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46 Cards in this Set
- Front
- Back
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Xenobiotic |
foreign substance to an organism - may produce useful or harmful/toxic results |
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Anthropogenic |
Man - made substances - do not naturally occur |
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Toxin |
toxic substance made by living organism |
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Toxicant |
Man-made toxic substance (anthropogenic), or substance with non-biological origin Ex. metals, PAHs, PCBs |
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First Toxicologist |
Paracelsus PARA- CELSUS |
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Paracelsus Saying about Toxicity |
Everything is toxic; nothing is toxic. It is the dose that makes the poison |
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First Env Toxicologist |
Rachel Carson Silent Spring Book - DDT |
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No Exposure = No Effect Toxicant must go through 4 steps to have an effect on an organism - RETR |
1. RELEASED & MIGRATE in env 2. EXPOSED to target organism 3. TAKEN UP/ ABSORBED/ UPTAKE by target organism 4. RESPONSE in target organism (causes) RETR |
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Classes of Environment Contaminants |
Inorganic - Metals. CO2, NaCl Radiation and Radioisotopes Organic = PAHs, Dioxins, Furans Pesticides= DDT, organophosphates Complex Effluents = STP, Steel, Paper Mills |
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Pollution / Contaminants |
Substance in environment that causes adverse effects ** contaminants not always Toxicants eg. Phosphorous - eutrophication, overgrowth of algae, takes up all oxygen and fish die |
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Paradigm Shift From what to what |
Dilution Paradigm - solution to pollution is dilution Boomerang Paradigm - what you throw out can come back to harm you |
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Contaminant Entry into Env: Point Source Discharge |
Toxicant comes from direct source - Industrial waste, sewage discharge |
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Contaminant Entry into Env: Non-point Source Discharge |
Toxicant come from indirect source - car exhaust, urban run off |
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Give 5 examples of Contaminant Sources in Environment |
1) Accidental Release - Nuclear Accident 2) Deliberate Application - pesticides & Fertilizers 3) Disposal for/ or Release of Waste - STP 4) Combustion or Incineration - auto exhaust 5) Land & Groundwater Entry - landfills leach contaminants into environements |
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Fate of Contaminants: Fate depends on what kind of Properties? |
VOLATILITY: vapor pressure, VOCs -> move in air WATER SOLUBILITY: organics - low solubility so usually partition into sediments and org membranes inorganics - some soluble, affects bioavailability HALF-LIFE: Highly variable based on chemical |
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Exposure Routes For Contaminant 4 Main Routes |
1) ORAL 2) INJECTION 3) TOPICAL OR SURFACE 4) RESPIRATORY |
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ORAL ROUTE Described and dosage measurements |
Entry of toxicant through mouth or diet - org can be dosed with specific amount Units for dose = weight toxicant/ weight org 1pp (parts per M) = 1mg/Kg 1ppb = 1ug/KG |
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INJECTION ROUTE |
exposure through intravenous, subcutaneous, intraperitoneal (body cavity- perineum) |
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TOPICAL/ SURFACE ROUTE |
Applied to or taken up dermally - exposure to toxicant based on concentration units: uM, ug/ml, ppm |
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RESPIRATORY ROUTE |
Exposure from: air - inhalation , water - gills exposed to specific concentration Units: Weight toxicant/ Volume water 1ppm = 1mg/L 1ppb = 1ug/L |
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What is used to determine effects of toxicant on an organism/ group? |
Bioassay |
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Lethality Bioassay |
Determines is contaminant causes death & how toxic it is relative to other contaminants |
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Important Part of a BIOASSAY |
0) Test Organism (implied) 1) Exposure Time - time for response to occur at a specific toxicant dose or concentration 3) Dose/ Concentration - amount of toxicant required to develop a response in given period |
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Bioassay Modifying factors Biotic Abiotic |
Adjust toxicity of chemical to an organism BIOTIC: species, sex , age, size, nutrition ABIOTIC: exposure route, pH, partitioning, temp |
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INORGANIC POLLUTANTS Includes 4 Groups |
1) Metals: Cu 2) Metalloids: As 3) Non-metal Inorganics: Ammonia (NH3), NaCl 4) Inorganic Gasses: CO2, NH3 |
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List Most Toxic Metals |
Hg, Pb, Cd ** -- heavy metals very bad Cu, Fe, Ag, Al, Zn, Ni, Cr, Cd, Au Ag, Al, Au, Cd, Cr,Cu, Fe, Hg, Ni, Pb, Zn |
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Metal Characteristics |
Elements - NOT BIODEGRADABLE Good electrical conductors Bioavailability and toxicity affected by speciation Metals can be REQUIRED, TOXIC or Both - Ca required, Hg toxic |
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Metalloids - Define them - Characteristics |
Elements with properties between metals and non-metals - semi conductors - less lustrous eg. Se, As |
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Metals & Metalloids of Concern |
Al, As, Cu, Ca, Ch, Pb, Hg, Ni, Se, Ag, Sn, Zn |
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Metal Functions in Organism What metals are required in an organism (3) Why? |
Essential metals in macromolecules Required: Fe, Cu, Zn incorporated into macromolecules ie Enzyme cofactors: Hemoglobin (Fe) Chlorophyll (Mg) Mitochondrial function (Ca) |
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Important Metal Ions For Biota Function |
Na+: Osmoregulation K+: membrane potential, neurons Ca: muscle contractions |
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Two Classes of Metals CLASS A |
- OXYGEN SEEKING ex. Ca, Al, Mg - Complex w/ O>N>S - Associate with func groups: carboxyls carbonyls alcohols phosphates - found on left and bottom of periodic table |
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CLASS A Target Molecules |
Phospholipids - cell membranes Nucleic Acids- RNA, DNA ATP & ADP |
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CLASS B Metals |
SULFUR OR NITROGEN SEEKING ex. Cu, Fe, Ni, Pb, Zn, Mn, Cd - complex with S>N>>O Associate with func groups: Sulp-hydryls Disulphides Thioethers Amines |
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CLASS B Metals Target Molecules |
Amino Acids Proteins Free Nucleotides |
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Metal Occurence - How are they occuring - What has greatly increased metal levels in the environment |
Naturally occurring ANTHROPOGENIC ACTIVITY - metal mines, smelting Increased metal level in environment makes metals more bioavailable - alters distribution and availability - weathering of metal bearing rocks & soil |
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Sources of Metal Contamination Ubiquitous throughout environment, where found naturally |
Found through environment, usually in low concentrations - soil, sediment , surface water - weathering of metal-bearing rocks and soil releases metals into env |
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Sources of Metal Contamination Anthropogenic Sources |
1) Industry - metal mining, oil mining 2) Urban Waste - leaching of metals from garbage, industrial fills, solid wastes 3) Agriculture - metal based pesticides (Hg, As) 4) Other Sources - Ash/cinders when burnt - Paints (Pb, Sn) - Tannery (treat skin with Cu, Cd) |
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Metal Toxicity Toxic Effects: think what it does to things in the cell, structure and what can be produced |
Bind to molecules, alter function: - enzyme binding and blocking of active site Uptake interference of essential metals - block receptors so no uptake Generation of Reactive Oxygen Species (ROS) - oxidizes bilayer (less membrane fluidity) - DNA damage |
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Are organometals more or less hazardous than free metals? |
MORE HAZARDOUS |
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3 Environmentally Important Organometals |
1) Tributyl Tin - used as anti-fouling compound, found in boat paints 2) Tetraethyl Lead - found in gasoline but now phased out - organometallic Pb more bioconcentration and enhanced toxicity over ionic Pb 3) Methyl Mercury - in env from biomethylation from biotransformation - no imp bio function |
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NON METAL INORGANCS; Two Forms of Ammonia |
1) Unionized NH3 2) Ionized NH4 Total Ammonia - NH3 + NH4 |
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Ammonia Sources |
Landfills, Sewage, Household Cleaners |
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Toxicity of Ammonia Caused by Amount in env depends on (2) |
UNIONIZED NH3 Depends on 1) ph - increase pH = increased amount of NH3 2) Temp - increase temp = increased NH3 |
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Ammonia Toxicity in Fish - causes what kind of disorder - disturbs what processes |
Causes NEUROLOGICAL DISORDER - disturbs the electrochemical gradient - proton gradient specifically - Inhibits exo and endocytosis - NH4 competes with K for inward transport - fish require more energy |
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Other Inorganics Name 2 |
Chlorine (Cl2) - highly reactive and toxic - used to treat water Cyanide (CN-) - Inhibits OXIDATIVE PHOSPHORYLATION - stops ATP prod in mitochondria |
