Anne Fairbrother, Randy Wentsel, Bill Wood, Keith Sappington, and Pam Noyes Office of Research and...

Anne Fairbrother, Randy Wentsel, Bill Anne Fairbrother, Randy Wentsel, Bill Wood, Keith Sappington, and Pam NoyesWood, Keith Sappington, and Pam Noyes

Office of Research and DevelopmentOffice of Research and Development

SETAC North America Annual ConferenceSETAC North America Annual Conference

November 2006November 2006

Anne Fairbrother, Randy Wentsel, Bill Anne Fairbrother, Randy Wentsel, Bill Wood, Keith Sappington, and Pam NoyesWood, Keith Sappington, and Pam Noyes

Office of Research and DevelopmentOffice of Research and Development

SETAC North America Annual ConferenceSETAC North America Annual Conference

November 2006November 2006

Framework for Inorganic Framework for Inorganic Metals Risk AssessmentMetals Risk AssessmentFramework for Inorganic Framework for Inorganic Metals Risk AssessmentMetals Risk Assessment

BackgroundBackground

There has been considerable There has been considerable interest in the Agency’s interest in the Agency’s assessments on metals and assessments on metals and metal compoundsmetal compounds

promulgation of the Toxics promulgation of the Toxics Release Inventory (TRI) lead Release Inventory (TRI) lead rulemakingrulemaking

development of the Agency’s development of the Agency’s Waste Minimization Prioritization Waste Minimization Prioritization ToolTool

PBT framework is based on principles PBT framework is based on principles developed for organic substances developed for organic substances that do not apply to metalsthat do not apply to metals

PBT framework does not distinguish PBT framework does not distinguish between metal elements, metal between metal elements, metal compounds, or particulate sizecompounds, or particulate size

There is a major disconnect between There is a major disconnect between the forms selected for toxicity testing the forms selected for toxicity testing and those in the marketplaceand those in the marketplace

Challenge to the PBT Framework as Challenge to the PBT Framework as Applied to MetalsApplied to Metals

BCFs for metalsBCFs for metals vary with species and vary with species and

environmental conditionsenvironmental conditions show an inverse relationship with show an inverse relationship with

concentrationconcentration are not a predictor of toxicityare not a predictor of toxicity

Speciation and bioavailability Speciation and bioavailability are more meaningful than are more meaningful than persistence when evaluating persistence when evaluating hazard potentialhazard potential



PBT framework lacks discriminatory power for metals

All metals would satisfy the All metals would satisfy the criteria to be a PBTcriteria to be a PBT

Metals FrameworkMetals Framework

Develop a cross-Agency Develop a cross-Agency guidance for assessing metal guidance for assessing metal and metal compoundsand metal compounds

discussions within the Agency, discussions within the Agency, with external stakeholders and with external stakeholders and with Congresswith Congress

provide opportunities for external provide opportunities for external input, peer review and cross-input, peer review and cross-Agency involvement Agency involvement

Metals FrameworkMetals Framework

Develop a comprehensive Develop a comprehensive framework that could be the framework that could be the basis of future Agency actionsbasis of future Agency actions

Provide a consistent set of key Provide a consistent set of key guiding principles to be guiding principles to be considered in assessing risks considered in assessing risks posed by inorganic metals posed by inorganic metals

Identify available methods, Identify available methods, models, and approaches for use models, and approaches for use in metals risk assessmentsin metals risk assessments

Foster consistency across EPA Foster consistency across EPA programs and regions programs and regions

Phase I: Metals Phase I: Metals Action Plan Dec 2002 Action Plan Dec 2002

Phase II: Issue PapersPhase II: Issue Papers Aug 2004Aug 2004

ScheduleSchedule

SABSABReviewReview

PeerPeerReviewReview

EnvironEnvironChemistryChemistry

HumanHumanHealthHealth

EcoEcoEffectsEffects

ExposureExposure Bioavail.Bioavail.Bioaccum.Bioaccum.

Phase III: Draft Metals Phase III: Draft Metals Framework June 2004Framework June 2004

Phase IV: Final Document and AgencyPhase IV: Final Document and Agency Implementation Jan 2007Implementation Jan 2007

ScheduleSchedule

Phase III: Draft Metals Phase III: Draft Metals Framework Dec 2004Framework Dec 2004

Peer Input WorkshopPeer Input WorkshopJuly 2004July 2004

SAB Review Feb 2005 - 2006SAB Review Feb 2005 - 2006

InterAgency Review August 2006InterAgency Review August 2006

IntraAgency Review July 2006IntraAgency Review July 2006

Metals and Metalloids of Metals and Metalloids of Primary Interest Primary Interest

AluminumAluminum AntimonyAntimony ArsenicArsenic BariumBarium BerylliumBeryllium BoronBoron CadmiumCadmium ChromiumChromium CobaltCobalt CopperCopper IronIron Lead Lead

ManganeseManganese Mercury Mercury

(inorganic)(inorganic) MolybdenumMolybdenum NickelNickel SeleniumSelenium SilverSilver StrontiumStrontium TinTin ThalliumThallium VanadiumVanadium ZincZinc

Framework TOCFramework TOC

Executive SummaryExecutive Summary

Ch 1 – IntroCh 1 – Intro

Ch 2 – Framework overviewCh 2 – Framework overview

Ch 3 – Environmental Chemistry, Ch 3 – Environmental Chemistry, Transport, and FateTransport, and Fate

Ch 4 – Human HealthCh 4 – Human Health

Ch 5 – Aquatic EcoRiskCh 5 – Aquatic EcoRisk

Ch 6 – Terrestrial EcoRiskCh 6 – Terrestrial EcoRisk

Ch 7 -- ReferencesCh 7 -- References

Ch 1. IntroductionCh 1. Introduction Purpose and audiencesPurpose and audiences Metals Framework ScopeMetals Framework Scope Metals Assessment ContextMetals Assessment Context

National ranking and categorizationNational ranking and categorization National risk assessmentsNational risk assessments Regional and local risk assessmentsRegional and local risk assessments

Key Principles to ConsiderKey Principles to Consider

Categories of Metals Assessments and ApplicableCategories of Metals Assessments and ApplicableEPA Statutory FrameworkEPA Statutory Framework

SiteSite--Specific AssessmentsSpecific Assessments

[CWA, CAA, CERCLA, RCRA][CWA, CAA, CERCLA, RCRA]NationalNational--Scale AssessmentsScale Assessments

ScreeningScreening--LevelLevelAnalysesAnalyses

Criteria/Criteria/Standards DevelopmentStandards Development

[CAA, CWA, SDWA, [CAA, CWA, SDWA, CERCLA, RCRA]CERCLA, RCRA]

Chemical Reviews Chemical Reviews [TSCA, FIFRA, [TSCA, FIFRA, CAA, EPCRA]CAA, EPCRA]

Ranking/Ranking/CategorizationCategorization

[EPCRA, CERCLA, RCRA[EPCRA, CERCLA, RCRATSCA, FIFRA, TSCA, FIFRA,

SDWA, CAA, CWA]SDWA, CAA, CWA]

Complex AnalysesComplex Analyses

ScreeningScreening--LevelLevelAnalysesAnalyses

Complex AnalysesComplex Analyses

PrinciplesPrinciples

Metals are Metals are naturally occurring naturally occurring constituentsconstituents in the environment in the environment and vary in concentrations and vary in concentrations across geographic regions.across geographic regions.

All environmental media have All environmental media have naturally occurring naturally occurring mixturesmixtures of of metals, and metals often are metals, and metals often are introduced into the introduced into the environment as mixtures. environment as mixtures.

Natural occurrence of Natural occurrence of baritebarite

Natural occurrence of barite(USGS)

PrinciplesPrinciples Some metals are Some metals are essentialessential for for

maintaining proper health of maintaining proper health of humans, animals, plants, and humans, animals, plants, and microorganisms.microorganisms.

PrinciplesPrinciples Unlike organic chemicals, metals are Unlike organic chemicals, metals are

neither created nor destroyedneither created nor destroyed by by biological or chemical processesbiological or chemical processes They can transform from one species to They can transform from one species to

another (valence states) and can convert another (valence states) and can convert them between inorganic and organic forms.them between inorganic and organic forms.

The absorption, distribution, The absorption, distribution, transformation, and excretion of a transformation, and excretion of a metal (metal (toxicokineticstoxicokinetics) within an ) within an organism depends onorganism depends on the metalthe metal the form of the metal or metal compoundthe form of the metal or metal compound the organism’s ability to regulate and/or the organism’s ability to regulate and/or

store the metal. store the metal.

Ch 2. Framework Over viewCh 2. Framework Over view

Human Health and Ecological Human Health and Ecological Risk Assessment: Planning and Risk Assessment: Planning and Problem FormulationProblem Formulation

Metal Conceptual ModelMetal Conceptual Model Assessment PhaseAssessment Phase

BioavailabilityBioavailability Characterization of ExposureCharacterization of Exposure Characterization of Effects / Hazard Characterization of Effects / Hazard

AnalysisAnalysis Risk CharacterizationRisk Characterization

Metal Loadings to Media

air

surface water

soil, seds.,

Metal Distribution

in Media

soil, seds., air

Media-based Exposure

Models

ground watersoil, seds., air

Bioaccumulation/TK Models

Metal Distribution

in Tissues

liver, lung,kidney, gill

fur, feather etc.

Residue-based Toxicity Models

Risk (Toxicity)

toOrganism / Individual

mortalitygrowth, repro.

other endpoints

(e.g., mg/kg/d)

diet

Metal Distribution

in Diet

producers1o consumers

BioaccumulationFood Web Model

2o consumers

Dietary ExposureModels

Media-based Toxicity Models

Risks at Higher

Levels of Biological

Organization

populationcommunity

ecosystem

Population, Habitat, Ecosystem

Models

ground watersurface water

ground watersurface water

Dose-basedToxicity Models

Fate & Transport Models

Exposure to Metal

(M1) (M2) (M3) (M4)

(M5)

(M6)

(M7)

(M8)

(M9)

Conceptual Model for Metal Risk AssessmentsConceptual Model for Metal Risk Assessments

Assessment QuestionsAssessment Questions

Principles are translated into Principles are translated into assessment questions to assist assessment questions to assist in their considerationin their consideration

Questions drafted for all Questions drafted for all phases of the risk assessmentphases of the risk assessment

Example Assessment Example Assessment QuestionsQuestions

BACKGROUND: How should background BACKGROUND: How should background (natural and anthropogenic) levels for (natural and anthropogenic) levels for metals be characterized for the selected metals be characterized for the selected spatial scale of the assessment? spatial scale of the assessment?

MIXTURES: Are toxicological effects of MIXTURES: Are toxicological effects of metal mixtures being incorporated in the metal mixtures being incorporated in the effects assessment? effects assessment?

ESSENTIALITY: How will both toxicity and ESSENTIALITY: How will both toxicity and deficiencies of essential metals be deficiencies of essential metals be characterized?characterized?

METAL FORMS: Since environmental METAL FORMS: Since environmental chemistry is a primary factor influencing chemistry is a primary factor influencing metal speciation and subsequent metal speciation and subsequent transport, uptake, and toxicity, how will it transport, uptake, and toxicity, how will it be included in the risk assessment?be included in the risk assessment?

Ch 3. Environmental Chemistry, Ch 3. Environmental Chemistry, Transport, and FateTransport, and Fate

Introduction and TerminologyIntroduction and Terminology Hard and soft acids and basesHard and soft acids and bases TransformationsTransformations Aquatic chemistryAquatic chemistry Ground water and metals mobilityGround water and metals mobility Sediment chemistrySediment chemistry Soil chemistrySoil chemistry Atmospheric behavior / chemistryAtmospheric behavior / chemistry

Metal Transport and FateMetal Transport and Fate Aquatic and terrestrial transport pathwaysAquatic and terrestrial transport pathways Atmospheric fate and transportAtmospheric fate and transport

Bioavailability IssuesBioavailability Issues

Bioavailability of metals Bioavailability of metals variesvaries widelywidely according to the physical, chemical, according to the physical, chemical, and biological conditions under which and biological conditions under which an organism is exposed. an organism is exposed.

Bioavailability should be Bioavailability should be explicitly explicitly incorporatedincorporated into all risk assessments into all risk assessments

Trophic transfer can be an important Trophic transfer can be an important route of exposure for metalsroute of exposure for metals but biomagnification of inorganic forms of but biomagnification of inorganic forms of

metals in food webs is generally not a metals in food webs is generally not a concern in metals assessments concern in metals assessments

BAF/BCF IssuesBAF/BCF Issues

Certain metal compounds are Certain metal compounds are known to bioaccumulate in tissues known to bioaccumulate in tissues and this bioaccumulation can be and this bioaccumulation can be related to their toxicity.related to their toxicity.

The latest scientific data on The latest scientific data on bioaccumulation do not currently bioaccumulation do not currently support the use of bioconcentration support the use of bioconcentration factor (BCF) or bioaccumulation factor (BCF) or bioaccumulation factor (BAF) values when applied as factor (BAF) values when applied as generic threshold criteria for the generic threshold criteria for the hazard potential of inorganic metalhazard potential of inorganic metal

BAF/BCF IssuesBAF/BCF Issues

Single value BAF/BCFs hold the most value for site-specific assessments extrapolation across different exposure

conditions is minimized

For regional and national assessments, BAF/BCFs should be expressed as a function of media chemistry and metal concentration for particular species (or closely related organisms)

Environmental ChemistryEnvironmental Chemistry Metal speciation affectsMetal speciation affects

toxicity, volatilization, photolysis, toxicity, volatilization, photolysis, sorption, atmospheric deposition, sorption, atmospheric deposition, acid/base equilibria, polymerization, acid/base equilibria, polymerization, complexation, electron-transfer reactions, complexation, electron-transfer reactions, solubility and precipitation equilibria, solubility and precipitation equilibria, microbial transformations, and diffusivitymicrobial transformations, and diffusivity

Speciation includesSpeciation includes free metal ions, metal complexes free metal ions, metal complexes

dissolved in solution and sorbed on solid dissolved in solution and sorbed on solid surfaces, and metal species that have surfaces, and metal species that have been co-precipitated in major metal solids been co-precipitated in major metal solids or that occur in their own solids.or that occur in their own solids.

Environmental ChemistryEnvironmental Chemistry

pH and redox potential affect pH and redox potential affect speciationspeciation

Kd valuesKd values

limited use of single values limited use of single values

Aging of metals in media reduces Aging of metals in media reduces bioavailabilitybioavailability

Metal sorption behavior affects Metal sorption behavior affects bioavailabilitybioavailability

Ch 4. Human Health Risk Ch 4. Human Health Risk Assessment for MetalsAssessment for Metals

Metals PrinciplesMetals Principles Human Exposure AssessmentHuman Exposure Assessment

BackgroundBackground BioavailabilityBioavailability Susceptible populationsSusceptible populations Environmental release, transport and fateEnvironmental release, transport and fate Route-specific differences in effectsRoute-specific differences in effects Integrated exposuresIntegrated exposures BiomarkersBiomarkers

Hazard CharacterizationHazard Characterization MixturesMixtures EssentialityEssentiality Forms of metalsForms of metals Toxicokinetics / toxicodynamicsToxicokinetics / toxicodynamics Metal toxicityMetal toxicity Dose-response assessmentDose-response assessment

Risk CharacterizationRisk Characterization

Human HealthHuman Health

The organ or tissue in which metal The organ or tissue in which metal toxicity occurs may differ from the toxicity occurs may differ from the organ or tissue(s) in which the metal organ or tissue(s) in which the metal bioaccumulates and may be bioaccumulates and may be affected by the metal’s kineticsaffected by the metal’s kinetics

Both the exposure route and the Both the exposure route and the form of a metal can affect the form of a metal can affect the metal’s carcinogenic potential and metal’s carcinogenic potential and its noncancer effects its noncancer effects

Sensitivity to metals varies with Sensitivity to metals varies with age, sex, pregnancy status, age, sex, pregnancy status, nutritional status, and geneticsnutritional status, and genetics


Metals attached to small airborne Metals attached to small airborne particles are of primary particles are of primary importance for inhalation importance for inhalation exposures. exposures.

Because the diets of humans and Because the diets of humans and other animals are diverse, there other animals are diverse, there may be wide variability in the may be wide variability in the dietary intake of some metals dietary intake of some metals (e.g., in seafood)(e.g., in seafood) results in temporal, geographic or results in temporal, geographic or

cultural variability of responses cultural variability of responses

Essentiality should be viewed Essentiality should be viewed as part of the overall dose-as part of the overall dose-response relationship for response relationship for those metals shown to be those metals shown to be essentialessential Zinc IRIS document is an Zinc IRIS document is an

exampleexample

RFDs should not be below RFDs should not be below RDAsRDAs


Essentiality and ToxicityEssentiality and Toxicity

NutritionallyEssential Metals

with Potential ToxicEffects at Higher

Doses

Toxic Metals WithPossible Beneficial

Effects

Toxic Metals Withno Known

Beneficial Effects

Cobalt Chromium III Copper Iron Manganese Molybdenum Selenium Zinc

Arsenic Boron Nickel Silicon Vanadium

Aluminum Antimony Barium Beryllium Cadmium Chromium VI Lead Mercury Silver Strontium Thallium Tin

Aquatic Ecological Risk Aquatic Ecological Risk Assessment for MetalsAssessment for Metals

Metals PrinciplesMetals Principles Characterization of ExposureCharacterization of Exposure

BackgroundBackground Forms of metalsForms of metals Exposure pathway analysisExposure pathway analysis Fate and transport of metalsFate and transport of metals Bioavailability and bioaccumulationBioavailability and bioaccumulation

Characterization of EffectsCharacterization of Effects EssentialityEssentiality Toxicokinetics / toxicodynamicsToxicokinetics / toxicodynamics Metal mixturesMetal mixtures Critical body residuesCritical body residues


Terrestrial Ecological Risk Terrestrial Ecological Risk Assessment for MetalsAssessment for Metals

Metals PrinciplesMetals Principles Characterization of ExposureCharacterization of Exposure

Natural occurrence of metalsNatural occurrence of metals Forms of metalsForms of metals Exposure routesExposure routes Soil transport and fate modelsSoil transport and fate models Toxicokinetics / toxicodynamicsToxicokinetics / toxicodynamics Soil invertebrate exposureSoil invertebrate exposure Plant exposurePlant exposure Wildlife exposureWildlife exposure

Characterization of EffectsCharacterization of Effects EssentialityEssentiality Toxicity testsToxicity tests Metal mixturesMetal mixtures Critical body residuesCritical body residues Plant and invertebrate toxicityPlant and invertebrate toxicity Wildlife toxicityWildlife toxicity


EcologicalEcological Background levelsBackground levels refers to those refers to those

concentrations of metals that derive concentrations of metals that derive from natural as well as anthropogenic from natural as well as anthropogenic sources that are not the focus of the sources that are not the focus of the risk assessmentrisk assessment metal concentrations vary widely over metal concentrations vary widely over

space and time space and time are partially responsible for distributions are partially responsible for distributions

of plants and wildlifeof plants and wildlife

EcologicalEcological

FFor aquatic organisms, routes of or aquatic organisms, routes of exposure includeexposure include absorption across respiratory organs, absorption across respiratory organs,

dermal absorption, sediment ingestion, dermal absorption, sediment ingestion, and food ingestionand food ingestion

For terrestrial organisms, routes of For terrestrial organisms, routes of exposure includeexposure include binding to roots, foliar uptake, dermal binding to roots, foliar uptake, dermal

absorption, food, water, and soil absorption, food, water, and soil ingestion, or inhalationingestion, or inhalation


For most metals, the free ionic form is most For most metals, the free ionic form is most responsible for toxicityresponsible for toxicity

Free-ion activity models are useful for Free-ion activity models are useful for establishing relative toxicity among metals in establishing relative toxicity among metals in different mediadifferent media BLMBLM FIAMFIAM

Sediment toxicity is reduced by acid volatile Sediment toxicity is reduced by acid volatile sulfides, organic carbon and other factors sulfides, organic carbon and other factors that bind free ions and decrease that bind free ions and decrease bioavailabilitybioavailability

Soil toxicity is affected by pH, CEC, and % Soil toxicity is affected by pH, CEC, and % organic matterorganic matter


Inorganic metal compounds rarely Inorganic metal compounds rarely biomagnify across three or more biomagnify across three or more trophic levelstrophic levels

Effects addition models are a Effects addition models are a useful first approximation of acute useful first approximation of acute toxicity of metal mixturestoxicity of metal mixtures

Critical body or tissue residues Critical body or tissue residues can be used for effects can be used for effects estimations but few data are estimations but few data are available for metalsavailable for metals

Metals Framework, January, 2007Metals Framework, January, 2007

http://?http://?

Issue papers August 2004Issue papers August 2004

http://cfpub2.epa.gov/ncea/cfm/http://cfpub2.epa.gov/ncea/cfm/recordisplay.cfm?deid=86119recordisplay.cfm?deid=86119

Web SitesWeb Sites

Core Technical PanelCore Technical Panel

Co-leads: Anne Fairbrother ORD/NHEERLCo-leads: Anne Fairbrother ORD/NHEERL Randy Wentsel OW/OSTRandy Wentsel OW/OST

Steering Committee:Steering Committee:Bill WoodBill Wood ORD/NCEA/RAFORD/NCEA/RAFSteve DevitoSteve Devito OEI/OIAAOEI/OIAAAlec McBrideAlec McBride OSWER/OSWOSWER/OSWDave MountDave Mount ORD/NHEERLORD/NHEERLKeith SappingtonKeith Sappington ORD/NCEAORD/NCEA

Pam Noyes Pam Noyes ORD/NCEA/RAFORD/NCEA/RAF

Gary Bangs ORD/NCEA/RAFGary Bangs ORD/NCEA/RAF

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