10884459
Description
Flashcards by Flora Dong, updated more than 1 year ago
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Created by Flora Dong
over 6 years ago
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| Question | Answer |
| What's the difference between a xenobiotic versus anthropogenic? | Xenobiotic = susbstance foreign to the organism Anthropogenic = man-made substances Both may be harmful or useful |
| What's the differencece between a toxin & toxicant? Give examples of each? | Toxin = toxic substance made by living organisms (Ex. mycotoxin) Toxicant = non-biological, man-made (anthropogenic) toxic substance (ex. PAH, PCBs, dioxins) |
| Who's the first toxicologist? What did this person hypothesize? | The first toxicologist is Parceleus (swiss physician). Gave the hypothesis that "the dose makes the poison" (i.e. toxicity isn't just substance dependent but conc. dependent) |
| On the dose response curve, what's on the x- and y-axis, respectively? | X-axis = dose (conc.) Y-axis = % viability |
| What was the focus of Rachel Carson's environmental toxicology movement? | Insecticide DDT |
| List the 4 basic steps of toxicant action | 1. Release into the environment 2. Exposure of toxicant to organism 3. Uptake by the organism 4. Adverse response elicited in organism |
| Name the 5 major classes of environmental contaminants | 1. Inorganics 2. Organics 3. Pesticdes 4. Complex effluents 5. Radioisotopes |
| What was the problem observed in chimney sweeps and the cause of this problem? | Problem = Percival Potts observed rise of scrotal cancer Cause = PAHs from the soot (as a result of incomplete combustion) |
| What was the cause for the "Mad Hatter" disease? | Inhalation of mercury vapours |
| What is the difference between a contaminant and a toxicant? | Contaminant = could have adverse effects but may be needed by the organism Toxicant = only has adverse effects on the organism |
| Name the 5 elements of a toxicity event. | 1. Generation of contaminants 2. Release of contaminants 3. Movement of contaminant to a receptor (organism) 4. Exposure to organisms at sufficient conc. and time 5. Organism response |
| What are the 2 source categories for toxicants? Give 3 examples & the type of each souce (7 total) | Source category: 1) Point source (P) 2) Nonpointsource (NP) Examples: agriculture (NP), industrial discharge (P), storm runoff (NP), aerosol (pesticdes) (NP) combustion (NP) |
| What 3 properties affect the fate of contaminants? | 1. Water solubility 2. Volatility 3. Environmental half-life |
| What's the relationship between toxicant dose and the type of response elicited? | High conc. toxicant = acute response Low conc. toxicant = chronic response (see graph Y-axis dose, X-axis response time) |
| What's the unit for oral exposure? Topical exposure? Respiratory exposure? | Oral = mass/wt organism (mg/kg) Topical (aquatic) = mass/vol. (uM, ug/L) Respiratory = mass/vol. (mg/L) |
| What are the 2 types of bioassays? From this, what 2 factors need to be considered for bioassays? | Bioassays: Lethality and sublethality Factors: Exposure time and dose concentration |
| What are modifying factors? Give the 2 types plus examples. | Modifying factors = traits that can affect/alter toxicity of a chemical to an organism. Types: biotic (age), abiotic (pH, O2) |
| What is included under the class "inorganic pollutants" (4 total)? | Metals, metalloids, non-metallic inorganics, gases |
| Name 2 functions of metals in living organisms. | 1. Enzyme cofactors 2. Cellular electrochemical gradient & balance (osomoregulation, membrane potential, signaling) |
| What's the key difference between Class A vs. B metals? (i.e. what classifies them?) Give examples of each class. | Class A: Oxygen-seeking (Mg, Ca) Class B: Sulfur-/nitrogen-seeking (Cd, Ni, Cu, Fe, Mn, Zn) |
| Why is Class A less toxic than Class B metals? | Class A metal binds to O, which is abundant outside of organism. Inside the organism, there is also more O than S or N, which leads to less harmful, nonspecific binding. Class B metals bind to S/N, which are usually AA side chains, often in enzyme active sites and thus inhibit enzymatic functions. |
| Name 3 anthropogenic sources of metals and 3 other sources of metals. | Anthropogenic sources: Industrial effluent, metal mining, agriculture Other sources: Paints, ash, lumber |
| Name 3 ways of how metals can elicit toxic effects | 1. Binding to enzymes 2. Interfere with essential metal uptake (ex. K or Ca) 3. Formation of reactive oxygen species to oxidize lipid bilayer or damage DNA |
| Why are organometals more hazardous than free metals? Explain with example. | Organometals have organic groups that make them more lipophilic and suppports diffusion into biological membranes. An example of this is methyl mercury. Hg on its own cannot diffuse across membrane (has charge), but methylated form can easily cross lipid bilayer and accumulate in organism. |
| Name and describe 3 environmentally important organometals. | 1. Tributyl tin (TBT) - antifouling compound 2. Tetraethyl lead - anti-knock compound in gasoline to increase efficiency 3. Methyl mercury - methylated by microorganisms; acts as neurotoxin which leads to behavioral and reporductive impairments |
| Name the 2 forms of ammonia - which is more hazardous and why? | Ionized form (NH4+) and non-ionized form (NH3). NH3 is more hazardous because of its ability to diffuse across membrane. |
| Name the point and nonpoint sources of ammonia. | Point source: urban waste via landfills Nonpoint source: farm land via fertilizer |
| What 2 factors affect unionized NH3 conc. and how? | 2 factors: pH and T Increased pH and increased T both increase conc. of ammonia |
| Describe how unionized and ionized form of ammonia affect fish? (2 different mechanisms) | Unionized: Crosses the lipid bilayer via passive diffusion Ionized: uses the active transporter & moved inward as a mimic of K+ because of similar ionic radius (Na/K pump) |
| What are the outcomes of ammonia in fish? (4 in total) | 1. Increased energy demand (since it's exchanged for K+) 2. Intracellular pH disturbance that affect endo & exocytosis 3. Electrochemical disturbance 4. Inhibition of enzymatic reactions |
| What's the difference between Cl2 vs. Cl-? What are their targets? | Cl2 is gaseous, Cl- is ionic. Cl2 is used for water treatment to kill harmful microbes. Cl- has no effect on humans but is toxic to plants. |
| Where is cyanide found and why is it hazardous? | Cyanide is generated via mining & metal processing. It inhibits oxidative phosphorylation (i.e. anything that has an electron transport chain) |
| What characterizes an isotope? (Relative to the actual element) | An isotope has different number of neutrons compared to original element |
| What's the difference between isotopes and radioisotopes? | Radioisotopes are unstable and spontaneously decays. |
| Name all types of ionizing radiation. | X-ray, gamma ray, alpha particles, beta particles |
| Difference between what's measured by radioactivity vs. radiation dose? | Radioactivity measures the conc. of the radiation. Radiation dose measures the energy deposited in biological tissue (i.e. how much radiation was received) |
| Chernobyl accident releases 2x10^18 Bq radiation. Express this in curie and in DPM. | 5.4 x 10^13 curie 1.2 x 10^20 DPM |
| Poland expsoure to Chernobyl accident radiation was 1.2 mSv. How many rem is this? | 1Sv = 100 rem 0.12 rem |
| Name the functions of UVA vs. UVB. | UVA is essential for DNA repair. UVB damages DNA |
| How does UV radiation cause damage? | UV radiation result in photosensitization damage by product of ROS and damaging DNA (thymine dimers) |
| What makes up petroleum hydrocarbons (PHCs) | Aliphatic and aromatic hydrocarbons of C5-C50 length |
| Describe the toxicity of low MW vs. high MW PHC toxicity? | Low MW = volatile, more bioavailable, more toxic, but most are consumed High MW = adsorb onto sediments, reduced bioavailability, but more persistent |
| Name the PAHs with 2 fused rings, 3 fused rings (2), 4 fused rings (2) | 2 rings: naphthalene 3 rings: anthracenene and phenanthrene 4 rings: pyrene, chrysene |
| How is PAH produced (natural and anthropogenically?) | PAH is mostly produced from combustion or incineration. Naturally: produced by volcanoes & forest fires. Anthropogenically: produced by gasoline combustion, metal refining, tobacco smoke, car exhaust |
| What are the main environmental sinks for PAHs? | Soil, sediment |
| What is the source of PCB? | Only anthropogenic origin. From insulating fluids of electrical equipments ad hydraulic fluids. |
| What are the biological consequences of PCB? | PCB is highly persistent (due to presence of Cl not degraded by biological systems). Interferes with endocrine system of vertebrates. |
| Where do dioxins and furans come from? | Mainly arise form production of PCB (ex. bleaching) |
| What makes dioxins and furans so toxic to biological systems? | Not easily metabolized or excreted and lead to high bioconcentration. Thus highly carcinogenic. |
| What do PAH, PCB, dioxins and furans have in common that make them carcinogenic? | All of these are planar, highly lipophilic molecules that partition into membrane and intercalate into DNA. Mistakes during repair = carcinogenic. |
| Name the traits of an ideal pesticide | 1. Kills quickly 2. Persists only long enough to kill and breaks down to non-hazarouds compounds 3. Only kills target organisms and cheap to manufacture |
| What is the target and mode of action for DDT? Why is it banned in North America? | Target = insects MOA = penetrates waxy cuticle of insect exoskeleton & disrupt nerve function (via Na+ balance) Banned because has adverse effect on fish-eating birds. |
| What is common about all insecticides? | They are all neurotoxins |
| What are the 2 modes of action for herbicides? Give example that uses each mode. | 1. Disruption of photosynthesis, broad-spectrum herbicide (ex. methyl viologen or atrazine) 2. Mimics auxin, plant growth hormone and disrupt growth, dicots (ex. phenoxyherbicides) |
| What is glyphosate and why is it a better alternative to other herbicide? | Glyphosate = organophosphate that targets a plant enz. Adv.= microbial degradation (i.e. not persistent); not toxic to mammals |
| What is the major concern of pharmaceutical products? | Uncontrolled release into the environment (pharmaceuticals are biologically active) |
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