ECOFRAM: Aquatic Risk Assessment
Jeffrey Giddings
Springborn Laboratories Inc.
Paul Hendley
Zeneca Ag Products.
On this Page
- Risk Quotient Equation
- Probabilistic Risk Characterization
- Exposure Distribution
- Exposure Analysis
- Probability of Exceeding LC50
- Probability of Mortality
- Extrapolation to Population Effect
- Another Endpoint: the PR50
- Probability of Population Decline
- Distribution of Species Sensitivity
- Probability of Affecting Species
- Pulsed Exposure
- Assessing Effects of Pulsed Exposures
- Other Components of Effects Analysis
- Outstanding Issues
- Summary of Tools for Effects Assessment
- Risk Assessment Process
Risk Quotient = Exposure Concentration / Effect Concentration
Probabilistic Risk Characterization
![graph of a curve with y-axis of probability of occurrence and x-axis of magnitude of effect](../gif/sra_fig1.gif)
Probabilistic Risk Characterization
Exposure Distribution
![graph of connected points with y-axis of exceedance frequency and x-axis of concentration (mg/L)](../gif/sra_fig2.gif)
Exposure Distribution
Exposure Analysis
Step 1: Deterministic; edge of field/pond, worst case (GENEEC)
Step 2: Probabilistic; more chemical information; variation with weather, region, receiving water type (PRZM/EXAMS)
Step 3: Probabilistic; landscape and watershed factors
Probability of Exceeding LC50
![graph of connected points with y-axis of exceedance frequency and x-axis of concentration (mg/L) and vertical line representing LC50 and intersecting horizontal line representing probability of exceeding LC50](../gif/sra_fig3.gif)
Probability of Exceeding LC50
Probability of Mortality
![3 graphs: first of connected points with y-axis of frequency and x-axis of concentration; second of connected points with y-axis of mortality (%) and x-axis of concentration; third a curve with y-axis of probability and x-axis of mortality (%)](../gif/sra_fig4.gif)
Probability of Mortality
Extrapolation to Population Effect
![3 graphs: first of connected points with y-axis of mortality (%) and x-axis of concentration; second a curve with y-axis of pop. decline (%) and x-axis of mortality (%); third a curve with y-axis of pop.decline (%) and x-axis of concentration](../gif/sra_fig5.gif)
Extrapolation to Population Effect
Another Endpoint: the PR50
![graph of curve with y-axis of pop.decline (%) and x-axis of concentration. line indicators included: vertical line of PR50 and horizontal line of 50% population reduction](../gif/sra_fig6.gif)
Another endpoint: the PR50
Probability of Population Decline
![3 graphs: first of connected points with y-axis of frequency and x-axis of concentration; second a curve with y-axis of pop. decline (%) and x-axis of concentration; third a curve with y-axis of probability and x-axis of pop.decline (%)](../gif/sra_fig7.gif)
Probability of Population Decline
Distribution of Species Sensitivity
![graph of distribution of LC50's for chlorpyrifos for arthropods and for fish. y-axis of sensitivity rank (percentile) and x-axis of concentration (ng/L)](../gif/sra_fig8.gif)
Distribution of LC50's for Chlorpyrifos
Probability of Affecting Species
![3 graphs: first of connected points with y-axis of frequency and x-axis of concentration; second of best-fit line through points with y-axis of % of LC50s and x-axis of concentration; third a curve with y-axis of probability and x-axis of species affected (%)](../gif/sra_fig9.gif)
Probability of Affecting Species
Pulsed Exposure
Diazinon Concentrations
San Joaquin River at Laird Park
1991-1992
![graph of connected points with y-axis of diazinon concentration (ng/L) and x-axis of months from 10/91 to 10/92](../gif/sra_fig10.gif)
Assessing Effects of Pulsed Exposures
Time-to-event analysis
Laboratory toxicity tests simulating simplified pulses
Uptake / depuration models linked to critical body residue data
Other Components of Effects Analysis
Chronic toxicity
Reproductive effects
Sediment exposure
Behavioral endpoints
Outstanding Issues
Overall ecosystem damage
extrapolation from populations to ecosystems
microcosms and mesocosms provide insight
Mixtures, multiple stressors
Summary of Tools for Effects Assessment
Time-to-Event Analysis
Pulsed Exposures
Population Models
Sensitivity Distributions
Sediment Toxicity Evaluation
Chronic Toxicity Tests
Mesocosms and Microcosms
Behavioral Toxicity Tests
Risk Assessment Process
![flow diagram of step 1 and step 2 of process with headings: aquatic effects, process, aquatic exposure, and scenario / scale](../gif/sra_fig11.gif)
Risk Assessment Process (Steps 1 and 2)
Risk Assessment Process (Steps 3 and 4)
![flow diagram of step 3 and step 4 of process with headings: aquatic effects, process, aquatic exposure, and scenario / scale](../gif/sra_fig12.gif)