Risk Analysis of Contaminated Sites: Human Health and Ecological Risk Assessment F. Quercia, ANPA...
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Risk Analysis of Contaminated Sites:Human Health and Ecological Risk
AssessmentF. Quercia, ANPA
Workshop ICS/UNIDO - Fundacion Mamonal
Environmental Pollution and Applicability of Remediation Technologies in Latin-American Countries
Cartegena des India, 4-7 Dec., 2000
Cartagen des India, 4-7.12.2000 3
Land use oriented and risk-based soil management
M ob ile p ollutio n:C le a n up b y coste ffec tivemea ns
Iimmo bile p ollution:C le a n up only if the re iis a c learb enefit
C ontac t zone . Q ua lity re la ted to la nduse
Cartagen des India, 4-7.12.2000 4
DefinitionsDefinitions
• Risk assessment is an objective, scientific evaluation of the likelihood of unacceptable impacts to human health and the environment
• Risk is the combination of:
– exposure to toxic substances
– hazard/toxicity of substances
Cartagen des India, 4-7.12.2000 5
Human HealthRisk Assessment
Cartagen des India, 4-7.12.2000 6
Quantitative Risk AssessmentForward versus Backward R.A.
Quantitative orAbsolute R.A.
• FW: Assesses baseline risks related to site contamination levels
• BW:Defines generic guideline values and site-specific clean up goals related to target risk levels
Cartagen des India, 4-7.12.2000 7
Risk Assessment: forward procedure
ObservedConcentration
EstimatedExposure
EstimatedRisk
Baseline Risk AssessmentBaseline Risk Assessment
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I. Hazard Identification
II.Exposure Assessment
Desk StudyPrelim. CSM
Exploratory SIRefined CSM
Identification of sources,pathways and receptors
Assess source - pathway - receptorlinkages and estimate exposure
III.Dose/Response Assessment
IV: RiskAssessment
Assesscontaminantshuman toxicity
Combine exposureand toxicologicalevaluations
NoteCSM = conceptual site model
Cartagen des India, 4-7.12.2000 9
Source-pathway-receptorSource-pathway-receptor
one or more routes or means by, or through, which a receptor is being exposed to, or affected by, a contaminant or could be so exposed or affected
Pathway
a substance which has the potential to cause harm to human health or the environment
Source
Receptoran individual which is being, or could be, harmed by the source
IDENTIFY AND Characterize S - P - R
TO BUILD SITE CONCEPTUAL MODEL
IDENTIFY AND Characterize S - P - R
TO BUILD SITE CONCEPTUAL MODEL
Cartagen des India, 4-7.12.2000 10
SourcesSources
Free / immiscible product
Water phase with dissolved contamination
Air phase with vapours
Solid phase with adsorbed contamination
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Risk estimation and evaluationRisk estimation and evaluation
• Uncertainties– Contamination data
• chemical species• concentrations• spatial and temporal effects
– Characteristics of the sub-surface
– Existence/characteristics of pathways
– Identity and location of receptors - now and in the future
– Fate and transport modelling• model selection• validation
– Exposure assessment
– Toxicology
Cartagen des India, 4-7.12.2000 12
ChallengesChallenges
• Public acceptability of risk-based approach• Uncertainty, sensitivity and conservatism• Validation• Information overload
– hundreds of R&D projects
– hundreds of publications
– matching research to need
• Integration of different aspects• Availability of practical “tools”
Cartagen des India, 4-7.12.2000 13
Characterize Characterize SourcesSources::
map of lead map of lead concentration concentration in surface soil in surface soil (<1,5 m deep)(<1,5 m deep)
Characterize Characterize SourcesSources::
map of lead map of lead concentration concentration in surface soil in surface soil (<1,5 m deep)(<1,5 m deep)
584620m 584660m 584700m 584740m 584780m
9688
80m
9689
20m
9689
60m
9690
00m
9690
40m
0
500
50000
300000
notinterpolatedarea
mg/kg d.w.
100
1000
100000
Hazard Assessment: Spot Contaminants of Concern
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Exposure Assessment
Objectives:
• assess contaminant concentration and exposure
to contact media at receptor contact points
Data and tools:
• data from source, site and receptor characterization
. conceptual model parametrization
. use of fate and transport (F&T) models
Cartagen des India, 4-7.12.2000 15
Data for Exposure Assessment• Chemicals: Chemicals: chemical and physical parameters describing chemical and physical parameters describing
environmental mobility, persistency, volatility, bioaccumulation environmental mobility, persistency, volatility, bioaccumulation potentialpotential
• Site/pathways: Site/pathways: physical/chemical parameters describing local soil, physical/chemical parameters describing local soil, air and water resources conditionsair and water resources conditions
• Receptors: Receptors: data describing land use and receptor exposure data describing land use and receptor exposure characteristics ( exp. routes and parameters)characteristics ( exp. routes and parameters)
Choose Contaminants of ConcernChoose Contaminants of Concern Choose relevant pathwaysChoose relevant pathways Choose receptors and locationChoose receptors and location
---------------------------------------------------------------------------------------
Cartagen des India, 4-7.12.2000 16
Exposure Scenario for residential useExposure Scenario for residential use
Transport of leachate to groundwater
Drinking water consumptionDust inhalation
Vapor inhalation
Transport of vapors
Dermal contactSoil ingestion
Vapors and dust inhalation
Groundwater flow
Cartagen des India, 4-7.12.2000 17
Exposure flowchartExposure flowchart
Soil
Groundwater
Air
Groundwatertransport
Drinking wateringestion
Soil ingestion
Dermalcontact
Vapour and dustindoor and outdoorinhalation
SourcesMigrationroutes
Exposure pathways
Air diffusion and dispersion
Industrial
Receptors
Residential
Cartagen des India, 4-7.12.2000 18
AT BW
ED EF CR CE
E = Exposure [mg/kg - day]CR = Contact rate [mg/day]EF = Exposure frequency [day/year]ED = Exposure duration [year]BW = Body weight [kg]AT = Averaging time [year]C = Concentration of contaminant in soil [mg/kg]
Exposure AssessmentExposure Assessment
Cartagen des India, 4-7.12.2000 19
UFxMF
RfD NOAELdose (mg/kg/day)
response
a
SF
response
dose (mg/kg-day)
Carcinogenic effects
b
Toxic effects
RfD = Reference Dose (or TDI) for threshold substances [mg/kg - day]
SF = Slope Factor (or CPS) for non-threshold substances [1/(mg/kg - day)]
RfD = Reference Dose (or TDI) for threshold substances [mg/kg - day]
SF = Slope Factor (or CPS) for non-threshold substances [1/(mg/kg - day)]
Dose/Response (Toxicity) Assessment
Dose/Response (Toxicity) Assessment
Cartagen des India, 4-7.12.2000 20
Cartagen des India, 4-7.12.2000 21
Risk Assessment Risk Assessment
RISK = EXPOSURE x TOXICITYRISK = EXPOSURE x TOXICITY
Threshold non-cancer substances :
TDI
EHI
HI = Hazard Index E = Chronic Exposure[mg/kg-day]
TDI = Toxicity [mg/kg-day]
Non-threshold cancer substances:
SFER R = incremental lifetime cancer risk
E = Chronic Lifetime Exposure [mg/kg-day], SF = Toxicity [1/(mg/kg-day)]
Acceptable Risk Criteria: HI = 1R = 1E-6 1E-4
Cartagen des India, 4-7.12.2000 22
Generic versus site-specific R.A.
• Generic R.A. implies conservative assumptions of potential exposure scenarios, site, contaminants and receptor properties
• Site-specific R.A. implies investigations for collection of local environmental data, construction of conceptual model with actual exposure scenarios
Cartagen des India, 4-7.12.2000 2334
Risk assessment: backward procedure
Acceptable Risk
AcceptableDose
AcceptableConcentration
Cartagen des India, 4-7.12.2000 24
Backward tiered procedure to assess remediation goals from target risk levels
Generic Risk Assessment
computes
Guideline Screening or Trigger values
(for most sensitive or different landuses)
Tier 1 site concentrations exceed Guideline values
Site Specific Risk Assessment
Tier 2 computes
Site Specific Clean up objectives
Cartagen des India, 4-7.12.2000 25
ASTM/RBCA
Tiered procedure
ASTM/RBCA
Tiered procedure
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ASTM/RBCA
• Standard ASTM E1739/95 and PS104/98 for risk-based corrective actions on contaminated sites
• Streamlined tiered procedure for decision making• Tier1 develops RBSLs (Risk-Based Screening Levels)
look-up tables for each pathway against which site concentrations are compared
• Tier 2 and Tier3 develop SSTLs (Site specific Target Levels) as site-specific cleanup objectives
Cartagen des India, 4-7.12.2000 27
Main features of RBCA
• Risk protection level is the same at each Tier
• As data from investigation increase more focused quality objectives are defined
• Tier 1 receptor location is on site on top or below source area according to a conservative assumption
• Tier 2 and 3 receptor position may be at actual location (compliance point)
Cartagen des India, 4-7.12.2000 28
Tier 1: How Soil RBSL are definedTier 1: How Soil RBSL are defined
• For each chemical RBSL are defined for different land uses, i.e.:
. residential/agricolture/recreational . commercial/industrial . groundwater extraction for drinking• The following pathways may be included: . soil ingestion . dermal contact . outdoor and indoor dust inhalation . indoor and outdoor dust inhalation . groundwater drinking• Target receptor for each land use is located right above
the contaminated soil source
• For each chemical RBSL are defined for different land uses, i.e.:
. residential/agricolture/recreational . commercial/industrial . groundwater extraction for drinking• The following pathways may be included: . soil ingestion . dermal contact . outdoor and indoor dust inhalation . indoor and outdoor dust inhalation . groundwater drinking• Target receptor for each land use is located right above
the contaminated soil source
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Groundwater protection : Tier 2 compliance point
Point ofcompliance
(edge of site)
compliance point (receptor) might be located at some distance from the source
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Ecological Risk Assessment(ERA)
Cartagen des India, 4-7.12.2000 31
32Cartagen des India, 4-7.12.2000
EEC ProcedureIdentificazione
dell'Hazard
Valutazionedell'Esposizione:Stima del PEC
Valutazione tossicologica:Stima del PNEC
PEC/PNEC
>1
Altri test odati possonoabbassare ilPEC/PNEC
Misure diriduzione delrischio
Test e dati
addizionali
>1PEC/PNEC
Non occorronoaltri test o misure diriduzione del rischio
No
Si
No
Si
Non occorronoaltri test o misure diriduzione del rischio
NoSi
Cartagen des India, 4-7.12.2000 33
Available Tools
• Ecotoxicological tests data: chronic NOEC/LOEC or acute LEC data from experiments (for screening values)
• PNEC statistical extrapolations from toxicity data (for screening values)
• Biological assays (site-specific)• Biomonitoring (site-specific)• Biomarkers (site-specific)
Cartagen des India, 4-7.12.2000 34
Example:The Netherlands
• Generic risk assessment
(potential risks) for the
development of
Intervention Values, Target Values and Soil use specific Remediation Objectives
• Site specific risk assessment (actual risks) for deciding about urgency of remediation and priorities
Cartagen des India, 4-7.12.2000 35
Intervention Values
• Indicate a serious contamination
• Human health risk protection criteria:TDI and 1E-6/year excess cancer risk residential with vegetable garden exposure
scenario (multifunctional) soil ingestion, inhalation, crop consumption
• Ecological risk protection criteria: HC50 (protection of 50% species) derived by
NOEC (No Observed Effect Concentration), LOEC (Lowest Observed EC)or LEC (Lethal EC)data
adjustment to soil clay content and organic matter
Cartagen des India, 4-7.12.2000 36
Target Values
• Indicate a clean soil
• Ecological risk protection criteria: negligible risk level:1% of HC5 (protects
95% of species) negligible risk level soil concentration is
summed to background value for metals
Cartagen des India, 4-7.12.2000 37
Ecotoxicological risk-based criteria
Response
Dose
NOEC
1] Compute mean and SD of log NOEC2] Estimate the frequency distribution
of log NOEC
safety factor
Intervention value
5%50%log NOEC
Target value
No Observed Effect Concentrations fordifferent species are used to estimate afrequency distribution of NOEC's on alogarithmic scale. Percentiles (5% and50%) are used to derive target andintervention values.
Cartagen des India, 4-7.12.2000 38
Soil-use based Remediation Objectives
• Generic criteria for top soil, non-mobile pollutants and following land uses:
Residential and recreational green areasNon-recreational public green areasBuilt-in and paved areasAgricultural areas and nature reserves
• Objectives protect from both human health and ecotoxicological risks
Cartagen des India, 4-7.12.2000 39
Site-specific Risk Assessment
• For remediation urgency:• Assess site-specific risk by CSOIL model adapted
to local site exposure scenario• Assess ecological risks by pragmatic procedure
based on:area sensitivityHC50 site area for biodiversity preservationbioassays
Note: use of risk assessment to develop site-specific remediation goals is not yet regulated
Note: use of risk assessment to develop site-specific remediation goals is not yet regulated
Cartagen des India, 4-7.12.2000 40
Ecological Risk Assessment (ERA) needs
• An analytical framework is needed
• Limited experience with terrestrial ecosystems is available
• Ecosystem health needs to be defined
• Fit for use and land use based soil ecological objectives are seeked
• Site specific ERA approaches are needed
Cartagen des India, 4-7.12.2000 41
RiskRisk estimation and evaluation estimation and evaluation
• Uncertainties
– Contamination data
• chemical species
• concentrations
• spatial and temporal effects
– Characteristics of the sub-surface
– Existence/characteristics of pathways
– Identity and location of receptors - now and in the future
– Fate and transport modelling
• model selection
• validation
– Exposure assessment
– Toxicology
Cartagen des India, 4-7.12.2000 42
ChallengesChallenges
• Public acceptability of risk-based approach
• Uncertainty, sensitivity and conservatism
• Validation
• Information overload
– hundreds of R&D projects
– hundreds of publications
– matching research to need
• Integration of different aspects
• Availability of practical “tools”