BIOC65 - exam notes (2).docx

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Biological Sciences
Melissa Whitfield Aslund

Study Suggestions and Exam Notes Lecture 1Introduction of Environmental ToxicologyBe able to define Toxicology Environmental Toxicology Ecotoxicology Toxicology is the study of the adverse effects of chemical physical or biological agents on living organisms and the ecosystem including the prevention and amelioration of such adverse effects Environmental Toxicology branch of Toxicology concerned with the study of toxic effects caused by natural or synthetic pollutants to the constituents of ecosystems animal including human vegetable and microbial in an integral contexto Considers the following FOUR reasons Release of contaminants to the environment Fate and transport of contaminants with or without chemical transformation Exposure of one or more target organisms and Response of individual organisms populations or communities Ecotoxicology is the study of the effects of toxic chemicals on biological organisms especially at the population community ecosystem levelo Ecotoxicology is a multidisciplinary field which integrates toxicology and ecologyBe able to describe Paracelcus contribution to toxicology mainly dose makes the poison Father of toxicology was a physicianalchemist Key corollaries 1 Experimentation is essential in the examination or responses to chemicals2 One should make a distinction between the therapeutic and toxic properties of chemicals3 These properties are sometimes but not always indistinguishable except by dose and4 One can ascertain a degree of specificity of chemicals and their healing or toxic effectsAll substances are poisons there is none which is not a poison The right dose differentiates a poison from a remedy This was the first sound articulation of the doseresponseUsed mercury as a drug to treat syphilis What was the impact of Silent Spring silent spring discussed the state of the environment in relation to chemical products pesticides and its relationship with bird deaths cancers and unknown effects indictment of synthetic pesticide misuse and a major trigger for environmental movement in North America We intend to tackle the problems of environment not only in the Northern regions but everywhere in Canada by directing our efforts mainly to the two major sources of pollution urganziation and the invasion of modern technology The present government is firmly determined that no such acts of madness will be allowed to go on indefinitely at least in CanadaIt caused several environmental safety acts to forcibly occurWhat were the toxicants behind the effects in the ecological disasters in Minamata Chernobyl Bhopal What was a common thread behind these disasters poor safety practices Poor understanding and use of excretion of toxic substancesProper care was not taken in regards to such deadly substances o In Minamatathey used mercury as a catalysis for a process did not realize the deadly effects of it The shellfish were contaminated and the locals were eating it o In Chernobylpoor safety and design flaws caused pipes to blow and spread radioactive dust everywhereCaused the risk of cancer to increase o In Bhopaldue to lack of workforce leading to improper safety precautions the leaking in pipes of MIC occurredGas spreadthroughout the city killed twenty thousand and still hundreds of thousands are effectedLecture 2Principles of ToxicologyWhy did the researchers not originally determine the cause of Minamata disease How was the cause ultimately confirmed They began noticing that people around the minamata bay that were eating the fish and the shellfish were getting sick and the cats that were feeding from there shared similar illness symptoms as the people o Led researchers to suspect that there was contaminated fish and shellfish o They tasted the waste water coming from the factory and found several chemicals they didnt test mercury because its expensive to test o Later animal testing showed that mercury was the leading cause of the deatho Mercury went from the waste water into the bay then into the fish and then into the Definitions of Toxin Toxicant Poison Xenobiotic LD50 LC50 LOAEL NOAEL Potency Efficacy Acute Chronic Subchronic Placebo Nocebo Systemic ToxicityToxin Toxic substances that are produced naturallyo eg animal based poisonsToxicants Toxic substances that are produced or are a byproduct of anthropogenic activity o eg dioxinproduced from the combustion of chlorinated organic chemicals o Chemicals with cross over too PAHs Poison Any substance typically at low doses that causes a harmful effect when administered to a living organism Xenobiotic Any chemical interacting within an organism that does not occur in normal metabolic pathways of that organismo ie anthropogenic chemicals Lethal Dose 50 LD50 Refers to the dose needed to produce death in 50 of treated animals eg mgkg bw
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