Paul van den Brink (chair), Wageningen University; Elke Zimmer (co-chair), ibacon GmbH; Georg Streck (co-chair), European Commission; Thomas Preuss, Bayer AG; Udo Hommen, Fraunhofer IME; Simon Gutierrez Alonso, European Chemicals Agency; Anna-Maija Nyman, European Chemicals Agency; Jose Tarazona, European Food Safety Authority; and Véronique Poulsen, L’Oréal, SETAC Special Science Symposium Steering Committee

The SETAC Europe 13th Special Science Symposium (SESSS), titled “Extrapolation of Effects Across Biological Levels: Challenges to Implement Scientific Approaches in Regulation,” will be held from 23–24 October 2018 at the Marivaux Hotel in, Brussels, Belgium.

As recognized by the European horizon scanning project paper recently published in ET&C, one of the biggest challenges in the ecological risk assessment of chemicals, such as pesticides, pharmaceuticals, industrial chemicals, personal and home care products and biocides, is to extrapolate effects of chemicals across different levels of biological organization. For example, we measure the survival of water fleas in the laboratory, but we want to protect aquatic invertebrate populations in the field. In most cases, extrapolation is assumed to be covered using assessment factors applied to the results of single species toxicity tests, typically at the organism level. Nevertheless, there is uncertainty on whether this extrapolation is protective enough or overprotective. Extrapolation itself is always a model-driven exercise.

In higher-tier risk assessment of some chemicals like pesticides and biocides, experimental approaches are available to address the higher levels of biological organization, such as population studies at the laboratory, field or community level (aquatic micro or mesocosm studies or field studies on soil invertebrates). However, due to their higher complexity, their use in risk assessment is often a matter of debate and such experiments cannot cover the diversity of potential situations in the field.

On one hand, chemical legislations such as REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) and the Biocidal Product Regulation have a high need for standard toxicity testing, but at the same time they promote the use of non-animal alternative methods to create the data that underpin the legislation to reduce testing on vertebrate animals. For this purpose, prediction of toxicity across substances is recognized as a potential tool. Alternatively, prediction of the effects on organisms may be done based on sub-individual, in vitro, (cell-based) assays or biomarkers and extrapolating the effects to the organism level. Although significant progress has been made with respect to modeling approaches, their actual incorporation of these modeling approaches into the regulatory risk assessment has been very limited.

As of now, mechanistic models to extrapolate from lower to higher levels of biological organization have been rarely applied in regulatory risk assessments, such as the assessment of bioconcentration or magnification or dietary exposure in the risk assessment for birds and mammals.

New developments that facilitate the extrapolation of effects observed in experiments amongst different levels of biological organization include the development of quantitative adverse outcome pathways (AOPs), toxicokinetic-toxicodynamic (TK-TD) modeling (link exposure to the organism level), population models (organism to population level), ecosystem and food chain models (population to community or ecosystem level), and landscape-level models (explicit consideration of spatial heterogeneity in population or ecosystem models). In general, these models can be linked with each other to extrapolate the effects of chemicals from the sub-organism level to the ecosystem level and can use experimental data to parameterize the extrapolations or validate them. One of the biggest advantages of such modeling approaches is that they can not only extrapolate but also integrate. For example, lethal and sublethal effects at the population level can be interactively analysed, and by linking such modelling to landscape-scaled models, multiple stressors can be evaluated for different environmental scenarios. Such analyses could help to bring answers to some of today’s big questions in ecological risk assessment, such as questions related to the propagation of sub-lethal effects to the population level, effects at landscape scales, multiple stressors and ecological interactions. A key element for data-rich substances is to discuss how all available information can be integrated in realistic higher-level assessments, e.g., addressing the expected impacts on ecosystem services.

During this SETAC Europe 13th Special Science Symposium (SESSS), we will start with the regulatory views of the European Food Safety Authority(EFSA), European Commission (EC) and European Chemicals Agency (ECHA) covering current practices, outlook and challenges for the implementation of new developments into the risk assessment schemes of the different chemical regulations. This will be followed by presentations by experts on novel experimental and modelling approaches, as well as successful case study presentations on how these approaches could inform future risk assessments of chemicals in the regulatory context. A full program can be obtained from the website.

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