Intro/Assessment of exposure Flashcards
what is toxicology?
The study of the adverse effects of xenobiotics on biological and ecological
systems
what is a xenobiotic?
any substance that is foreign to a biological system
what is a toxicant?
a chemical produced by humans, after introduction into the environment produces harmful effects
what is a toxin?
a harmful substance produced within a cell or an organism
what are the similarities of toxicology and pharmacology?
- actions of molecules
- require understanding of physiology, anatomy, chemistry, molecular biology
- Pharmacodynamics/pharmacokinetics
- Dose matters
- Patient-specific effects
what are the differences between toxicology and pharmacology?
- Undesired vs. desired effects
- Actions of poisons / toxins that would not be used as therapeutic agents
- Effects of chemicals on the environment
- Number of molecules ++ in toxicology
- Physical exposure is important in toxicology (e.g., sound)
what phrase/idea did Paracelsus coin?
concept of the dose response relationship (the dose makes the poison)
what is a toxicon?
is a chemical entity and not a mixture
what is a hazard?
something that has a potential of harming you
what is a risk?
- the likelihood of a hazard causing harm
- risk = Hazard x exposure
What parameters make up total exposure?
Exposure = intensity (how much) x frequency (how often) x duration (how long)
what is the exposure pathway?
The route a substance takes from its source (where it began) to its endpoint (where it ends), and how people can come into contact with (or be exposed to)
what are the 5 parts of the exposure pathway?
- A source of exposure
- An environmental media and transport mechanism
- A point of exposure
- A route of exposure
- A receptor population
what are the levels/types of exposure data from best to worst?
- Quantitative personal dosimeter measurements
- Quantitative ambient measurements in vicinity of residence or activity
- Quantitative surrogates of exposure, e.g., estimates of drinking water
- Residence or employment in proximity of source of exposure
- Residence or employment in general geographic area, e.g., county, of source of exposure
What challenges might we face in “measuring” exposure (i.e. obtaining exposure data)?
- factors influencing biodistribution (for measuring living beings)
- some activity patterns might be different
- mixtures
- homogeneous vs heterogeneous
what are the steps to get the data?
- sample
- measure
- evaluate
How long should you sample? what does it depend on?
Minimum time needed to obtain sufficient amount for lab analysis
- Sensitivity of analytical procedure
- Dependent on contaminant concentration
when sampling air, what are we testing for?
Pollutants:
- from fuel combustion
- industrial processes
- solid waste disposal
- Explosions and fires
- pesticide drift
Particulate – in an aerosol or suspension
Lungs trap particles of what size?
0.5-5.0 μm in size
How do you sample air? which method is better for volatile and non-volatile compounds?
Sampling: by directing air through a filter (not good for volatile
matter) or through an absorbent (to capture gases)
what is PM2.5?
Fine Particulate Matter 2.5 µm in size or less
How do you sample soil? How do you choose which method?
Depends on properties of pollutants
- Surface sampling strategy
- Vertical distribution – coring devices (To determine the depth of contamination and cleaning needed)
what are the Principles of sampling soil?
A soil test is only as good as the sample
- Collect separate samples according to: soil type, slope, crop, history,
fertilizer, etc..
- Collect 20-25 sub-samples
- Sample on a grid system
what are the different grid systems to sample soil?
- simple random
- stratified random
- systematic
