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Lec 9, Previous was Lec 8

Environmental Science
Course Code
Jovan Stefanovic

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Toxicology: assessing chemical hazards (2)
Chemical interations
oAntagonist- reducing toxicity- affect of getting disease is lower
oSynergeistic- albestine- directly related to lung cancer
Multiple chemicals make it more difficult to measure toxicity
oEx) food additives, pesticides, and air pollution
When looking at the toxicity we look at three things
o1. RECEPTOR- living organism receiving dose
Imp to know how many times they are exposed ( frequency of measure)
Age- children and adults are more vulnerable
Genetic makeup- genes that make you non resistant
General health- esp for elders
o2. DOSE- amount person receives through different roots
Ingestion most common 85%
Absorption- 5%
Acute dose: nuclear power plant accidents for example
Chronic dose- repeated dose- radiation
Long term- first day of life to entire life
Low dose and is constant
o3. Reponse adverse human health effects can be specific or non specific
Specific- we can distinguish which particular organ is affected
Non specific the whole body is affected

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Mutagenesis- gene affected
Carcinogens- multiplication of cells
oChronic toxicity lasts many years before you die
Dose makes the chemical toxic
3 litters of water at once causes death; 100 cups of coffee causes death
Every chemical is toxic at the same dose, different for each person
Difficult to measure if mixed
Measuring manifestation
oEndpoint: first moment when we can measure something that will tell us
something is wrong iwth our body
Ex) hormones, enzyme production imbalance
These are biomarkers: things we can measure
Determining toxicity on animals
oFirst thing needs to be measure is the lethal dose
oCauses mortality of 50% of animals in 14 days
Methods for determining toxicity
Beside experiments wtih animals case reports can be done by physicans
Epidemiological studies: control group and ones professionally exposed: these two
groups must match in gender age etc.
oAnd the researchers find statistical significance between the two
When data is collected, the response curve is drawn ( dose response curve): always
accumulated toxicity ( one dose)
oDose response curve
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