Transcript Ecological Risk Assessment

Ecological Risk Assessment
Definition Evaluates the likelihood that adverse
ecological effects may occur or are occurring as a result
of exposure to one or more stressors.
Legislation and Ecological Risk
 NEPA
 FIFRA
 TSCA
 FWPCA
 CERCLA
Levels of Organization
Genetic
 Cell
 Tissue
 Species-Individual
 Population
 Community
 Ecosystem
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Bioaccumulation
 Bioconcentration
 Biomagnification
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Process
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Screening-level problem formulation and ecological effects eval.
Screening-level exposure estimate and risk calculation*
Baseline risk assessment, assessment endpoint selection
Study design and DQO process*
Verification of field sampling design
Site investigation and data analysis
Risk characterization
Risk management*
*Scientific/Management Decisions
Problem Formulation
 Qualitatively evaluate contaminant release,
migration, and fate
 Identify:
Contaminants of concern
Receptors
Complete exposure pathways
Known effects
Endpoint selection
 Develop conceptual model
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Characterization of
Contaminants
 Documentation of all releases
Volume
Duration
Release Mechanism
 Routes of migration
Characterization of
Contamination
 Evaluate physiochemical properties
Solubility
Bioaccumulation potential
 Mechanisms of pathways
Spatial aspects
Temporal aspects
Environmental Receptors
 Characterize receptors
Relevant species (e.g. endangered)
Life history
Feeding habits
Habitat preference
Complete Exposure Pathways
 Source
 Route of exposure
Ingestion
Inhalation
Dermal absorption
 Exposure point
Concentrations
Ecological Effects Assessment
 Literature
 Toxicity testing
 Field studies
Assessment Endpoints
 A formal expression of the actual environmental
value to be protected
Reduction of key population
Disruption of community structure
 Long-term persistence, abundance, or
production of populations of significant species
or ecological relevant habitats
Examples of Assessment
Endpoints
 Population- brown trout in reservoir
Extinction
Abundance
 Communities- aquatic food web
Market sport value
Recreational quality
 Ecosystems-entire reservoir
Productivity or function
Measurement Endpoints
A physical, chemical, biological, or ecological condition
that can be quantified
 Measured in the laboratory or field
 Must be associated with an assessment endpoint
 Creates a method to meet the assessment endpoint
that is quantifiable
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Examples of Measurement
Endpoints
 Individual
Death
Melanomas
Abnormal behavior
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Population
Occurrence
Abundance
Percent affected
Examples of Measurement
Endpoints
 Community
Number of species
Species diversity
 Ecosystem
Productivity
Nutrient cycling
Developing a Conceptual Site
Model
 Receptors
 Contaminant sources
 Routes of exposure
 Primary and secondary pathways
 Contamination media
Analysis Phase of ERA
 Determination of Ecological Effects
Ecological Response Analysis/Ecotox Assessment
Stressor response profile
Effects linked to assessment endpoints
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Characterization of Ecological Exposure
Exposure pathways
Receptor characteristics
Exposure concentrations
Contribution of Toxicity Tests in
ERA
 Bioavailability of stressors
 Aggregate toxic effects for all stressors
 Development of new toxicity information
 Characterization of nature of toxic effect
 Distribution of toxicity
 Biomonitoring
Toxicity Tests used in ERAs
 Freshwater Aquatic and Sediment Tests
Daphnia, minnow, algae, amphipod or midge
 Marine and Estuarine Tests
Sheepshead minnow, silverside, mysid shrimp
 Terrestrial Tests
Earthworm, collembola, seed germination and root
elongation, growth on rooted plants, FETAX (Frog
embryo teratogenesis assay), avian toxicity tests
Toxicological Endpoints
 NOAEL = No observable adverse effect level
 LOAEL
 LD50, LC50, EC or ED, effective conc or dose
Endpoints with Chronic testing
 Growth
 Reproduction
 Nerve function impairment
 Immobility or behavioral changes
 Development of morphological abnormalities
In-situ Toxicity Tests
 Expose test organisms on-site
 Measures bioavailability
 Organisms are exposed to natural stressors
 Uncontrolled environment
Analysis Phase
Characterization of Receptors
 Life History
 Feeding habits, Diet, and Food sources
 Habitat Preferences
 Energy Requirements, Physiological and
Metabolic pathways
 Pathway analysis and/or food chain
Ecological effects and exposure
Stressor Response
Analysis
 Link effects, dose, or
toxicity value to
endangered species
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Characterize the
receptors
 Determine exposure
routes and pathways
 Measure or estimate
exposure point conc.
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Risk Characterization
 Final step
 Integration process
 Estimation of risk- quantitative or qualitative
Hazard quotient
Probabilistic risk estimates
Weight of evidence
 Should include an Uncertainty Analysis
Hazard Quotient Method
 Provides a point estimate and relates stressor
concentrations with effects levels
 Hazard Quotient (HQ) = EEC/ TEC
EEC
TEC
Expected Exposure Conc.
Toxicological Endpoint Conc.
(NOAEL or LD 50)
Hazard Quotient Method
 Represents ratio of safe to unsafe exposure
 If HQ exceeds unity, toxicity threshold is
exceeded and an adverse toxicological effects is
expected
 Multiple stressors can be summed for same
pathways to determine an Hazard Index (HI)
 Range of HQs or HIs