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Lecture 2

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Department
Biology
Course
BIOL 354
Professor
Bruce Greenberg
Semester
Summer

Description
BIOL354 – Environmental Toxicology I Spring 2012 Lecture 2: Contaminants from Source to Receptor to Impact - Contaminant Fate studies: Investigates the origins, concentrations, partitioning & persistence. o E.g. Total [SSRI] with increasing distances (Highest @ point of release, dilutes as it travels, & accumulates meters downstream) (Searching for [] that induce side effects) - Contaminant Effect studies: Evaluates biotic & abiotic consequences of contaminant exposures. o E.g. Mating behavior & egg production of Japanese medaka (Already @ the [] for negative effects to occur, monitors different effects compare to a normal control group). - Contaminant movement: o Environment: Abiotic simple diffusion o Organisms: Biotic bio-concentrated (water uptake) or bio-accumulated (water & food uptake). (Higher [] in the organism relative to the environment)  Food chain: Bio-magnification in higher organisms (especially PCBs & dioxins).  Accumulates more in adipose tissues than muscle tissues.  Lipophilic drugs do not accumulate (except for synthetic estrogen, which can bind to a variety of receptors) - Toxicity Event: Generate contaminants, release, & transport them into a biotic receptor (protein, tissue, or organism) through up-take. Biotic receptor is exposed @ a sufficient [contaminant] & duration, resulting in an adverse biological response. - Toxicants enters the environment from 2 sources: o Direct point source discharges: Sewage water discharge, & industrial super-stack. The bigger source, easier to measure & regulate. o Indirect non-point source discharges: Agricultural & urban runoff, automobile exhaust & UNTREATED discharges down the road drainages (extremely toxic). The smaller source, much harder to regulate & [contaminant] cannot be measured. - Exposure Routes: o Oral: Dosage of toxicants administered to the organism through the mouth or diet.  Dose: weight of toxicant/weight of organism (1 ppm = 1 mg Kg ).  Rotovap (lab): Uniformly dose food for oral administration. o Injection: Dose administrated directly into the bloodstream through intravenous, subcutaneous, or intra-peritoneal methods (skips the digestive tract). o Topical/Surface: Toxicants applied on to the skin (e.g. dermal antibiotics etc. in patches).  Amphibians are highly sensitive to environmental toxicants. o Respiratory: Inhalation of certain concentration of toxic air via lungs or gills.  Left lung bigger than right lung, higher rate of lung disease @ right lung (less SA).  Concentration: weight of toxicant/volume of air or water (1 ppm = 1 mg L ). - Bioassay: Determine toxicant effects (if the chemical is toxic & how toxic it is relative to others). o Sufficient exposure time at a given range of doses/concentrations. o Sufficient doses/concentrations within a given period of exposure. - Toxicity responses (@ molecular, biochemical, individual, species or community levels) o Based on degree of response:  Lethal: Response is death (results reveal less information).  Sub-lethal: Response/changes other than death (3 organizational levels).  Individual changes o Biochemical: Enzyme inhibition; o Hormonal: Cortisol level changes u
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