Defining Quality Criteria for Nanoplastic Hazard Evaluation: The Case of Polystyrene Nanoplastics and Aquatic Invertebrate Daphnia spp

Polystyrene nanoparticles are the most investigated type of nanoplastics in environmentalhazard studies. It remains unclear whether nanoplastic particles pose a hazard towards aquaticorganisms. Thus, it was our aim to investigate whether the existing studies and data providedtherein are reliable in terms of data completeness. We used the example of Daphnia spp. studies forthe purpose of polystyrene nanoplastic (nanoPS) hazard evaluation. First, a set of quality criteriarecently proposed for nanoplastic ecotoxicity studies was applied. These rather general criteria forall types of nanoplastics and different test organisms were then, in the second step, tailored andrefined specifically for Daphnia spp. and nanoPS. Finally, a scoring system was established by settingmandatory (high importance) as well as desirable (medium importance) criteria and defining athreshold to pass the evaluation. Among the existing studies on nanoPS ecotoxicity for Daphnia spp.(n = 38), only 18% passed the evaluation for usability in hazard evaluation. The few studies thatpassed the evaluation did not allow for conclusions on the hazard potential of nanoPS because therewas no consensus among the studies. The greatest challenge we identified is in data reporting, asonly a few studies presented complete data for hazard evaluation. Supplementary Materials: The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/nano13030536/s1, Figure S1: Share of ecotoxicity data points; Figure S2: Distribution of apical and mechanistic endpoints for potassium dichromate; Table S1: Matrix table; Table S2: Minimum reporting information.