Lecture 6 Flashcards
Any condition which provides an opportunity for an external environment agent to contact (and enter) the human body:
Exposure
Measure or estimate of the intensity, frequency, and duration of human exposure to an agent:
Exposure assessment
Characterize relationship between varying exposures and incidences of adverse effects in exposed populations (environmental epid):
Dose-response assessment
T or F: mere presence of a contaminant at some concentration does not necessarily imply that people will be exposed
T
Concentration _______ exposure _____ dose
is NOT, is NOT
Exposure = _________ x __________ x __________
magnitude x frequency x duration
T or F: personal measurements are always the best
T
ADME is a fundamental notion in pharmacology and toxicology and stands for
Absorption
Distribution
Metabolism
Excretion
net accumulation of a contaminant in an organism from a) all external sources, including air, water, and solid phases (ex: food, soil, sediment) and b) all internal processes:
bioaccumulation
net accumulation of a contaminant in organism from water only
bioconcentration
What are the 3 key components of bioaccumulation:
1) uptake
2) biotransform
3) eliminate
Bird exposure to an oil spill:
- Bird is exposed to the oil on his feathers
- Absorption through skin, bird is going to try cleaning his feathers
- Ingestion of contaminated food, gets broken down in the intestine and gets absorbed in the gut / goes to bloodstream
- Breathing / inhalation - can be exposed through his lungs
Biologically mediated transformation of a chemical compound to another:
Biotransformation
Biotransformation leads to ____________________ and involves __________________
increased elimination, de-tox and toxification, sequestration, redistribution
enzymes limited by saturation kinetics
T or F: dimethylmercury is very toxic
T
Give some examples of biotransformation of metals:
1) organic conversion by microbes
2) sequestration by methallothioneins (30% cysteine, binds 6-7 metal atoms/protein)
3) biomineralization (Pb incorporation into bone, Hg-Se crystals)
T or F: organics are rapidly excreted or metabolized
T
What are the goals with the phase 1 transformation of organics:
- Make them more H2O soluble
- add COOH, OH, NH2, SH (hydrophilicity)
- oxidation reactions (hydrolysis, reduction)
What are the goals with the phase 2 transformation or organics:
- to make the phase 1 products conjugated (adding a tag to get rid of it - sends a message to the body that we want to get rid of it
- add cysteine, glutathione, glycine, glucorinic acid (promote biliary elimination)
T or F: the intermediates can often be more dangerous compared to the original molecule
T
Excretion is a _________ process, biotransformation is a ___________ process
physical
chemical
Contaminated organism placed in clean environment; loss of contaminant monitored over time =
Depuration
Different types of excretion (physical process):
1) Liver (hepatic clearance) = large MW compounds (more than 300 da) - liver (biotransform) / bile (solubilize lipids) / feces; mainly organics
2) Kidney (renal clearance) = lower MW (less than 300 da); passive - active filtration; mainly metals
__________ are naturally occurring isotopes
Stable isotopes (same atomic number, different atomic mass)
15-N stable isotopes as __________
tracers
As you move up the food chain, the body will take more of the ___________ nitrogen
heavier (shows biomagnification of mercury)
N15 levels are going up when herring gulls are eating more _________
smelts
Gulls are eating at a ____________ position
lower trophic
Do we have a high magnification effect on terrestrial food chains?
No (only first-level predator)
