrary exposed repeatedly to toxic agents during a long period, but every exposure means that just a low dose of the poison is entering the body

Normally no symptoms develop in relation to each exposure, although that may happen (e.g. in chronic exposure to solvents) Instead the patient gradually becomes ill after a period of months or years In chronic poisoning the toxic substance may accumulate in body tissues or cause a small irreversible damage at each exposure After a long time, enough poison has been accumulated in the body, or the damage has become significant enough, to cause clinical symptoms

Examples of typical chronic poisonings are long-term exposure to heavy metals like lead, mercury or cadmium, inhalation of organic solvents in the occupational context, and exposure to pesticides. chronic poisoning is a buildup of toxic chemicals over time the slow and insidious onset of a chronic poisoning may cause considerable diagnostic difficulties. Accelerated toxicity

Is intermediate between chronic and acute toxicity Develops after 5 -10 years of heavy exposure to toxic elements It is the late stage of acute toxicity and early stage of chronic effect Symptoms of chronic diseases starts to show off. Sources , pathways and effects of excess/deficiency of :

Selenium, lead, mercury, zinc, and cadmium Selenium Selenium is a non metallic chemical element. In chemical activity and physical properties it resembles sulfur and tellurium Selenium appears in a number of allotropic forms: the most popular are a red amorphous powder, a red crystalline material, and a gray crystalline metal like form called metallic

selenium. Se Selenium burns in air and is unaffected by water, but dissolves in concentrated nitric acid and alkalis Low levels of selenium can end up in soils or water through weathering of rocks It will then be taken up by plants or end up in air when it is adsorbed on fine dust particles. Selenium is most likely to enter the air through coal and oil combustion, as selenium dioxide.

Se This substance will be converted into selenium acid in water or sweat Selenium substances in air are usually broken down to selenium and water fairly quickly, so that they are not dangerous to the health of organisms Selenium can accumulate in the body tissues of organisms and can then be passed up through the food chain Se Usually this bio magnification of selenium starts

when animals eat a lot of plants that have been absorbing large amounts of selenium, prior to digestion Due to irrigation run-off concentrations of selenium tend to be very high in aquatic organisms in many areas When animals absorb or accumulate extremely high concentrations of selenium it can cause reproductive failure and birth defects Se - Selenium exposure takes place either through food or water,

or when we come in contact with soil or air that contains high concentrations of selenium. -This is not very surprising, because selenium occurs naturally in the environment extensively and it is very widespread. -The exposure to selenium mainly takes place through food, because selenium is naturally present in grains, cereals and meat. - Selenium uptake through food may be higher than usual in many cases, because in the past many selenium-rich fertilizers have been applied on farmland. Se

People that live near hazardous waste-sites will experience a higher exposure through soil and air Selenium from hazardous waste-sites and from farmland will end up in groundwater or surface water through irrigation This phenomenon causes selenium to end up in local drinking water, so that exposure to selenium through water will be temporarily increased. Se People that work in metal industries, selenium-recovery industries and paint industries also tend to experience a

higher selenium exposure, mainly through breathing Selenium is released to air through coal combustion People that eat a lot of grains that grow near industrial sites may experience a higher exposure to selenium through food Exposure to selenium through drinking water may be increased when selenium from hazardous waste disposals ends up in water wells. Se Exposure to selenium through air can cause dizziness, fatigue and irritations of the mucous membranes

When the exposure is extremely high, collection of fluid in the lungs and bronchitis may occur. Selenium uptake through food is usually high enough to meet human needs; shortages rarely occur. When shortages occur people may experience heart and muscle problems. When selenium uptake is too high health effects will be likely to come about. Se The seriousness of these effects depends upon the concentrations of selenium in the food and how often this food is eaten.

The health effects of various forms of selenium can vary from brittle hair and deformed nails, to rashes, heat, swelling of the skin and severe pains When selenium ends up in the eyes people experience burning, irritation and tearing. Selenium poisoning may become so severe in some cases that it can even cause death. Se Overexposure of selenium fumes may produce accumulation of fluid in the lungs, garlic breath, bronchitis, pneumonitis, bronchial asthma, nausea,

fever, headache, sore throat, shortness of breath, conjunctivitis, vomiting, abdominal pain, diarrhea and enlarged liver Selenium is an eye and upper respiratory irritant and a sensitizer. Overexposure may result in red staining of the nails, teeth and hair Se Selenium deficiency causes rare endemic diseases where there is low level of Se in soil Keshan cardiomyopathy and Kashin Beck diseases, which are deforming arthritis (China)

Mild deficiency of Se causes heart and cancer (Europe) Lead -Lead is a soft, malleable poor metal, also considered to be one of the heavy metals -Pb is mainly light blue in colour which is soft and resistance to corrosion -It was mainly used in petrol (gasoline), but is being phased out on environmental grounds -Used in manufacturing car battries, electrodes, in the glass of computer and television screens, bullets,

Pb Native lead is rare to find in nature, but naturally is found in zinc, silver and copper ores and it is extracted together with these metals Metallic lead does occur in nature, but it is rare. Lead is usually found in ore with zinc, silver and (most abundantly) copper, and is extracted together with these metals. The main lead mineral is galena (PbS), which

contains 86.6% lead. Pb Other common varieties are cerussite (PbCO3) and anglesite (PbSO4). Besides occurring naturally more concentrations found in the environment are a result of anthropogenic activities Example is Pb from petrol - Chlorines bromines and oxides pollute the environment- through the exhausts of cars Larger particles pollute soils or surface waters, the

smaller particles will travel long distances through air and remain in the atmosphere Pb Its main pathways are through uptake of food, (70%), water (20%) and air (10%). Example of Foods staff include fruit, vegetables, meats, grains, seafood, soft drinks and wine may contain significant amounts of lead Cigarette smoke also contains small amounts of lead Lead can enter (drinking) water through corrosion of pipes especially when water is highly acidic

Pb Effects of Pb include: Brain damage, Miscarriages, anaemia, blood pressure, Kidney damage, Infertility of men, Lowering IQ of children, hyperactivity and damage to the nervous system and the brains of unborn children. Other anthropogenic activities include not fuel combustion, industrial processes and solid waste combustion Lead can end up in water and soils through corrosion of leaded pipelines in a water transporting system

and through corrosion of leaded paints. Pb It cannot be broken down; it can only converted to other forms. Lead accumulates in the bodies of water organisms and soil organisms. --Fish can take place even when only very small concentrations of lead are present. Body functions of phytoplankton (O) can be disturbed when lead interferes. -Soil functions are disturbed by lead intervention, especially near highways and farmlands, where extreme concentrations

may be present. Mercury (Hg)

It is heavy , silver metal Liquid at room temp. but solidifies at - 40C Boils at 355 C High specific gravity 13.6 Alloy with other metals Part finder of cinnabar Main ore of Hg Rhombohedral crystal structure t can be extracted by heating cinnibar in a current of air

Hg It occurs in two oxidation state Hg (I) and Hg (II) It exists in the form of inorganic and organic mercury Methylation of inorganic mercury into organic mercury occurs in the microorganisms under anaerobic conditions e.g in underwater sediments Organic mercury is highly poisonous and it is easily absorbed by the gastric and intestinal organs It is then carried by blood into the brain , liver and kidney Natural sources Hg

Extremely rare native element on Earth crust Also found in cinnibar and also in other minerals such as corderite and livingstonite Mercury ore generally occurs in belts where rocks of high density are forced to the crust of the earth Often in hot spring or other volcanic regions Natural source such as volcanic eruption is responsible of almost half of the atmospheric Hg emissions Release in the environment anthropogenic sources

The rest of % is mainly released by human generated activities which include: Emission of stationary coal combustion and oil combustion Gold production Cement production Waste disposal- municipal and hazardous waste and sewage sluge From steel production Mercury production for batteries Applications

Cosmetics manufacturing of mascara Production of chlorine and caustic soda Cl is produced from NaCl using electrolytes to separate Na from Cl Caustic soda is produced by dissolving salt in water and brine is produced with byproduct being NaOH Dentistry main ingredients in dental amalgams Hg in Gold mining For century Hg has been used for

amalgamation of gold It is estimated that about 1.32 kg of Hg is lost for every 1 kg of Au produced About 40% of this loss occur during the initial concentration and amalgamation stage of Au The lost is released directly into the soil, streams and rivers, initially as inorganic Hg, which later converts into organic Hg Hg in Gold mining This is taken into the food chain, mainly by fish and other aquatic life

The remaining 60% Hg is released directly into the air when the Hg is released directly into the air when Hg Au amalgam is heated during the purification process and is often inhaled Hg is a very volatile element, thus dangerous levels are readily obtained in air Safety standards require that Hg vapour should not exceed 0.1 mg/m3 in air Hg in Gold mining Hg once taken in, is accumulated into the human body and attacks the central nervous system, resulting in:

numbness and unsteadiness in the legs and hands, awkward movements, tiredness, ringing in the ears, narrowing of the field of vision, los of hearing, slurred speech, loss of sense of smell and taste and forgetness Hg in Gold mining Hg poisoning may lead to disease known as minamata

Minamata disease was first detected in 1956 in Minamata Bay Japan It was caused by eating large quantities of fish or shell fish contaminated by industrial discharges of Hg compounds in Minamata Basin 200mg/L of Hg in blood and 50mg/g in hair are the provisionally established standards and any higher concentration is considered to be at risk of poisoning The allowable level of methyl Hg in fish is 0.3ppm Zinc Zinc, is a bluish-white, lustrous metal. It is less dense than iron

and has a hexagonal crystal structure. The metal is hard and brittle at most temperatures. Zinc is a fair conductor of electricity. It has relatively low melting (420 C) and boiling points (900 C). Metals long known to form binary alloys with zinc are Aluminium, antimony, bismuth, gold, iron, lead, mercury, silver, tin, magnesium, cobalt, nickel, tellurium and sodium. Zinc makes up about 75 ppm (0.007%) of the Earth crust, making it the 24th most abundant element there. Zn

Soil contains an average of 64 ppm, but actual soils have 5770 ppm zinc. Seawater has only 30 ppb zinc and the atmosphere contains 0.1 to 4 g/m3. The element is normally found in association with other base metals such as copper and lead in ores. Zinc is a chalcophile ("sulfur loving"), meaning the element has a low affinity for oxygen and prefers to bond with sulfur in highly insoluble sulfides. Zn Other minerals from which zinc is extracted include

smithsonite (zinc carbonate), hemimorphite (zinc silicate), wurtzite (zinc sulfide), and sometimes hydrozincite (basic zinc carbonate). With the exception of wurtzite, all these other minerals were formed as a result of weathering processes. Exploitable reserves of zinc exceed 100 million tonnes, with large deposits in Australia, Canada and the United States. Zinc deficiency occurs where insufficient zinc is available for metabolic needs. Zn It is usually nutritional, but can be associated with

malabsorption, acrodermatitis enterropathica, chronic liver disease, chronic renal disease, diabetes, malignancy, and other chronic illnesses. Diets rich in foods that contain a lot of phytic acid, such as cereals and legumes, decrease zinc absorption into the body. Zinc supplements are important and help prevent disease and reduce mortality, especially among children with low-birth weight or stunted growth. Zn Symptoms of chronic zinc deficiency are stunted

growth and retarded sexual development. Plants that grow in soils that are zinc-deficient are more susceptible to disease. Even though zinc is an essential requirement for a healthy body, excess zinc can be harmful. Excessive absorption of zinc suppresses copper and iron absorption. Zn The free zinc ion in solution is highly toxic to plants, invertebrates, and even vertebrate fish. Stomach acid with HCl, will cause metallic zinc to

dissolves readily to give corrosive zinc chloride. Levels of zinc in excess of 500 ppm in soil interferes with the ability of plants to absorb other essential metals, such as iron and manganese. -Chronic ingestion of over 1 kg of zinc results in death due to gastrointestinal bacterial and fungal infections. Zn Ingestion of about 12 grams of zinc, only shows lethargy and ataxia (gross lack of coordination of muscle movements) Pennies and other small coins are sometimes ingested by

dogs, resulting in the need for medical treatment to remove the foreign body. The zinc content of some coins can also cause zinc toxicity, which is commonly fatal in dogs, where it causes a severe anemia, also liver or kidney damage; vomiting and diarrhea are possible symptoms. Storing fruit juices in galvanized cans has resulted in mass poisonings of zinc Cd Cd is a Lustrous, silver white , ductile, very malleable metal

Its surface has a bluish tinge and the metal is soft enough to be cut with a knife, but it tarnishes in air It is soluble in acids but not in alkalis It is similar in many respects to zinc but it forms more complex compounds Cd in the environment Natural Sources Cd can mainly be found in the earths crust It always occurs in combination with zinc Naturally a very large amount of cadmium is

released into the environment, about 25 000 tons a year About half of this cadmium is released into the air through forest fires and volcanoes The rest of the cadmium is released through human activities, such as manufacturing Natural Sources Mostly Cd ore is not mined for the metal, because more than enough is produced as a byprolduct of the smelting of zinc from its ore, sphelarite (ZnS), in which CdS is a significant impurity, making up as much as 3%

Thus the main mining areas are those associated with zinc World production is around 14.000 tons pre year, the main producing country is Canada, with the USA, Australia, Mexico, Japan and Peru also being the major suppliers Anthropogenic Cd also available in the industries as an inevitable by-product of zinc, lead, and copper extraction After being applied it enters the environment

mainly through the ground and pesticides Also produced during metalliferous mining and smelting Pathways Cd waste streams from the industries mainly end up in soils The causes of these waste streams are for instance zinc production, phosphate ore implication and bio industrial manure Cd waste stream may also enter the air through (household) waste combustion and burning of fossils fuels Because of regulations only little cadmium now enters the

water through disposal of waste water from households or industries Another important source of cadmium emission is the production of artificial phosphate fertilizers Pathways Part of the Cd ends up in the soil after the fertilizers is applied on farmland and the restg of the cadmium ends up in surface waters when waste from fertilizers productions is dumped by production companies Cd can be transported over great distances when it is absorbed by sludge. This Cd rich sludge can pollute surface

water as well as soils When Cd is present in soils it can be extremely dangerous, as the uptake through food will increase Soils that are acidified enhance the Cd uptake by plants This is a potential danger to the animals that are dependent upon the plants for survival Pathways Animal eating or drinking cadmium sometimes get high blood pressure, liver diseased and nerve or brain damage The susceptibility to Cd can vary greatly

between aquatic organisms Salt water organisms are known to be more resistant to Cd poisoning than fresh water organisms Pathways Cd can accumulate in their bodies, especially when they eat multiple plants Cows may have large amounts of Cd in their kidneys due to this earthworms and other essential soil organisms are extremely susceptive to Cd poisoning They can die at very low concentrations and this has consequences for

he soil structure When Cd concentrations in soils are high they can influence soil processes of microorganisms and threat the whole soil ecosystem In aquatuic ecosystem Cd can bio accumulate in muscles, shrimps, lobsters and fish Salt water organisms are known to be resistant to Cd poisoning than fresh water organisms Health effect of Cd Human uptake of Cd takes place mainly through food chain Foodstuffs that are rich in Cd can greatly increased the Cd concentration in human bodies

Examples are liver, mushroom, shellfish, and dried seaweed An exposure significantly higher Cd levels occurs when people smoke Tobacco smoke transport Cd into the lungs Blood will transport it through the rest of the body where it can increase effects by potential Cd that is already present from Cd-rich food Health Effects of Cd This may even cause death Cd is firstg transported to the liver thropugh the blood It is then bounded to proteins to form complexes that

are transported to the kidneys Cd accumulates in kidneys, where it damages filtering mechanisms This causes the excretion of essential proteins and sugar from the body and further kidney damage It takes a very long time before cadmium that has accumulates in kidneys is excreted from a human body Health effects of Cd Other exposures can occur with people who live near harzadeous waste sites or factories that releases Cd into the air and people that

work in the metal refinery industry When people breathe in cadmium it can severely damage the lungs Health effects of Cd

Other health effects that can be caused by Cd are Diarrhea, stomach pains and severe vomiting Bone fracture Reproductive failure and possibly even infertility Damage to the central nevours system Damage to the immune system Psychological disorders Possibly DNA damage or cancer development

Dust emission in mining and mineral processing and the fate of inhaled particles Silicosis Asbestosis Coal workers pneumoconiosis Silicosis Silica is like asbestos, can result in the development of fibrotic lundg disese and results into a disease known as Silicosis Natural Sources: Rock , sand and soil

The most common of crystaline silica is known as quarts Inhailation of air born dust, that contain crystalline silica can occur in a wide variety of settings: - mining, quarrying and stone cutting, founry operations, paintblasting and sand blasting, glass manufacturing and etching and some types construction workings Three types of Silicosis Chronic, acute and accelerated silicosis Chronic silicosis A progressive lung disease, characterized by the development of fibrotic tissue in response of inhalation of quarts particles in the size of

0.5 0.7 micrometer Heart and respiratory failure is the consequences of these type of silicosis Acute silicosis In workers exposed to exceptionally high concentrations of fine particles of silica, usually quarts dust The lungs are often heavy and rigid as the air spaces are filled a finely granular substances Accelerated silicosis

Is intermediate between chronic and acute silicosis Develops after 5 -10 years of heavy exposure to silica dust grater than 1.0 micrometer of almost pure quarts They show no clinical abnormalities other than breathlessness Death by cardiopulmonary failure within ten years of onset of symptoms is often the outcome of this form of silicosis Asbestos Asbestos is the name of a group of highly fibrous

minerals Separable, long and thin fibers Fibers are strong enough and flexible enough to be woven Asbestos fibers are heat resistant, making them useful for may industrial purposes Because of their durability, asbestos fibers that get into lung tissue will remain for long periods of time Types of Asbestos Amphibolite fibers stay in lthe lungs longer than chrysolite this tendency may account

for their increased toxicity Example; Brittle crystalline fibers amphibole minerals (actinolite, tremolite, anthophylite, crocidolite and amosite asbestos) Chryssolite less toxic , e.g. serpentine mineral with long and flexible fibers Exposure to Asbestos We are all exposed to low levels of asbestos in the air Much more concentrated levels of exposure are known to cause health effects in humans

Anthropogenic exposure Anthropogenic exposures asbestos product manufacturing (insulation, roofing, building materials) Automotive rep air (breaks and clutches) Minig operations Railroads Sand or abrasive manufactures Shipyards/ships/ Steel mills

Amphibole exposure Mining activities: Exposure to tremolite asbestos can occur in workers involved in mining . Milling, and handling of other ores and rocks containing tremolite asbestos (such as vermuculite or talc) Residence who live near milling, milling or manufacturing sites Amphibole Asbestos exposure Insulation and building materials amphibole

asbestos can be found in a variety of building materials such as insulation, ceiling boards, , floor tiles and cement pipes Occurs in some vermuciulite sources used as home and building insilation Amphibole asbestos exposure Consumer Products Vermuculite was also commonly sold in gardening and hardware stores It was used as to improve soil quality or fertilizers carrier Small amounts of amphibole asbestos have been

found in some talc containing crayons Manufactures of these crayons agreed to eliminate talc from their products Health effects Significant exposure to any type of asbestos will increase the risk of lung cancer, mesothelioma and nonmaligmant lung and pleural dissorders, This include asbestosis, pleural plaques, pleural thickening, and pleural effusions (5 to 1,200 fiberyear/mL) Such exposure will result from 40 years of occupational exposure to air concentrations of 0.125 to 30 fiber/mL

diseases from asbestos exposure takes a long time to develop Most cases of lung cancer or asbestosis in asbestos workers occur 15 or more years after initial exposure to asbestos Health Effects Tobacco smokers are at far greater risk-than non-smokers who has been exposed to asbestos Diagnosis of mesothelioma from exposure to asbestos commonly has been 30 years or more

Asbestos Facts When asbestos fibers are inhaled, most fibers are expelled, but some can be lodged in the lungs and remain there throughout life. Fibers can accumulate and cause scaring and inflamation Inhaling longer, more durable asbestos fibers ( such as tremolite and other amphiboles) contributes to the severity of asbestos-related disorders Exposure to asbestos, including tremolite, camincrease the likelihood of lung cancer, mesothelioma, ond nonmalignant lung conditions such as asbestosis

Fluorosis Acid Mine Drainage Fluorosis A form of enamel hypomineralization leading to discoloration due to excessive ingestion of fluoride during the development of the teeth It is caused by over exposure to fluorides from all sources ; Fluoridated water, Fluoride toothpaste, Mouth rinses, tablets, gels, sealants, Foodstuffs: tea, medicines, anaetsthetic, pesticides, ,

herbicides, polluted air/dust/fumes This condition can manifest in the form of skeletal fluorosis and dental fluorosis The damage caused by fluorosis is permanent Prevention is crucial Asbestos Facts Changes in the lining of the lungs (pleural) such as thickening , plaques, calcification, and fluid around the lungs (pleural effusion) may be early signs of asbestos exposure These changes can affect breathing

Pleural effusion can be an early warning sign for mesothelioma (cancer of the lining of the lungs) Asbestos Facts Most cases of asbestos or lung cancer in workers occurred 15 years or more after the person was first exposed to asbestos Most cases of mesothelioma are diagnosed 30 years or more after the first exposure to asbestos Mesothelioma has been diagnosed in asbesos workers family members, and residents who live close to asbestos mines Health effects from asbestos exposure may continue to

progress even after exposure is stopped Smoking or cigarette smoke, together with exposure to asbestos, greatly increases the likelihood of lung cancer Dental Fluorosis It is sometimes called enamel fluorosis It starts with small marks and sports on teeth

Mild transparency of the tooth enamel If allowed to progress the teeth will become pitted, cracked and brittle Dental fluorosis usually appears before skeletal fluorosis Skeletal fluorosis Fluoride attacks the bones of the body It causes brittle bones and joint pain Tricky to identify as other diseases may cause the same symptoms In regions where it is endemic it is easily

detected Some tomes x-ray might be done to visualize the bones Importance of fluoride It is an important dietary Effective in cavity prevention The fact that fluorosis exists , is not a reason to stop using fluoride in dental care But just to be careful Fluoride filters can be used to reduce the content of fluoride in fluoridated water

Acid mine drainage Geological aspects of waste disposal including radioactive waste Uranium Geogenic sources of uranium

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