Ecological Risk Assessment

1. 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.

2. Legislation and Ecological Risk • NEPA • FIFRA • TSCA • FWPCA • CERCLA

3. Genetic Cell Tissue Species-Individual Population Community Ecosystem Bioaccumulation Bioconcentration Biomagnification Levels of Organization

4. 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

5. Problem Formulation • Qualitatively evaluate contaminant release, migration, and fate • Identify: • Contaminants of concern • Receptors • Complete exposure pathways • Known effects • Endpoint selection • Develop conceptual model

6. Characterization of Contaminants • Documentation of all releases • Volume • Duration • Release Mechanism • Routes of migration

7. Characterization of Contamination • Evaluate physiochemical properties • Solubility • Bioaccumulation potential • Mechanisms of pathways • Spatial aspects • Temporal aspects

8. Environmental Receptors • Characterize receptors • Relevant species (e.g. endangered) • Life history • Feeding habits • Habitat preference

9. Complete Exposure Pathways • Source • Route of exposure • Ingestion • Inhalation • Dermal absorption • Exposure point • Concentrations

10. Ecological Effects Assessment • Literature • Toxicity testing • Field studies

11. 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

12. 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

13. 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

14. Examples of Measurement Endpoints • Individual • Death • Melanomas • Abnormal behavior • Population • Occurrence • Abundance • Percent affected

15. Examples of Measurement Endpoints • Community • Number of species • Species diversity • Ecosystem • Productivity • Nutrient cycling

16. Developing a Conceptual Site Model • Receptors • Contaminant sources • Routes of exposure • Primary and secondary pathways • Contamination media

17. 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

18. 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

19. 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

20. Toxicological Endpoints • NOAEL = No observable adverse effect level • LOAEL • LD50, LC50, EC or ED, effective conc or dose

21. Endpoints with Chronic testing • Growth • Reproduction • Nerve function impairment • Immobility or behavioral changes • Development of morphological abnormalities

22. In-situ Toxicity Tests • Expose test organisms on-site • Measures bioavailability • Organisms are exposed to natural stressors • Uncontrolled environment

23. Analysis PhaseCharacterization of Receptors • Life History • Feeding habits, Diet, and Food sources • Habitat Preferences • Energy Requirements, Physiological and Metabolic pathways • Pathway analysis and/or food chain

24. 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. Ecological effects and exposure

25. 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

26. Hazard Quotient Method • Provides a point estimate and relates stressor concentrations with effects levels • Hazard Quotient (HQ) = EEC/ TEC • EEC Expected Exposure Conc. • TEC Toxicological Endpoint Conc. • (NOAEL or LD 50)

27. 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