Ecological Risk AssessmentEcological 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 RiskLegislation and Ecological Risk

NEPA FIFRA TSCA FWPCA CERCLA

Levels of OrganizationLevels of Organization Genetic Cell Tissue Species-Individual Population Community Ecosystem

Bioaccumulation Bioconcentration Biomagnification

ProcessProcess 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 FormulationProblem Formulation Qualitatively evaluate contaminant release,

migration, and fate Identify:

Contaminants of concernReceptorsComplete exposure pathwaysKnown effects

Endpoint selection Develop conceptual model

Characterization of ContaminantsCharacterization of Contaminants

Documentation of all releasesVolumeDurationRelease Mechanism

Routes of migration

Characterization of ContaminationCharacterization of Contamination

Evaluate physiochemical propertiesSolubilityBioaccumulation potential

Mechanisms of pathwaysSpatial aspectsTemporal aspects

Environmental ReceptorsEnvironmental Receptors

Characterize receptorsRelevant species (e.g. endangered)Life historyFeeding habitsHabitat preference

Complete Exposure PathwaysComplete Exposure Pathways

Source Route of exposure

IngestionInhalationDermal absorption

Exposure pointConcentrations

Ecological Effects AssessmentEcological Effects Assessment

Literature Toxicity testing Field studies

Assessment EndpointsAssessment Endpoints

A formal expression of the actual environmental value to be protected

Reduction of key populationDisruption of community structure

Long-term persistence, abundance, or production of populations of significant species or ecological relevant habitats

Examples of Assessment EndpointsExamples of Assessment Endpoints Population- brown trout in reservoir

ExtinctionAbundance

Communities- aquatic food webMarket sport valueRecreational quality

Ecosystems-entire reservoirProductivity or function

Measurement EndpointsMeasurement 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 EndpointsExamples of Measurement Endpoints

IndividualDeathMelanomasAbnormal behavior

PopulationOccurrenceAbundancePercent affected

Examples of Measurement EndpointsExamples of Measurement Endpoints

CommunityNumber of speciesSpecies diversity

EcosystemProductivityNutrient cycling

Developing a Conceptual Site ModelDeveloping a Conceptual Site Model

Receptors Contaminant sources Routes of exposure Primary and secondary pathways Contamination media

Analysis Phase of ERAAnalysis Phase of ERA

Determination of Ecological EffectsEcological Response Analysis/Ecotox AssessmentStressor response profileEffects linked to assessment endpoints

Characterization of Ecological ExposureExposure pathwaysReceptor characteristicsExposure concentrations

Contribution of Toxicity Tests in ERAContribution 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 ERAsToxicity 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 EndpointsToxicological Endpoints

NOAEL = No observable adverse effect level LOAEL LD50, LC50, EC or ED, effective conc or dose

Endpoints with Chronic testingEndpoints with Chronic testing

Growth Reproduction Nerve function impairment Immobility or behavioral changes Development of morphological abnormalities

In-situ Toxicity TestsIn-situ Toxicity Tests

Expose test organisms on-site Measures bioavailability Organisms are exposed to natural stressors Uncontrolled environment

Analysis PhaseCharacterization of ReceptorsAnalysis 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

Ecological effects and exposureEcological 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 CharacterizationRisk Characterization

Final step Integration process Estimation of risk- quantitative or qualitative

Hazard quotientProbabilistic risk estimatesWeight of evidence

Should include an Uncertainty Analysis

Hazard Quotient MethodHazard Quotient Method

Provides a point estimate and relates stressor concentrations with effects levels

Hazard Quotient (HQ) = EEC/ TECEEC Expected Exposure Conc.TEC Toxicological Endpoint Conc.

(NOAEL or LD 50)

Hazard Quotient MethodHazard 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