Cytotoxicity assessment of HDPE microplastic on Tetrahymena thermophila (Protozoa, Ciliate): Assuring quality and FAIR data

Microplastics is recognized as an emerging pollutant and adapting and harmonizing existing test methods is essential to advancing research. The aim of our work was to provide a case study on how to ensure quality and FAIR data in the assessment of microplastic hazards with the unicellular organism Tetrahymena thermophila (Protozoa, Ciliata). We selected high density polyethylene (HDPE) microplastics as a model material. In the study design we followed the quality criteria recommended for studies on particle effects, specifically emphasizing the reporting of experimental design and data. Our experimental work was based on ISO 4988 (2022) multigeneration tests with T. thermophila that was upgraded with additional cytotoxicity tests (protocols have been made available on Zenodo). In addition, we used microscopy to inspect material-organism interaction. The results show that 24 h exposure of T. thermophila to HDPE microparticles did not induce changes in metabolic activity, viability, or proliferation up to exposure concentration 100 mg/L. Microscopy analyses confirmed ingestion of the test material but no adsorption of HDPE particles to the cell surfaces confirming that HDPE microplastics present a low hazard to T. thermophila. To maximize the impact of the generated data, we made all the produced data FAIR via the eNanoMapper repository.