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European Risk Model Comparison Study

European Risk Model Comparison Study. Sponsored by NICOLE. Wouter Gevaerts, Arcadis Belgium Karen Van Geert, Arcadis Belgium Matt Gardner, Arcadis UK. Soil Source (mg/kg). General overview. Receptors. 50m. Soil vapour (mg/m³). Sand. GW Source (mg/l). Plume. Groundwater Pathway.

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European Risk Model Comparison Study

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  1. European Risk ModelComparison Study Sponsored by NICOLE Wouter Gevaerts, Arcadis Belgium Karen Van Geert, Arcadis Belgium Matt Gardner, Arcadis UK

  2. Soil Source (mg/kg) General overview Receptors 50m Soil vapour (mg/m³) Sand GW Source (mg/l) Plume Groundwater Pathway Sand

  3. Risk Assessment Process: conceptual model Human risk Human risk Source Pathway Receptor Ecological risk Ecological risk Spreading risk • Chemicals • Concentrations • Toxicity • Exposure • Transport

  4. SOIL DISTRIBUTION SOIL FRACTIONS SOIL AIR CONCENTRATION PORE WATER CONCENTRATION UPTAKE BY/DEPOSITION ON VEGETATION TRANSPORT TO SURFACE SOIL TRANSPORT TO SURFACE WATER TRANSPORT TO GROUNDWATER PERMEATION INTO DRINKING WATER DRINKING WATER TRANSPORT PROCESSES CATTLE DILUTION IN INDOOR AIR DILUTION IN OUTDOOR AIR MILK/ MEAT INGESTION, INHALATION AND DERMAL CONTACT SOIL AND DUST (INDOOR) INGESTION, INHALATION AND DERMAL CONTACT SOIL AND DUST (OUTDOOR) INHALATION INDOOR AIR INHALATION OUTDOOR AIR DIRECT EXPOSURE DRINKING WATER MILK/ MEAT VEGETATION INDIRECT EXPOSURE

  5. Reasons for Comparative Study of Risk models • NICOLE advocate risk-based approach to land management, but: • Many member states develop own models • Differences in model results can be orders of magnitude • Poor understanding of differences may undermine credibility of risk assessment

  6. Sponsors Akzo Nobel BNFL BP Fortum ICI JM Bostad Acknowledgements • NICOLE • Powergen • SecondSite Property • Shell Global Solutions • Solvay • TotalFinaElf • SKB, Netherlands • Kemakta, Sweden • UK Environment Agency • RIVM, Netherlands • VITO, Belgium Peer Review Team Consultant • Arcadis

  7. Objectives • Compare human health risk models used in Europe to • Increase awareness/understanding of variability • Provide confidence in decision making • Compare model results to explain output differences - not to show which is better • Generic site with standardised inputs • Real test cases using model defaults • Determine whether fate and transport codes in models are conservative screening tools

  8. Countries and Models • Austria No model • Belgium (Flanders) Vlier-Humaan • Denmark JAGG • Finland No model • France No model • Germany UMS ; SISIM • Greece No model • Ireland No model • Italy Guiditta; ROME • Luxembourg No model • Netherlands HESP; SUS; Risc-Human • Norway SFT 99:06

  9. Countries and Models (2) • Portugal No model • Spain LUR (Basque Country) • Sweden Report 4639 • Switzerland No model • UK Consim; RAM; P20 ; CLEA • Commercial RISC ; RBCA Toolkit

  10. Selected Models • Belgium Vlier-Humaan • Denmark JAGG • Germany UMS • Italy ROME • Netherlands Risc-Human • Norway SFT 99:06 • UK P20 and CLEA • Commercial RISC and RBCA Toolkit

  11. Test Cases • Lube plant with chlorinated plume • Will show predicted vs. actual GW conc. • Manufactured gas plant with PAHs in soil • Will show soil ingestion results vs. generic site • Fly ash landfill with heavy metals • Chemical plant with chlorinates & pesticides in soil • Petrol filling station with BTEX & MTBE • Will show predicted vs. actual indoor air conc.

  12. Soil Ingestion – Generic vs. Test Case Relative Doses: BaP Soil Ingestion 750

  13. Predicted vs. Actual Indoor Air Vapour Concentrations (ug/m3) in closed forecourt shop

  14. Test Site Conclusions • Using model defaults (vs. generic case) can lead to large differences, even for soil ingestion • Indoor air models with J&E algorithm closely match real BTEX data for specific test case

  15. Risk Assessment Process: conceptual model Human risk Humanrisk Source Pathway Receptor Ecological risk Ecological risk Spreading risk • Chemicals • Concentrations • Toxicity • Exposure Transport in groundwater

  16. Ecological risks • Surface water to groundwater • Effects on ecology (plant, microorganisms,…) Limited specific models available to evaluate ecological risks Ecotoxicity tests available

  17. Spreading risks • Spreading of contamination in groundwater can result in human or ecological risks “Secundary human or ecological risk due to spreading of contaminated groundwater” • Soil- groundwater interactions: Leaching to groundwater

  18. Spreading risks: comparative study Assignment BIM • UK, Flanders, France, Netherlands • Criteria for use of groundwatermodels • Criteria of spreading risks

  19. Criteria for the evaluation of spreading risks • Main issues: • velocity of groundwater contamination (Fl, UK, F, N) • receptors in the surrounding area (e.g.: groundwater wells, drinking water, surface water…) (Fl, UK, F, N) • risks for humans (Fl, UK) • risks of vertical spreading (deeper aquifer) (Fl, F) • use of area and surrouding areas (eg. nature reserve) (Fl, F, N) • presence of pure produkt: continuous source of groundwatercontamination (Fl, F, UK, N) • spreading over different parcels (UK, F, N)

  20. Criteria for the evaluation of spreading risks • Netherlands: specific criteria • 100 m³ /year above intervention value

  21. Criteria for use of groundwatermodels • Large project area • Well known hydrogeology of the site and surrounding areas: geology, grondwater levels,… • Well known data • to controll the model, • to define limiting conditions, • to build op conceptual site model

  22. Overall Conclusions • Consistent defensible results possible where fate & transport / chemical / exposure parameters well understood • Where model defaults are used, significant differences (3 orders magnitude) can occur • Test sites indicate some human risk models are conservative, but others more predictive • Limited specific ecological models exists and/or are validated • Use of groundwatermodels is only recommended for large project areas with sufficient data

  23. Overall Conclusions (2) Risk managers need to critically assess model assumptions & how software applied

  24. Soil Ingestion (Generic Site) Cadmium Relative Dose (normalised to Vlier-Humaan)

  25. Soil Ingestion Models • All models have essentially the same soil ingestion algorithms • In Vlier-Humaan, soil ingestion rates are fixed at relatively low values • CLEA uses hard-wired probabilistic exposure at 95% level exposure 4x higher than most models

  26. Dermal Contact (Generic Site) BaP Relative Dose (normalised to Risc-Human)

  27. Dermal Contact Models • CLEA has smaller dose as contaminant is allowed to volatilise as well as absorb • Vlier- & Risc-Human limits exposure to 2 hrs/day reflecting skin permeability (generic site has a daily ‘event’ with no time effect) • Risc-Human is very low because its soil-on-skin adherence is fixed 10x lower than that in other models

  28. Vegetable Ingestion Relative Doses Normalised to RISC

  29. Vegetable Models • RISC is low because it uses a 1% US EPA adjustment factor on root uptake • CLEA is low but reasons not entirely clear • Six vegetable types and probabilistic dose dissimilar to other models & generic case • UMS fixes root:leaf ingestion at 85% leaf (vs. 50/50 in generic case). Leaf ingestion has higher uptake for lower Koc substances (e.g. benzene)

  30. Soil to Indoor Air Benzene concentrations in mg/m3 46 0.07 Note: UMS concentration is 650x higher than RBCA

  31. Flow thru cracks Flow thru concrete pores Concrete weathering Indoor air 1% of soil gas User input for soil gas intrusion RISC & RBCA Toolkit Vlier- & Risc-Humaan JAGG UMS SFT 99:06 Indoor Air – Soil Algorithms

  32. Generic Site Conclusions • Soil ingestion and groundwater migration models are all similar (one order magnitude) • Vegetable ingestion model results surprisingly uniform (one order magnitude) • Dermal contact models more variable (two orders magnitude) • Indoor air models, particularly UMS code, have highest variability (3 orders magnitude) • Differences attributed to identifiable fixed parameters or algorithms (indoor air)

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