Staff

Kathrin Fenner

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Prof. Dr. Kathrin Fenner

Senior scientist / group leader

Department Environmental Chemistry

About Me

I am passionate about learning how chemicals degrade in the environment and whether any hazardous transformation products are formed during degradation. The ultimate goal of my research is to develop more accurate methods to assess persistence and risk from transformation product formation in regulatory risk assessment procedures. My research focuses on the following three areas in particular.

  1. Prediction of biodegradation pathways and rates
    Current (Q)SBRs tools to predict biodegradation half-lives produce highly uncertain results and available pathway prediction tools suffer from combinatorial explosion due to a lack of methods to prioritize possible pathways. In my research, I mine biotransformation pathway and rate information to develop novel algorithms for biotransformation prediction. In parallel, my team performs bioreactor experiments with pertinent microbial communities and employ high-resolution mass spectrometry to identify transformation products to use that data to further improve biotransformation prediction
  2. Hazard and risk assessment of transformation products
    The goal of this aspect of my research is to develop models and indicators to predict and assess the environmental fate of transformation products. In collaboration with the team of Prof. B. Escher (UFZ Leipzig, Universität Tübingen) we are developing methods to estimate mixture toxicity of transformation products and their parent compound, using the strong structural resemblance to the parent compounds and what is known about parent toxicity as a guiding principle.
  3. Improved tools for persistence assessment
  4. Persistence assessment is key to all chemical legislations in Europe. In my research, I try to contribute to a critical reflection of current persistence assessment paradigms and methods. For instance, I introduced the concept of joint persistence as novel persistence indicator that accounts for transformation product formation. Currently, I am also working on a project that evaluates the value of the OECD 308 guideline for evaluation of persistence of chemicals at the sediment-water interface.

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Projects

Predicting environment-specific biotransformation of chemical contaminants

PROduCTS - ERC

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In regulatory hazard and risk assessment chemical persistence is assessed through a tiered system of degradation studies.

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Curriculum Vitae

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Publications

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Escher, B. I., Altenburger, R., Blüher, M., Colbourne, J. K., Ebinghaus, R., Fantke, P., … Fenner, K. (2023). Modernizing persistence–bioaccumulation–toxicity (PBT) assessment with high throughput animal-free methods. Archives of Toxicology, 97, 1267-1283. doi:10.1007/s00204-023-03485-5, Institutional Repository

The assessment of persistence (P), bioaccumulation (B), and toxicity (T) of a chemical is a crucial first step at ensuring chemical safety and is a cornerstone of the European Union's chemicals regulation REACH (Registration, Evaluation, Authorization, and Restriction of Chemicals). Existing methods for PBT assessment are overly complex and cumbersome, have produced incorrect conclusions, and rely heavily on animal-intensive testing. We explore how new-approach methodologies (NAMs) can overcome the limitations of current PBT assessment. We propose two innovative hazard indicators, termed cumulative toxicity equivalents (CTE) and persistent toxicity equivalents (PTE). Together they are intended to replace existing PBT indicators and can also accommodate the emerging concept of PMT (where M stands for mobility). The proposed "toxicity equivalents" can be measured with high throughput in vitro bioassays. CTE refers to the toxic effects measured directly in any given sample, including single chemicals, substitution products, or mixtures. PTE is the equivalent measure of cumulative toxicity equivalents measured after simulated environmental degradation of the sample. With an appropriate panel of animal-free or alternative in vitro bioassays, CTE and PTE comprise key environmental and human health hazard indicators. CTE and PTE do not require analytical identification of transformation products and mixture components but instead prompt two key questions: is the chemical or mixture toxic, and is this toxicity persistent or can it be attenuated by environmental degradation? Taken together, the proposed hazard indicators CTE and PTE have the potential to integrate P, B/M and T assessment into one high-throughput experimental workflow that sidesteps the need for analytical measurements and will support the Chemicals Strategy for Sustainability of the European Union.
Satoh, H., Hafner, J., Hutter, J., & Fenner, K. (2023). Can AI help improve water quality? Towards the prediction of degradation of micropollutants in wastewater. Chimia, 77(1-2), 48-55. doi:10.2533/chimia.2023.48, Institutional Repository

Micropollutants have become a serious environmental problem by threatening ecosystems and the quality of drinking water. This account investigates if advanced AI can be used to find solutions for this problem. We review background, the challenges involved, and the current state-of-the-art of quantitative structure–bio-degradation relationships (QSBR). We report on recent progress combining experiment, quantum chemistry (QC) and chemoinformatics, and provide a perspective on potential future uses of AI technology to help improve water quality.
Seller, C., Varga, L., Börgardts, E., Vogler, B., Janssen, E., Singer, H., … Honti, M. (2023). Do biotransformation data from laboratory experiments reflect micropollutant degradation in a large river basin?. Water Research, 235, 119908 (13 pp.). doi:10.1016/j.watres.2023.119908, Institutional Repository

Identifying a chemical's potential for biotransformation in the aquatic environment is crucial to predict its fate and manage its potential hazards. Due to the complexity of natural water bodies, especially river networks, biotransformation is often studied in laboratory experiments, assuming that study outcomes can be extrapolated to compound behavior in the field. Here, we investigated to what extent outcomes of laboratory simulation studies indeed reflect biotransformation kinetics observed in riverine systems. To determine in-field biotransformation, we measured loads of 27 wastewater treatment plant effluent-borne compounds along the Rhine and its major tributaries during two seasons. Up to 21 compounds were detected at each sampling location. Measured compound loads were used in an inverse model framework of the Rhine river basin to derive k'bio,field values – a compound-specific parameter describing the compounds' average biotransformation potential during the field studies. To support model calibration, we performed phototransformation and sorption experiments with all the study compounds, identifying 5 compounds that are susceptible towards direct phototransformation and determining Koc values covering four orders of magnitude. On the laboratory side, we used a similar inverse model framework to derive k'bio,lab values from water-sediment experiments run according to a modified OECD 308-type protocol. The comparison of k'bio,lab and k'bio,field revealed that their absolute values differed, pointing towards faster transformation in the Rhine river basin. Yet, we could demonstrate that relative rankings of biotransformation potential and groups of compounds with low, moderate and high persistence agree reasonably well between laboratory and field outcomes. Overall, our results provide evidence that laboratory-based biotransformation studies using the modified OECD 308 protocol and k'bio values derived thereof bear considerable potential to reflect biotransformation of micropollutants in one of the largest European river basins.
Tian, R., Posselt, M., Fenner, K., & McLachlan, M. S. (2023). Increasing the environmental relevance of biodegradation testing by focusing on initial biodegradation kinetics and employing low-level spiking. Environmental Science and Technology Letters, 10(1), 40-45. doi:10.1021/acs.estlett.2c00811, Institutional Repository

The environmental relevance of standard biodegradation tests such as OECD 309 has been questioned. Challenges include the interpretation of changing degradation kinetics over the 60–90 incubation days and the effects of chemical spiking on the microbial community. To ameliorate these weaknesses, we evaluated a modified OECD 309 test using water and sediment from three Swedish rivers. For each river, we had three treatments (no spiking, 0.5 μg L–1 spiking, and 5 μg L–1 spiking). The dissipation of a mixture of 56–80 spiked chemicals was followed over 14 days. Changes in dissipation kinetics during the incubation were interpreted as a departure of the microbial community from its initial (natural) state. The biodegradation kinetics were first-order throughout the incubation in the no spiking and 0.5 μg L–1 spiking treatments for almost all chemicals, but for the 5 μg L–1 treatment, more chemicals showed changes in kinetics. The rate constants in the no spiking and 0.5 μg L–1 treatments agreed within a factor of 2 for 35 of 37 cases. We conclude that the environmental relevance of OECD 309 is improved by considering only the initial biodegradation phase and that it is not compromised by spiking multiple chemicals at 0.5 μg L–1.
Varga, L., Fenner, K., Singer, H., & Honti, M. (2023). From market to environment - consumption-normalised pharmaceutical emissions in the Rhine catchment. Water Research, 239, 120017 (10 pp.). doi:10.1016/j.watres.2023.120017, Institutional Repository

Direct and indirect threats by organic micropollutants can only be reliably assessed and prevented if the exposure to these chemicals is known, which in turn requires a confident estimate of their emitted amounts into the environment. APIs (Active Pharmaceutical Ingredients) enter surface waters mostly through the sewer system and wastewater treatment plants (WWTPs). However, their effluent fluxes are highly variable and influenced by several different factors that challenge robust emission estimates. Here, we defined a dimensionless, theoretically consumption-independent ‘escape factor’ (kesc) for estimating the amount of APIs (expected to be) present in WWTP effluents. The factor is determined as the proportion of marketed and actually emitted amounts of APIs. A large collection of German and Swiss monitoring datasets were analyzed to calculate stochastic kesc values for 31 APIs, reflecting both the magnitude and uncertainty of consumption-normalised emissions. Escape factors provide an easy-to-use tool for the estimation of average API emissions and expected variability from numerous WWTPs given that consumption data are provided, thereby supporting simulation modeling of the fate of APIs in stream networks or exposure assessments.
Anliker, S., Santiago, S., Fenner, K., & Singer, H. (2022). Large-scale assessment of organic contaminant emissions from chemical and pharmaceutical manufacturing into Swiss surface waters. Water Research, 215, 118221 (10 pp.). doi:10.1016/j.watres.2022.118221, Institutional Repository

This study presents a nation-wide assessment of the influence of chemical and pharmaceutical manufacturing (CPM) wastewaters on synthetic organic contaminant (SOC) emissions to Swiss surface waters. Geographic Information System (GIS) based analysis of the presence of CPM in wastewater treatment plant (WWTP) catchments revealed wide distribution of this industrial sector across Switzerland, suggesting that one-third of the 718 Swiss WWTPs may be influenced by CPM wastewaters. To reflect the diversity of this type of wastewaters, we investigated the effluents of 11 WWTPs of diverse sizes and technologies, which treated 0-100% wastewater from a variety of CPM activities. In an extensive sampling campaign, we collected temporally high resolved (i.e., daily) samples for 2-3 months to capture the dynamics of CPM discharges. The > 850 samples were then measured with liquid chromatography high-resolution mass spectrometry (LC-HRMS). Non-target characterization of the LC-HRMS time series datasets revealed that CPM wastewaters left a highly variable and site-specific signature in the effluents of the WWTPs. Particularly, compared to WWTPs with purely domestic input, a larger variety of substances (up to 15 times more compounds) with higher maximum concentrations (1-2 orders of magnitude) and more uncommon substances were found in CPM-influenced effluents. Moreover, in the latter, highly fluctuating discharges often contributed to a substantial fraction of the overall emissions. The largely varying characteristics of CPM discharges between different facilities were primarily related to the type of activities at the industries (i.e., production versus processing of chemicals) as well as to the pre-treatment and storage of CPM wastewaters. Eventually, for one WWTP, LC-HRMS time series were correlated with ecotoxicity time series obtained from bioassays and major toxic components could be identified. Overall, in view of their potential relevance to water quality, a strong focus on SOC discharges from CPM is essential, including the design of situation-specific monitoring, as well as risk assessment and mitigation strategies that consider the variability of industrial emissions.
Athanasakoglou, A., & Fenner, K. (2022). Toward characterizing the genetic basis of trace organic contaminant biotransformation in activated sludge: the role of multicopper oxidases as a case study. Environmental Science and Technology, 56(1), 313-324. doi:10.1021/acs.est.1c05803, Institutional Repository

Activated sludge treatment leverages the ability of microbes to uptake and (co)-metabolize chemicals and has shown promise in eliminating trace organic contaminants (TrOCs) during wastewater treatment. However, targeted interventions to optimize the process are limited as the fundamental drivers of the observed reactions remain elusive. In this work, we present a comprehensive workflow for the identification and characterization of key enzymes involved in TrOCs biotransformation pathways in complex microbial communities. To demonstrate the applicability of the workflow, we investigated the role of the enzymatic group of multicopper oxidases (MCOs) as one putatively relevant driver of TrOCs biotransformation. To this end, we analyzed activated sludge metatranscriptomic data and selected, synthesized, and heterologously expressed three phylogenetically distinct MCO-encoding genes expressed in communities with different TrOCs oxidation potentials. Following the purification of the encoded enzymes, we screened their activities against different substrates. We saw that MCOs exhibit significant activities against selected TrOCs in the presence of the mediator compound 2,2'-Azino-bis-3-ethylbenzthiazoline-6-sulfonic acid and, in some cases, also in the presence of the wastewater contaminant 4'-hydroxy-benzotriazole. In the first case, we identified oxidation products previously reported from activated sludge communities and concluded that in the presence of appropriate mediators, bacterial MCOs could contribute to the biological removal of TrOCs. Similar investigations of other key enzyme systems may significantly advance our understanding of TrOCs biodegradation and assist the rational design of biology-based water treatment strategies in the future.
Davenport, R., Curtis-Jackson, P., Dalkmann, P., Davies, J., Fenner, K., Hand, L., … Redman, A. (2022). Scientific concepts and methods for moving persistence assessments into the 21st century. Integrated Environmental Assessment and Management, 18(6), 1454-1487. doi:10.1002/ieam.4575, Institutional Repository

The evaluation of a chemical substance's persistence is key to understanding its environmental fate, exposure concentration, and, ultimately, environmental risk. Traditional biodegradation test methods were developed many years ago for soluble, nonvolatile, single-constituent test substances, which do not represent the wide range of manufactured chemical substances. In addition, the Organisation for Economic Co-operation and Development (OECD) screening and simulation test methods do not fully reflect the environmental conditions into which substances are released and, therefore, estimates of chemical degradation half-lives can be very uncertain and may misrepresent real environmental processes. In this paper, we address the challenges and limitations facing current test methods and the scientific advances that are helping to both understand and provide solutions to them. Some of these advancements include the following: (1) robust methods that provide a deeper understanding of microbial composition, diversity, and abundance to ensure consistency and/or interpret variability between tests; (2) benchmarking tools and reference substances that aid in persistence evaluations through comparison against substances with well-quantified degradation profiles; (3) analytical methods that allow quantification for parent and metabolites at environmentally relevant concentrations, and inform on test substance bioavailability, biochemical pathways, rates of primary versus overall degradation, and rates of metabolite formation and decay; (4) modeling tools that predict the likelihood of microbial biotransformation, as well as biochemical pathways; and (5) modeling approaches that allow for derivation of more generally applicable biotransformation rate constants, by accounting for physical and/or chemical processes and test system design when evaluating test data. We also identify that, while such advancements could improve the certainty and accuracy of persistence assessments, the mechanisms and processes by which they are translated into regulatory practice and development of new OECD test guidelines need improving and accelerating. Where uncertainty remains, holistic weight of evidence approaches may be required to accurately assess the persistence of chemicals.
Desiante, W. L., Carles, L., Wullschleger, S., Joss, A., Stamm, C., & Fenner, K. (2022). Wastewater microorganisms impact the micropollutant biotransformation potential of natural stream biofilms. Water Research, 217, 118413 (13 pp.). doi:10.1016/j.watres.2022.118413, Institutional Repository

Biotransformation is the most important process removing manmade chemicals from the environment, yet mechanisms governing this essential ecosystem function are underexplored. To understand these mechanisms, we conducted experiments in flow-through systems, by colonizing stream biofilms under different conditions of mixing river water with treated (and ultrafiltered) wastewater. We performed biotransformation experiments with those biofilms, using a set of 75 micropollutants, and could disentangle potential mechanisms determining the biotransformation potential of stream biofilms. We showed that the increased biotransformation potential downstream of wastewater treatment plants that we observed for specific micropollutants contained in household wastewaters (downstream effect) is caused by microorganisms released with the treated effluent, rather than by the in-stream exposure to those micropollutants. Complementary data from 16S rRNA amplicon-sequencing revealed 146 amplicon sequence variants (ASVs) that followed the observed biotransformation patterns. Our results align with findings for community tolerance, and provide clear experimental evidence that microorganisms released with treated wastewater integrate into downstream biofilms and impact crucial ecosystem functions.
Riedo, J., Herzog, C., Banerjee, S., Fenner, K., Walder, F., Van Der Heijden, M. G. A., & Bucheli, T. D. (2022). Concerted evaluation of pesticides in soils of extensive grassland sites and organic and conventional vegetable fields facilitates the identification of major input processes. Environmental Science and Technology, 56(19), 13686-13695. doi:10.1021/acs.est.2c02413, Institutional Repository

The intensive use of pesticides and their subsequent distribution to the environment and non-target organisms is of increasing concern. So far, little is known about the occurrence of pesticides in soils of untreated areas- such as ecological refuges- as well as the processes contributing to this unwanted pesticide contamination. In this study, we analyzed the presence and abundance of 46 different pesticides in soils from extensively managed grassland sites, as well as organically and conventionally managed vegetable fields (60 fields in total). Pesticides were found in all soils, including the extensive grassland sites, demonstrating a widespread background contamination of soils with pesticides. The results suggest that after conversion from conventional to organic farming, the organic fields reach pesticide levels as low as those of grassland sites not until 20 years later. Furthermore, the different pesticide composition patterns in grassland sites and organically managed fields facilitated differentiation between long-term persistence of residues and diffuse contamination processes, that is, short-scale redistribution (spray drift) and long-scale dispersion (atmospheric deposition), to offsite contamination.

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Address

E-Mail: kathrin.fenner@eawag.ch
Phone: +41 58 765 5085
Fax: +41 58 765 5802
Address: Eawag
Überlandstrasse 133
8600 Dübendorf
Office: BU F18
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Expert on

biological degradation, mass spectrometry, micropollutants, organic pollutants

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Research Group

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