3. Assessment of Exposure Flashcards
What is risk?
Risk is the likelihood of a hazard causing harm
Exposure is necessary for there to be a risk.
Hazard x exposure = risk
What is hazard?
Something that has the potential to harm you.
What are the relationships between:
- Exposure and risk
- Hazard/toxicity and risk
The more you are exposed the higher the risk
The more hazardous the more likelihood for risk
What parameters make up total exposure?
Exposure = how much x how often x how long
= intensity x frequency x duration
What is an exposure pathway?
The route a substance takes from its source (where it began) to its endpoint, and how people can come into contact
What is beneficial about knowing the exposure pathway?
Some exposures have a super simple route and some have really long ones. Knowing the pathway tells us how we can control exposure to a person directly or even limiting output of something into the pathway.
What are the 5 parts of an exposure pathway? How are they defined?
- A source of exposure, such as using a consumer product for a household task or a chemical spilled from a truck onto a highway. (where the toxicant originated from, not the toxicant itself)
- An environmental media and transport mechanism, such as movement through the indoor or outdoor air or groundwater.
- A point of exposure, such as a person’s house or a private well.
- A route of exposure: eating, drinking, breathing, or touching. Not to be confused with exposure pathway.
- A receptor population: a person or group of people potentially or actually exposed.
Ingestion and inhalation are examples of which part of the exposure pathway? A. Exposure transport B. Exposure media C. Exposure route D. Point of exposure E. Exposure population
C. Exposure route
What are the different methods of collecting data?
- Quantitative personal dosimeter measurements
- Ex: Measure of how much radioactivity each person is exposed to by wearing a dosimeter. - Quantitative ambient measurements in vicinity of residence or activity
- Measurement of the toxicity in the general area. Ex: CO measure in your house - Quantitative surrogates of exposure, e.g., estimates of drinking water
- Ex: We measured the amount of lead in ur water and estimated how much water you have drunk in the past couple of days to estimate how much lead you were exposed to - Residence or employment in proximity of source of exposure
- Residence or employment in general geographic area, e.g., county, of source of exposure
- General approximation. Ex: air, water, and soil in general geographic area
At what point in the exposure pathway is each method of collecting data taken at?
- Quantitative personal dosimeter measurements
- Receptor Population - Quantitative ambient measurements in vicinity of residence or activity
- Point of exposure - Quantitative surrogates of exposure, e.g., estimates of drinking water
- Transport/point - Residence or employment in proximity of source of exposure
- Source - Residence or employment in general geographic area, e.g., county, of source of exposure
- Source
What is the most accurate type of exposure data?
- Quantitative personal dosimeter measurements. The other levels are still useful but we have to take them with a grain of salt because there is variability and error that we have to be aware of.
What is the least accurate type of exposure data?
- Residence or employment in general geographic area, e.g., county, of source of exposure
Which exposure data would be the best approximation to an actual exposure level?
A. Analysis of shellfish indicated there is approximately 20 μg domoic acid (toxin) per gram of shellfish in the USA
B. Water in your private well shows a reading of 1.3 ppm of copper
C. Ground water in Dresden, Ontario showed 39 out of 54 analyses on its raw water supply contained up to 6.4 μg/L of the pesticide atrazine
D. California is the least healthy state in terms of air pollution, at a value of 12.8 (of particulate matter)
B. Water in your private well shows a reading of 1.3 ppm of copper
What challenges might we face in measuring exposure?
Factors influencing biodistribution
-> Different levels of toxicity in different species
Homogeneous vs heterogeneous
- > its easy to test water bc its homogenous
- > Soil and food is heterogeneous and its harder to measure
Time activity patterns
-> over time you may not be exposed to the same amount
Mixtures
-> its difficult to say that one specific substance is toxic on its own and doesn’t have interference with other molecules (ex: synergy)
What are the steps of Identification and quantification of chemicals in the environment and living beings?
- Sample
- Measure
- Evaluate Data
What are the steps of getting a sample?
- Defining the question: why and what to sample
2. Develop a sampling scheme: how, where, and when
What are the questions needed to develop a sampling scheme?
How long to sample?
- Minimum time needed to obtain sufficient amount for lab analysis: Sensitivity of analytical procedure, Dependent on contaminant concentration
Whom to sample?
How many samples to collect?
How should the samples be obtained?
What are the different areas you can sample from?
Air, soil, water, food, and tissues
What are we testing for when sampling air? Why?
Pollutants from fuel combustion, industrial processes, solid waste disposal, explosions, fires, pesticide drift
Particulate matter in an aerosol or suspension
- Lungs trap particles 0.5-5 um in size
Particles enter through the nose and mouth (nose and throat irritation). Larger particles (ex: particulate matter <=10 microns) are eliminated through coughing, sneezing, and swallowing. Smaller particles (ex: PM <= 2.5) can travel deep into the lungs causing heart and lung problems.
How do you sample air?
By an air sampling device: by directing air through a filter (not good for volatile matter…better for larger particles) or through an absorbent (to capture gases). To trap particles, concentrate it, and eventually measure it.
