European Risk Model Comparison Study Sponsored by NICOLE Wouter Gevaerts, Arcadis Belgium Karen Van Geert, Arcadis Belgium Matt Gardner, Arcadis UK

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

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

DISTRIBUTION SOIL FRACTIONS SOIL AIR CONCENTRATION PORE WATER CONCENTRATION TRANSPORT TO SURFACE SOIL TRANSPORT TO SURFACE WATER TRANSPORT TO GROUNDWATER UPTAKE BY/DEPOSITION ON VEGETATION 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

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

Acknowledgements Sponsors Peer Review Team Consultant Akzo Nobel BNFL BP Fortum ICI JM Bostad 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

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

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

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

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

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.

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

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

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

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

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

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

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

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)

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

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

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

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

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

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

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

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

Vegetable Ingestion Relative Doses Normalised to RISC

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)

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

Indoor Air – Soil Algorithms 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

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)