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Environmental Science
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Jovan Stefanovic

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Lecture 5 Metals and Human HealthHeavy Metals3Define Based on atomic weight based on density all elements having density higher than 7gmcm Trace elements are elements found in a lower concentration Very low sometimes hard to detect Naturally occurring extracted from the earth ground in ore in different forms Used for different applicationsWide environmental dispersion water food air etcTendency to accumulate in select tissuesToxic in even low concentrationsClassification of metals1 Class AK Na Mg Ca AlMacronutrients essential for biologicalphysiological processesUsually cations Tend to form ionic bond Opposite forces are attracted to each other Na can react with Clform table salt Low electro negativity tendency to lose rather than acquire electrons Low toxicity2 Class B Hg Ti Pb Ag Au Nonessential elements not needed by the body and can interfere in the body Tend to form covalent bond High electro negativity tendency to acquire rather than lose electrons Very toxic form soluble organometallics3 Borderline Cr Cu As Co Ni Zn Mn FeContribute in many important physiological processes MicronutrientsToxicityClass BBorderlineClass AMechanism of toxicity1 Blocking essential functional groups such as proteins or enzymes proteins cant carry anything2 Displace other metals class B borderline3 Modifying the active conformation of biomolecules twisting of molecules class B like what you see in the mirror Really harmful for humans Coping Mechanisms Resistancespecies develop mechanisms not to uptake metal example Pb Tolerancethe capacity of species to withstand high level of metals There are two types of chemicals threshold and nonthreshold chemicalsInternal detoxifying mechanisms Binding to nonsensitive compound structures not very toxic
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