DEBtox Workshop, 2-3 Dec. 2019

1. Harmonised and consistent DEBtox modelling framework, including matching between regulatory questions and specific DEBtox model flavours
2. List of ‘Research experiments’ targeting knowledge gaps, and partners who are interested in doing this research
3. Improved approach for use of DEBtox in a regulatory context: evaluation of DEBtox modelling, place in tiered ERA system, scenarios, use of FOCUS output, sensitivity and uncertainty analysis  
4. Requirements for a protocol for ‘Regulatory experiments’ to parameterise DEBtox related experiments, and partners who will work out and test these protocols

Download the detailed agenda of the meeting.

Background reading materials

1. Challenges related to application of DEBtox modelling in regulatory ERA (Andreas Focks). Download.
   
2. DEBtox background, theory and models (Tjalling Jager). Download.
   
3. ...

Presentations

1. DEBtox flavours and necessary updates for ERA (Tjalling Jager). Download.
2. DEB-TKTD: consistent DEBtox terminology, problem definition & model selection (Neil Sherborne). Download.
   
3. When to use a standard Dynamic Energy Budget model (André Gergs). Download.
   
4. DEB(tox) development project (Benoit Goussen). Download.
   
5. How to deal with inter-individual variability in DEB parameters? First step: sensitivity analysis (Josef Koch). Download.
   
6. ...

Workshop learnings

1. New proposal for nomenclature was made and discussed (DEB-TKTD), manuscript in preparation; a related decision scheme would help choosing which model type to use depending on the risk assessment question.
2. Agreed on approach for the evaluation of FOCUS profiles by using a moving time window. Definition of minimum and maximum  length might be related to the time until onset of effects and the life span of the species, respectively, but needs to be further detailed.
3. Data for Daphnia and Mysid chronic studies allows straight forward application for the calibration given that intermediate measurements are available; while for vertebrate the consequences of fitting DEB-TKTD models to low numbers of observations over time need to be analysed.
4. Recognized potential of DEB-TKTD goes beyond aquatic species and particularly promising for mammals.
5. The application of GUTS TKTD models in Tier 1 would allow a more robust estimation of acute endpoints compared to current approaches. In principle, DEB-TKTD models have the same potential for chronic endpoints.
6.  DEB-TKTD as building block for population models might allow for consistent application for population modelling in regulatory ERA.
7. Agreed that more experimental and in silico case studies are needed to inform further modelling choices.
8. Therefore a follow-up workshop is needed, probably end of 2021.

Way forward

1. Plan and carry out case studies for application of DEB-TKTD modelling for environmental risk assessment.
2. Test different options for applying DEB to FOCUS SW profiles, in particular how to choose which time frame to model.
3. Establish minimum data requirements for a robust DEB-TKTD model calibration (vertebrates).
4. Method development for calculation of confidence and credible intervals and propagation of parameter uncertainty to model output;
5. Development of robust, open source and ideally user-friendly software for the use of DEB-TKT models in ERA.
6. Keeping open communication about pathways to the implementation of mechanistic effect models for the improvement of ERA alive among all stakeholder groups.
7. Ring test of developed software using a set of standard data (real data sets + extreme cases to break the model) and appropriate validation.
8. Ask FOCUS Version Control Group at EFSA to cover also DEB-TKTD models (group has a mandate from European Commission).
9. Determine which processes to be included depending on the risk assessment question; e.g. accounting for extrapolation to variable temperature or food levels.

Upcoming courses and events

• In August 2021, the next summer school "Dynamic modelling of toxic effects" in Denmark is planned. More information on the course page. The course planned for 2020 unfortunately had to be cancelled due to the Covid-19 situation.
• In May 2021, there will be the next run of the DEB school and the DEB symposium. This time, the venue is Halifax, Canada. More information. Note that part of the DEB school will be in tele mode, and there probably will be some way to join the symposium in virtual mode.

Previous events:

• On 3-7 May 2020, at the virtual SETAC, there have been a number of excellent platform and poster presentations dealing with DEBtox. Especially in the session "4.07 – Effect Modelling for Regulatory Environmental Risk Assessment: Current Applications and Future Directions."

Relevant new publications, related to the workshop

• Jager T (2020). Revisiting simplified DEBtox models for analysing ecotoxicity data. Ecol Modell 416:108904. https://doi.org/10.1016/j.ecolmodel.2019.108904
  
• Sherborne N and N Galic (2020). Modelling sublethal effects of chemicals: application of a simplified dynamic energy budget model to standard ecotoxicity data. Environ Sci Technol 54(12):7420-7429. https://doi.org/10.1021/acs.est.0c00140 
  
• Koch J and KAC De Schamphelaere (2020). Estimating inter-individual variability of dynamic energy budget model parameters for the copepod Nitocra spinipes from existing life-history data. Ecol Modell 431:109091. https://doi.org/10.1016/j.ecolmodel.2020.109091 
  
• Sherborne N, N Galic and R Ashauer (2020). Sublethal effect modelling for environmental risk assessment of chemicals: problem definition, model variants, application and challenges. Sci Total Environ 745:141027. https://doi.org/10.1016/j.scitotenv.2020.141027.
  
• ...