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Toxicology_notes

Toxicology_notes - Biology 232 Toxicology 1 Toxicology =...

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Biology 232 Toxicology 1 Toxicology = Study of adverse affects of substances on human health o How the body processes and reacts to poisons Toxins - derived naturally from plants and animals (e.g. ricin, strychnine, aflatoxin) Toxicants resulting from human activities (Arsenic, DDT, Hg, PCBs, etc). Toxicologists determine relative toxicity of compounds LD 50 = dose at which 50% test animals die within specified time frame Anything can be toxic – depends upon dose (Exhibit 2.1, p 52-53) Depends on frequency, intensity and duration of exposure TOXICOKINETICS = Absorption, distribution, metabolism, excretion Absorption: routes = Inhalation, ingestion, dermal contact Human envelope = boundary separating interior of body from exterior environment Dose = a quantification of exposure (mg/liter, ug/m 3 , concentration) Biologically effective dose = quantity available to interact with vulnerable tissue Distribution – toxicant distributed through body via bloodstream, lymph system via diffusion Metabolism - chemically transformed by enzymes into metabolites Cytochrome P450 - polymorphism in genes coding for P450 leads to different metabolic phenotypes Water soluble chemicals excreted more quickly Lipophilic substances stored in fat cells; Lead stored in bone Methylmercury (hydrophobic) crosses blood-brain barrier to beome neurotoxin; Inorganic mercury
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