Selecting mechanistic effect models for environmental risk assessment Tjalling Jager SETAC Nantes, April 2016

Contents  Role of models in ERA  Issues in selecting useful effects models  Take home messages exposure assessment risk effects assessment

concentrations, time and space Exposure assessment mechanistic fate model mechanistic fate model theory environment phys-chem properties release scenario

Effects assessment statistics ‘safe’ concentration toxicity test arbitrary factors Standardised: exposure time test conditions species/endpoint constant exposure

Risk assessment? mechanistic fate model mechanistic fate model statistics & safety factors statistics & safety factors

predicted ‘impacts’ over time (and space) mechanistic fate model mechanistic fate model New paradigm for ERA model parameters mechanistic effect model(s) mechanistic effect model(s) environment model parameters see Jager (in press) dedicated testing release scenario

Which effects model(s)? Huge range of models available … (e.g., Galic et al, 2010, Schmolke et al, 2010)  Models differ in: –level of organisation –complexity –generality –‘quality’ (e.g., GMP) –underlying assumptions –…–… Don’t look at models in isolation!

Models in their context protection goals effect models test protocols defined by regulators, too vague … developed by modellers, not tailored to ERA … developed by experimenters, not tailored to model needs … options constraints

Daphnia magna and dichloroaniline individualpopulationecosystem TKTD modelse.g., IBMse.g., AQUATOX intrinsic rate protection goals effect models test protocols options constraints

 DEBtox (e.g., Jager & Zimmer, 2012) individualpopulationecosystem TKTD modelse.g., IBMse.g., AQUATOXintrinsic rate

 DEBtox, MoA: direct effect on repro –NEC = 6.4 µg/L ( ) individualpopulationecosystem TKTD modelse.g., IBMse.g., AQUATOXintrinsic rate Data from Klüttgen & Ratte (1994) protection goals test protocols

protection goals  Exponential growth under constant conditions concentration DCA (µg/L) intrinsic rate (d -1 ) individualpopulationecosystem TKTD modelse.g., IBMse.g., AQUATOXintrinsic rate food 100% food 90% food 80% test protocols

 Martin et al (2013), DEB combined with IBM individualpopulationecosystem TKTD modelse.g., IBMse.g., AQUATOXintrinsic rate Data from Sokull-Klüttgen (1998)

 Population predictions (DEB-IBM) –lab conditions, semi-batch feeding Data from Preuss et al (2010) time (d) abundance control40 µg/L individualpopulationecosystem TKTD modelse.g., IBMse.g., AQUATOXintrinsic rate protection goals test protocols

Semi-batch fed Daphnia in isolation … nutrients individualpopulationecosystem TKTD modelse.g., IBMse.g., AQUATOXintrinsic rate protection goals test protocols

Semi-batch fed Daphnia in isolation …  Add parasites, disease, migration, spatial aspects … nutrients individualpopulationecosystem TKTD modelse.g., IBMse.g., AQUATOXintrinsic rate protection goals test protocols

Summarising individualpopulationecosystem TKTD modelse.g., IBMse.g., AQUATOX intrinsic rate ecological realism, specificity, complexity …

individualpopulationecosystem TKTD modelse.g., IBMse.g., AQUATOX intrinsic rate toxicity testing Summarising data needs, potential model integration … ecological data

individualpopulationecosystem TKTD modelse.g., IBMse.g., AQUATOX intrinsic rate toxicity testing testing recovery Summarising ecological data landscape and mobility options for recovery… intrinsic rate

Take home 1 Science-based ERA requires effect models  Preferably in all tiers (just like fate models)  Set of standard models or sub-models –e.g., Hommen et al, 2015; Grimm & Berger, 2016

Take home 2 Model selection cannot be viewed in isolation  Closely tied to protection goals and test protocols –what exactly do we want to protect? –adjust test protocols to match model needs  Model ‘quality’ and ‘realism’ is not all … –link to protection goal –well-established principles –transparency –…–…

Take home 3 ERA needs more ambitious road map for the future  More structured dialogue between stakeholders … Ecotoxicology needs focus on theory and modelling  In science and education …

More information: on DEBtox/GUTS: summercourse dynamic modelling of toxic effects, 9-17 August 2016 (DK) (register before 1 June!) Relevant new project: “Critical evaluation of effect models for risk assessment of plant protection products” (UBA, UFOPLAN )