Test 2 Flashcards
(39 cards)
What is fate and transport?
Fate and transport and interdependent and complex processes related to the travel of environmental contaminants through water, soil, air, biota, and waste materials
What are the four mechanisms of transport?
- Surface water runoff
- Leaching
- Groundwater movement
- Volatilization
Where can transport occur?
Transport of environmental contaminants can occur from a planetary scale down to the molecular scale
What are the major properties of contaminants that affect their transport?
- Water solubility
- Liquid density
- Vapor pressure (higher VP, more evaporation)
- Henry’s law constant (higher constant, higher volization)
- Adsoprtion coefficient
- Octanol / Water partition coefficient
- Bioconcentration factor
- Transformation and degredation rates
What are site-specific considerations that affect transport of contaminant through media?
Climatic conditions, soil type, and presence of biota
Point source vs non point source
Point source: Single point of origin (ex. refinery, pipe, ditch)
Non-Point source: diffused sources (ex. agricultural runoff, urban surfaces)
Primary vs Secondary Pollutant
Primary: directly emitted (ex. plant producing CO2 and SO2 emissions in atmosphere)
Secondary: formed in an atmosphere through physical and chemical conversion of precursors (ex. acidic rain and O3 created from CO2 and SO2)
When is ozone bad?
Ground-level (troposphere) ozone causes smog
What is the formula for risk?
Risk = Hazard x Exposure
What are the four exposure measures?
- Nominal: presence or absence of an agent
- Ordinal: low-medium-high categories
- Interval: categories represent the known interval between high, medium, and low
- Ratio: intervals with a zero, fully quantitative scale (ppm, mg/m3)
Variability of Exposure
Exposures have large variability and vary over time, place, and pollution sources
What are the characteristics of exposure data?
Lognormal distribution
Sources of variability in environmental exposure data are ….
Random and systematic
When do biases occur in data?
When certain characteristics are assumed to apply as averages in epidemiology studies
What did Paracelsus say is the basis of toxicology?
The dose makes the poison; the toxicant dose can impact the degree of the toxicant effect
What can lipophilic compounds do?
Lipophilic compounds can bioaccumulate and biomagnify and therefore, reside within an organism over a longer period of time
What is an example of lipophilic, persistent compounds?
Organocholrine pesticides
What does the toxicokinetics of compounds determine?
The toxicokinetics of compounds can determine the residence time of the compound in an organism, whether or not the compound is metabolized to a more toxic agent, and where and how the compound produces its effects
What is the relationship between water solubility and residence time in an organism?
Water-soluble compounds will have a shorter residence time in an organism
Example: organophosphate pesticides are more water soluble and will not persist in an organism over time
ADME
- Absorption
- Distribution
- Metabolism
- Excretion
What are the three major approaches for toxicant classification?
- Chemical class
- Exposure Source
- Target organ
What are the four key components of Risk Assessment?
- Hazard identification
- Dose-Response assessment
- Exposure assessment
- Risk characterization
What is the purpose of risk assessment?
The purpose of risk assessment is to provide related information to risk managers, specifically, policymakers and regulators, so that the best possible decision can be made
What is risk assessment?
Risk assessment is the evaluation of the likelihood, magnitude, and uncertainty of risks. It is a systematic approach to estimating the chance of adverse health effects resulting from exposure to an environmental stressor
