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Lecture 9

EESA10 - Lecture 9 notes.doc

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University of Toronto Scarborough
Environmental Science
Michael Petit

Toxicology – Lec 09 Toxicology - chem. Contaminants and hazards, bad risk assessments done on all hazards like physical, cultural, etc Toxicology: Assessing chem. (1) - chemical partitioned b/w: - water, soil, air, our bodies - dissociation: anions diff than cations - water soluble : organic chemicals, heavy metals, - Fat soluble: DDT, most organic chem. Accumulate in fat (are fat soluble) - Depends on chem.. characteristics of sub - Some found more in soil/air Toxicology: Assessing chem. (2) Persistence -> some chemicals cant break down Biomagnification: Increase of conc of chem. In organisms in food chain Bioaccumulation: accumulation of some toxicant in organ of an ind. Ex. Liver Multiple chemicals-> hard to detect only 1 chem…usually exposed to mixture of chemicals Antagons: in presence of carcinogen it can reduce effect ex. Vit A/ E in presence of conc Synergestic: can reduce can affect If 2 chemicals found together that effect will be even worse ex. Asbestos ->carcinogen-> and if person is smoker and exposed to asbestos chances of getting lung cancer is even greater Receptor: Who? Dose: Amount of chem. Response: rxn/ symptoms Toxicology: receptor - Receptor: someone receiving dose/ chemical - Organism -> human - Frequency-> how freq and how long dose time - Age-> infants and elders - Gen health-> is there any chronic illnesses / has poor health can suffer more - Gen makeup-> parents transfer things to us and some are more naturally resistant they are worst case scenarios Toxicology: Dose - inhaled thru lungs - skin contact (dermal contact is mostly industrial chemicals ) Toxicology: Response - Nonspecific- no specific tissue in body that will be affected - Conc of acids or bases -> destruction of cells - Specific -> know certain organ tissue that will be hurt by toxin - Acute toxicity-> dramatic symptoms - Chronic toxicity-> lasts for long time with mild symptoms and Hard to cure - Some chemicals we know where the level of exists (level of exposure exists) - Ex Calcium .. too many pills can cause harmful effect - Ex. Water drink 3L at once you can be poisoned (not chemically) but it will be too much for the stomach - Ex. 100 coffees the level of caffeine in the body will cause death - Ex.100 tablets of aspirin or Tylenol Measuring Manifestations - Endpoint: when someone uptakes chemical before any sign of symptoms : its hard to measure; don’t know what to measure - Measurement Endpoint: sym. We can recognize -> body is reacting - use of biomarkers shows changes in hormone levels due to exposure Method for determining toxicity - LD is detected by Lethal Dose 50 - LD 50 ->es that group of animals receive as a single does that will casue mortality of 50% of individuals during period of 14days - Case reports come from physicians -> from data, suicide attempts; accidental poisoning - Dose- Response: increase of dose what happens to response - Primates and humans not allowed Dose- Response Curves: - can
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