To Örebro University

Lithium demand is increasing due to its widespread use in rechargeable batteries, raising concerns about its release into aquatic environments. The bioavailability and toxicity of lithium under aquatic test conditions can be influenced by water chemistry and experimental conditions such as pH and exposure vessel material. This study investigated effects of plate material and pH on lithium concentrations and developmental, teratogenic, and behavioural responses in zebrafish embryos based on the OECD Test Guideline 236 - Fish Embryo Toxicity Test. Experiments were conducted in polystyrene and polypropylene plates under unmodified (pH 7.6) and acidified conditions (pH 6). Additionally, lithium speciation modelling was performed to evaluate potential changes in chemical speciation. No developmental and teratogenic changes were observed in exposed larvae. However, at higher target concentrations, measured lithium recoveries were higher in polypropylene plates, which was potentially attributed to higher inertness of polypropylene surfaces. Gene expression analysis further revealed material-dependent molecular responses, suggesting biological responses at the transcriptional level at low concentrations. Behavioural analyses showed reduced locomotor response at higher lithium concentrations, with stronger effects at pH 6. Speciation modelling demonstrated that lithium species distribution predominantly remained the same under all tested conditions, indicating that pH-related effects were unlikely driven by changes in lithium speciation. Protein-like compounds were formed under all experimental conditions, independent of plate material and pH, hinting towards in situ production and a limited role in binding large lithium fractions. Overall, our results show that experimental material and pH influence toxicity test outcomes and should therefore be carefully considered when designing aquatic toxicity tests.

This study investigated the amount and proportion of unidentified organofluorine (UOF) in human serum and assessed short-term variability in exposure using extractable organofluorine (EOF) analysis and a fluorine mass balance approach. Serum samples were obtained from the well-characterized EuroMix cohort, comprising residents living in and around Oslo, Norway, collected between September 2016 and November 2017. Short-term intra-individual variability was evaluated using 72 paired serum samples collected 2-3 weeks apart. An extended target list of 64 PFAS, including trifluoroacetic acid (TFA), was applied to quantify identified and unidentified EOF. UOF accounted for up to 81% of EOF (median: 38%) in EuroMix samples. In 36% of paired samples, EOF concentrations varied by more than 25% over the 2-3-week interval, indicating the presence of compounds with relatively short biological half-lives. TFA was the most abundant individual PFAS detected, with median concentrations approximately twice those of PFOS. In a separate case study, serum samples from individuals using the fluorinated pharmaceutical Fluoxetine showed substantially elevated EOF and TFA concentrations (EOF: median 140 ng F/mL; TFA: median 27.7 ng/mL) compared with samples from individuals not using Fluoxetine (EOF: median < 8 ng F/mL; TFA: median 6.22 ng/mL). These findings indicate that fluorinated pharmaceuticals may contribute significantly to circulating EOF and TFA in humans. The large fraction of UOF and the widespread occurrence of TFA highlight the need to identify their sources relevant to human exposure. Together, these findings indicate that current PFAS including TFA biomonitoring approaches capture only a fraction (estimated to be 50%) of total human exposure to fluorinated substances and highlight the need to complement target analysis with fluorine mass balance approaches in future exposure assessment.

Climate change is driving extreme weather patterns, leading to prolonged droughts and more frequent intense precipitation events. These environmental changes will impact aquatic systems by altering essential water quality parameters such as temperature, redox potential, pH, suspended solids and organic matter, which influence pollutant solubility and determine ecosystem health as well as drinking water production. In this context, sediments play a crucial role as they represent both a sink and source of pollutants. Therefore, sediment toxicity testing is essential for accurate environmental risk assessments. However, there remains a gap regarding comprehensive sediment testing ap-proaches that integrate multiple biomarker responses.

The SEASON project uses an interdisciplinary approach combining strategies of environmental toxicology, analytical chemistry, andhydro geochemistry. The aim is to develop conceptual models for evaluating, understanding and predicting the impact of climate change effects on the fate, bioavailability, and toxicity of pollutants in the aquatic environment. This project focuses on risks associated with sediments contaminated by organic and inorganic pollutants, specifically metals and PFAS (per- and polyfluoroalkyl substances). By studying factors such as temperature, pH, microbial communities, and sediment-water interactions, the project seeks to understand how different climate change aspects affect pollutant behavior in aquatic ecosystems.

The project consists of four sub-projects. Three investigate different chemical groups and mixtures under varying water conditions, using zebrafish (Danio rerio) as the main model organism. These studies will include in vitro and in vivo assays, microcosm experiments, microbiome studies and chemical analyses. The fourth subproject will integrate the results to develop a predictive model for sediment risk assessment.

Sediment contact assays will be performed to evaluate the effects of contaminated samples on zebrafish embryos by measuring teratogenicity, developmental toxicity, behavioral changes, and gene expression. In microcosm studies, we will vary pH and mimic increased precipitation events to assess pollutant toxicity in adult zebrafish including sex-related toxicity differences, reproduction, and behavior. Effect-directed analysis (EDA) will be used to identify key toxicants in the samples. Microbiome analysis using metagenomic sequencing will focus on how contaminated sediments alter bacterial communities, which in turn can affect pollutant distribution and bioavailability. Chemical analyses will quantify PFAS, metals, and their speciation throughout the study. Ultimately, the project will integrate these data to develop models that increase our understanding of the impact of climate change on sediment contamination and aquatic ecosystem health.