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Lecture 9

Lecture 9 Study Guide

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Environmental Science
Jovan Stefanovic

**not sure about highlights** Lecture #9: Toxicology rd Wednesday, March 23 2011 Toxicology Study of poisonsscience of poisons the science which studies toxic substances or poisons, that are substances which cause alteration or perturbation in the function of organisms leading to harmful effects (Truhaut, 1974) What does toxicology look at? 1. Chemistry of poisons 2. Distributions of poisons that deniesdrives its behaviour 3. How much is it toxic to humansanimals 4. Compare and rank different substances based on toxicity 5. The dose of the substance that makes the substance toxic Assessing Chemical Hazards How harmful substance depends on the following chemical properties of the substance: o Electronegativity o Polarity directly affects solubility of substances Polar substances are soluble in H2O they are found in ECM but not allowed in cell; mostly inorganic substances Polar (fet. sol.) are organic enter the cell and accumulate within cell o Oxidation state (e.g. Cr-6 is more toxic than Cr-3) o Molecular weight o Dissociation what anions and cations are produced o Solubility Water soluble toxins Fat soluble toxin Toxicology depends on: o Persistence of chemical (POP e.g. DDT good as pesticide but not good for overall health o Bioaccumulation o Biomagnification building level in the food chain o Chemical interaction (bw chemicals) Antagonistic ones toxicity is higher than the other Synergistic combined toxicity is higher; e.g. asbestos and smoking increase the risk of cancer total toxicity = higher than each individual toxicity o Multiple Chemicals food additives, pesticides, air pollution Difficult to assess toxicity and difficult to do risk assessment 1. Receptor = the organism receiving exposure or dose Frequency of exposure e.g. everyday, once a month, Age infant, children = vulnerable; elderly = sensitive General health (of receptor @ the time) Genetic makeup genes and alleles 2. Dose = the amount of substance the person has: Ingested (often the greatest source of chemical exposure, 85%) most common route of exposure Inhaled through air pollution, particles and volatiles, 10%
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