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
when sampling water, what do you have to consider?
- Pollutants from agriculture, industry (municipal wastes or spills)
- Up and downstream effects
- Speed of flow of water
what are the strategies for Sampling water?
- Surface water – grab technique
- Continuous monitoring
- Entrapment procedures (to concentrate particles, organic pollutants)
in food, Toxic agents can be acquired during what?
- Production
- Harvesting
- Processing
- Packaging
- Transportation
- Storage
- Cooking
- Serving
How can we measure exposure based on food?
- Dietary survey of individual consumers
- Per capita consumption rates – e.g, (production + import) /
population - Direct sample analysis
what is Tolerable daily intake (TDI)?
estimated quantity of contaminant that we can be exposed over a lifetime without posing a significant health risk
When do we sample tissues?
- Forensic/medical studies
– Body fluids: saliva, blood, urine, semen
– Body tissues: liver, kidney
– Hair - Experimental studies (i.e. to study Metabolism; Toxicokinetics; Toxicodynamics)
- Environmental studies (plants and animals)
NIDA (National Institute of Drug Abuse; USA) performs tests for 5 groups of
which drugs?
- Cocaine
- Opiates
- Cannabinoides
- PCP (1-(1-phenylcyclohexyl)piperidine)
- Amphetamines
how long do the following stay in urine:
Marijuana, Opiates, Cocaine metabolites, LSD
- Marijuana:3-30 days
- Opiates: 2 days
- Cocaine metabolites: 2-4 days
- LSD: undetectable
How do you actually get the data from a sample? (the steps to measuring)
a. Extraction
b. Separation
c. Identification
How do you extract a sample (extraction process)?
make the sample homogeneous (typically liquid phase)
-physical (crush, blend etc)
-chemical (extracting with solvent)
what is the purpose of chromatography?
concentration & purification of samples
what is the principle of chromatography?
compounds interact differently with different phases
- stationary (solid/liquid) phase
- mobile (liquid/gas) phase
So unique properties of compound will determine its solubility, affinity, retention time
what does a stationary phase contain in chromatography and what are the different types?
silica + functional groups
- Reverse phase: hydrocarbon chains (bind to hydrophobic compounds)
- Anion Exchange: ammonium groups (bind negative compounds)
- Cation Exchange: carboxyl groups
What do we need to consider when choosing a method to identify/quantify a sample?
- sensitivity
- throughput (how fast and efficient)
- specificity
- identification vs quantification
what are the different Identification/quantification methods?
- Spectroscopic methods (UV/Vis/IR spectra)
- Colorimetric/optical (not quantitative)
- mass spectra
what do you need to consider when evaluating data?
- Compare sample to controls (positive and negative) and standards
- Statistical significance
what are you trying to see when evaluating data?
Relevance and risk assessment
