Final Flashcards
Define risk.
The combination of the predicted or expected probability that an adverse event will occur and the severity or magnitude of the consequences if that event should occur.
List five (5) combinations of factors that may impact the public’s perception of risk.
- Involuntary vs. Voluntary
- Exotic vs. Familiar
- Uncontrollable vs. Controllable
- Caused by humans vs. Natural
- Permanent effect vs. Temporary effect
Explain the trade-off between economic realities and acceptable risk
There are many benefits from industrial activities and people are willing to accept some risks in order to obtain the benefits provided by those activities at a cost that they can afford.
______________________ is a term used to describe a process that attempts to compare environmental risks of various types in order to rank them in importance.
Comparative risk assessment
_______________________ is the term used for the process that attempts to estimate and where possible, quantify, risk posed to the environment and its non-human inhabitants by a given condition.
Ecological risk assessment
Explain the issue that has been raised about comparative risk assessment
A significant problem with comparative risk assessment is in comparing and ranking risks of different types such as cancer, non-cancer health effects, ecological effects and welfare effects
List the benefits of risk assessment
- Identifies risks that can be easily reduced but which would be unknown without risk assessment
- Can be used to clarify what is known and what is unknown
- Provides scientifically defensible risk information for decision making
- Provides basic information for risk communication
List the limitations of risk assessment
- Often extremely complex and difficult to understand
- Many embedded assumptions and uncertainties
- Only as good as our ability to model and predict the future
List the ingredients of environmental or human health risk.
- Contaminant source
- Release mechanism
- Entry and transport
- Exposure
- Adverse impact
Illustrate the risk assessment framework
- Hazard Identification/Problem Formulation
- Toxicity Assessment
- Exposure Assessment
- Risk Characterization
_____________________ is the term used to describe a potentially harmful situation.
Hazard
______________________ is the stage of the risk assessment process where the dose-response relationship is established
Toxicity assessment
List three (3) levels of risk assessment
- Screening
- Preliminary quantitative
- Detailed quantitative
_______________________ is the level of risk assessment that is completed for all sites.
Screening
List the factors that are important in determining the level of concern associated with a contaminant
- toxicity
- mobility
- persistence
- potential to bioaccumulate or biomagnify -quantity
List the five (5) types of land use. Which type is specific to Alberta?
- Commercial
- Industrial
- Residential/Parklands
- Natural
- Agricultural
What is the purpose of receptor screening?
To identify the most appropriate receptors to be taken forward to the next phases of the risk assessment process.
_________________________ is the term used to describe the physical course a chemical or pollutant takes from the release point to the exposed receptor
Exposure pathway
A _________________________ is a schematic representation of the site showing the applicable sources of chemicals, exposure pathways and receptors
Conceptual model
____________________ is the science that studies toxins
Toxicology
is the process in risk assessment that attempts to determine the dose response relationship
Toxicity Assessment
What are the three ways that chemicals can enter the body?
Ingestion, inhalation, dermal contact
What are the four potential fates of chemicals that enter the body?
- Absorption and distribution
- Metabolism
- Storage
- Excretion
is the term used to describe chemicals that alter the DNA or RNA of cells.
Mutagenic
is the term used to describe chemicals where exposure to even a single molecule of the chemical could cause adverse health impacts.
Non-threshold
The four (4) types of combined effect due to simultaneous exposure to more than one chemical are.
- Additive
- Synergistic
- Antagonistic
- Potentiation
LOAEL is the acronym for __________________________________.
Lowest Observed Adverse Effects Level
NOAEC is the acronym for ___________________________________.
No Observed Adverse Effects Concentration
__________________ is the term used to describe a scientific experiment to determine the toxicity of a substance.
Bioassay
Substances where epidemiological studies show that the chemical is unlikely to cause cancer in humans but where there may be some evidence of carcinogenicity in animals are termed Group _________________ by Health Canada.
Four (IV)
List the concerns raised about applying exposure limits developed using animal bioassays to humans
- Transferability of limits from animals to humans
- Sensitive individuals in the population
- Study deficiencies such as:
- Acute tests exclude long term impacts
- Number of species tested
- Replicability of studies
- Statistical significance of findings
- Duration of the tests
- Exposure route of tests
Why is it likely that animal bioassays will continue to be used for the foreseeable future?
Provide information quickly and cost effectively and epidemiological information may not be available for some chemicals and it is not ethical to test potentially harmful chemicals on humans.
What is the RfC and what does it mean?
The Reference Concentration. Exposure to a chemical below this level in theory would not result in any significant adverse health impacts.
What is the TDI and what does it mean
Tolerable Daily Intake. Exposure to a chemical below this level in theory would not result in any significant adverse health impacts
What is the SF and what does it mean
The SF is the Oral Slope Factor and represents the slope of the extrapolated line representing the dose-response relationship. It is normally represented in terms of risk per mg per kg of body weight per day
What is TD05 and what does it mean
The Tumorigenic Dose that increases the risk of cancer by 5%. Based on the extrapolation of the dose-response relationship, exposure to this dose of a chemical would increase the risk of cancer by 5%.
What is the main advantage of an epidemiological study over an animal bioassay?
Reduced uncertainty as there is no need to extrapolate from animals to humans.
_________________________ is the term used to describe an inadequacy in the design of an experiment or research study which results in findings or conclusions that are not representative of the general population
Bias
__________________________ is the term used to describe factors that are unknown or overlooked in an experiment or research study which distort the cause-effect relationship being studied.
Confounding Factors
A worker is exposed to a chemical 10 hours/day, 5 days/week, 48 weeks/year. What is the exposure term
0.275
What is the exposure term for a resident
Assume 1.0
child playing in a playground is exposed to a contaminant 1 hour/day, 5 days/week, 39 weeks/year. What is the exposure term?
0.022
Toluene is present in well water at 1 mg/L. The water is ingested by residents at a rate of 5 L/day. The residents exposed to toluene are adults (assume 70 kg body weight). What is the exposure to toluene in drinking water
7 x 10-2 mg/kg/day
Calculate the exposure to toluene if the receptor is a worker exposed 10 hours/day, 5 days/week, 48 weeks/year
2 x 10-2 mg/kg/day
Thallium is present in soil at 600 mg/kg. The soil ingestion rate for adults is 20 mg/day. Assuming the receptor is a worker exposed 10 hours/day, 5 days/week, 48 weeks/year, what is the exposure to thallium by soil ingestion
4.7 x 10-5 mg/kg/day
Assuming the information from #6, soil adheres to the skin of receptors at a rate of 8700 mg/day. The absorption factor for skin is 0.2 for thallium. What is the exposure dose for dermal contact with the skin
4.0 x 10-3 mg/kg/day
A study by Health Canada showed that the average adult is exposed to thallium as follows:
•
0.000345 mg/kg/day in air
•
0.000015 mg/kg/day in drinking water
•
0.005056 mg/kg/day in food
a.
What is the total estimated daily intake (TEDI) for thallium?
b.
Using the soil ingestion and dermal exposure, what is the total exposure dose for thallium?
- a. 5.4 x 10-3 mg/kg/day
b. 9.5 x 10-3 mg/kg/day
What are the 2 components of risk?
- The predicted or expected probability that an adverse event will occur.
- The severity or magnitude of the consequences if that event should happen.
List the four elements to Risk.
- The event itself.
- Probability that the event might occur.
- Severity or magnitude of the consequences.
- The exposure time.
Define De Minimus as it pertains to Risk assessments.
About small things. Risks that are to small to be concerned about and therefore considered acceptable.
What are the two main types of risk assessments?
- Human Health Risk Assessment
- Ecological Risk Assessment
Define Risk Assessment.
A scientific technique used to estimate risk posed to human health, plants, animals and the natural environment from exposure to a contaminant.
Describe the differences between Threshold and Non-Threshold hazards.
Threshold chemicals have no adverse effects at low dosages. Non-Threshold indicates that there is no safe dose, exposure to even a single molecule increases the probability receptors will experience an adverse effect.
List and describe the 3 types of Bioassays.
- Acute - a single dose of substance in food, water or concentration for aquatic species.
- Chronic - long term studies done for most if not all of the animals life span.
- Sub-Chronic - Exposure for about ten percent of the animals life span.
What is the formula in calculating exposure assessments?
ED = ( C * IR / BW ) * ET * BAF
What is a LNAPL? Describe it.
Light, Non-aqueous Phase Liquid. A contaminant that floats on top of the water table.
What is a DNAPL? Describe it.
Dense. Non-aqueous Phase Liquid. Contaminant that is denser then water and will continue to sink through water until an impermeable barrier is hit.
The more extensive form of a risk assessment is called what?
A Detailed Quantitative Risk Assessment.
Explain what a screening assessment is.
- Phase 1 site assessment
- Used to initially collect data about the site of study to determine past hazards associated with the site.
- Looks at factors from the past that would affect it’s current state.
