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Lecture 3

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BIOL 354
Bruce Greenberg

BIOL354 – Environmental Toxicology I Spring 2012 Lecture 3: Inorganic Pollutants - Dose vs. Concentration o Dose: Total amount of substance administered/taken/absorbed by organism.  Amount of solute if given in an aqueous form. o Concentration: Quantity of substance per unit of a give medium/system (solute per solvent).  Actual amount inside the organism is UNKNOWN. - Modification Factors: Factors that can change the toxicity of a toxicant. o Biotic: Species, sex, age (Plastic: Bisphanol A w/ estrogen, great effect on developing boys), size, & nutrition. o Abiotic: Exposure routes, partitioning (Organic Carbon as hydrophobic sediments), pH,2O (Oxidization), hardness, temperature, & light. - Inorganic Pollutants (Metals, metalloids, non-metallic inorganics & inorganic gases) o Metals: (NATURALLY OCCURING @ low [], majority are ANTHROPOGENIC)  Natural sources: Weathering of metal-bearing rocks.  Anthropogenic sources:  Disposal/leaching from landfills.  Sewage sludge run-off when used as an inexpensive nutrient amendment.  Metal-based pesticides with arsenic & mercury (impacts CNS).  Ash & cinder disposal from burning firewood, incineration & cremation.  Lead pellets (Gizzards -> Lead poisoning); Pressure treated wood (Playground w/ arsenic, chromium & copper); Tanning Leather, & “tawing” of pigs/goats (arsenic & chromium).  NOT BIODEGRADABLE, are lustrous, malleable, & good electrical conductors.  Can be an essential micronutrient or non-essential/toxic substance.  Metal speciation: form(s) of an element in a given sample. o Free metal ions, inorganic metal complexes, simple organic metal complexes (EDTA) & metal complexes w/ biotic organic matters (Fulvic/humic acids). o Metals shift between species depending on factors like environmental pH, etc.  Bioavailability & toxicity can be affected by chemical speciation. o Metal chelators: detoxifies by forming complexes with free metal ions.  Non-Essential metals: Cadmium: Batteries & paints; Chromium: Stainless steels; Lead: Extensively in gasoline, paints & batteries, toxic; Mercury [NOT HIGHLY TOXIC]: dental amalgams, gold, fungicides, thermometers, electrical tilt switches [Methylated mercury is EXTREMELY TOXIC].  Essential metals: Copper/Zinc/Iron, incorporated into macromolecules (large & organic) as chelates or as enzyme co-factors (ATP, ADP, etc.) or they can exist as free ions.  Chelates: Hemoglobin (Fe ), hemocyanin (Cu ), & chlorophyll (Mg ). o Limit+ reactivity/enhance+ affinity by trapping Oxyge2+molecules.  Free Ions: Na (osmoregulation), K (membrane potential) & Ca (various functions). o High [KCl] injection: lethal & untraceable. o Metalloids:  Non-metallic elements but with some similar properties to metals.  They are less lustrous & are semi-conductors (electronics).  Arsenic: in pesticides, wood preservatives, mine tailings, & playhouses, TOXIC. o Non-metallic inorganics (Ammonia):  Ammonia (Un-ionized) NH [D3NGEROUS]  Ammonium cation (Ionized) NH 4 + +  Tests usually checks BOTH [NH 3 NH ]4  Sources of release:  Point sources: [significant] municipal wastewater effluent discharges, high [30mg/L], can kill a rainbow trout in less than 2 hours. BIOL354 – Environmental Toxicology I Spring 2012  Non-point sources: [trivial] landfills, fertilizers, household cleaners, pulp & paper, steel mills, & [significant] farm manure.  Ammonia Toxicit
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