Integrated risk assessment: from exposure through AOPs to ecosystem services

Chemical pollution exerts significant and far-reaching effects on biodiversity and the health of ecosystems. Over time, global product and technology consumption has increased the presence of human-made chemicals in the natural environment. Many of these chemicals persist in the environment and become pervasive over time, negatively affecting aquatic ecosystems globally. Aquatic ecosystems provide essential ecosystem services that benefit human society, such as the provision of food. Thus, to understand the link between chemical emissions from product and technology life cycles and their damage on ecosystem health, it is crucial to characterize damage on aquatic ecosystems associated with chemical emissions in life cycle assessment (relevant for product life cycle performance) and ecological risk assessment (relevant for water and ecosystem protection). This is pivotal in facilitating a worldwide shift towards a more sustainable application of chemicals across products and technologies and safeguarding the diversity of aquatic life.

The work presented in this PhD thesis addresses the link of the life cycle of chemical emissions to damage on aquatic ecosystem health by focusing on four research objectives: (i) to develop a consistent framework to link ecotoxicological effects on aquatic organisms to damage on species diversity, functional diversity, and ecosystem services that are fully in line with the boundary conditions of LCIA, (ii) to develop a systematic ecotoxicity test data curation approach to derive a transparent and high-quality dataset of effect test data for more than 10,000 chemicals, (iii) to improve ecotoxicity effects modeling by considering differences in sensitivity of species from different taxonomic groups toward chemical exposure, and (iv) to quantitatively characterize the relationship between mixture-toxicity pressure from chemicals and observed differences in aquatic intra- and inter-species occurrence.

After an introductory chapter, Chapter 2 summarizes possible methods to translate predicted ecotoxicity effects to species and functional diversity loss, culminating damage on ecosystem services damage in life cycle assessment (LCA). Section 1 of this chapter introduces a framework for linking freshwater ecotoxicity impacts to ecosystem services within LCA boundaries. Section 2 discusses approaches for linking ecotoxicity impacts to species loss, functional diversity loss, and ecosystem services damage from an LCA perspective. Section 3 explains the necessary biomonitoring methods for ES assessment, and Section 4 outlines how to link ecotoxicity effects to ecosystem service damage.

Chapter 3 outlines ecotoxicity datasets for different uses, including environmental standards, life cycle assessments, and water quality evaluation. Article II highlights data curation's importance for Articles III and IV. Sections 1 and 2 discuss current data and merging challenges to improve data quality, while Section 3 outlines a curation protocol, and Section 4 presents curated data for Article III and IV analysis.

Chapter 4 introduces splitting Species Sensitivity Distributions (SSDs) based on taxonomic grouping for better model fit and relevance in risk assessment unless data constraints exist. The chapter discusses the current use (Section 1) shortcomings of current SSD usage (Section 2) and introduces a conceptual framework for split SSDs (Section 3). It also covers the role of chemical use and mode of action in SSD derivation (Section 4) and highlights the importance of split SSDs in decision support (Section 5). Additionally, a case study for Life Cycle Assessment input is presented in Section 6.

Chapter 5 provides a stepwise approach to link ecotoxicity impacts with species loss, making it helpful in translating model-predicted species-level effects to damage on biodiversity and ecosystem services in decision-making, like Life Cycle Impact Assessment. The chapter consists of eight sections: Section 1 outlines the fundamental steps to derive the PAF to PDF relationship from monitoring datasets, Section 2 presents chemical concentration data and msPAF(EC10) calculation, Section 3 introduces other abiotic factors that can influence aquatic biodiversity, Section 4 presents species biomonitoring data, Section 5 explores covariation between abiotic pressures including the calculated msPAF, Section 6 discusses trends in species abundance and species richness against msPAF, Section 7 present sensitivity analysis, i.e., a robustness check using a subset of data from one region (water authority) in Netherland, and Section 8 presents the derived PAF to PDF relationship.

The PhD research suggests that the developed damage modeling approach fits well into the LCA framework, offering initial steps to translating ecotoxicity effects to ecosystem services damage. Furthermore, splitting species sensitivity distributions enhances the interpretation of assessment outputs, enabling a quantitative understanding of the link between a mixture toxic pressure and biodiversity loss.

In conclusion, the work conducted in this PhD project contributes to research within the field of life cycle impact assessment and ecological risk assessment by advancing the understanding of the impact of chemical pollution on biodiversity and ecosystem health. It supports environmental protection, LCA, and global freshwater ecosystem management decisions.