From polymer to commercial product: Unravelling the ecotoxicological effects of PVA-based dishwasher pods

Water-soluble polymers (WSPs) are emerging as a largely overlooked class of contaminants. Despite their widespread use, the lack of specific regulation contributes to the uncontrolled release, especially into aquatic ecosystems, raising concerns for environmental and human health. Among WSP-based consumer products, dishwasher pods are widely used and are typically enclosed in a water-soluble film made of polyvinyl alcohol (PVA) and formulation additives. This study provided an integrated ecotoxicological assessment of such films in zebrafish (Danio rerio), combining physicochemical characterization and multitier approach spanning molecular to organismal levels, including metabolomics, oxidative stress and neurotoxicity biomarkers, energetic metabolism, cardiac activity, morphology, and behaviour. PVA was first separated from additives, and the resulting fractions were chemically characterized. Embryos were then exposed to the whole film (0.1 mg/L), reflecting environmentally-relevant concentrations, and the corresponding concentrations of PVA (0.07 mg/L) and additives (0.03 mg/L). Chemical analyses indicated that the film consisted of 70% PVA and 30% additives, mainly polyhydric alcohols and polyethylene glycol oligomers. Exposures induced subtle yet biologically meaningful alterations across all levels of the biological organization: PVA selectively affected mitochondrial respiration and eye development, while additives and pod film induced broader metabolic reprogramming, neurotoxicity, and decreased tail-coiling activity. Additives also induced significant bradycardia and increased body length. Notably, these findings revealed a substantial contribution of additives to the observed toxicity patterns, despite being present at lower concentrations. Overall, pod film toxicity could not be predicted from individual components, indicating mixture-specific effects and challenging the assumption that PVA-based products are environmentally safe, highlighting the need to assess commercial formulations as complex mixtures.