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Lecture 9

EESA10H3 Lecture Notes - Lecture 9: Worst-Case Scenario Series, Chronic Toxicity, Median Lethal Dose

Environmental Science
Course Code
Jovan Stefanovic

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Toxicology – Lec 09
- 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
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
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