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  Bioaccumulation  Bioconcentration  Biomagnification

Process  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

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

Examples of Measurement Endpoints  Individual Death Melanomas Abnormal behavior  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  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  Characterize the receptors  Determine exposure routes and pathways  Measure or estimate exposure point conc.

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 EECExpected Exposure Conc. TECToxicological 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