Effects of cerium oxide nanoparticles to fish and mammalian cell lines: An assessment of cytotoxicity and methodology

► Cytotoxicity of two nano sized CeO2 particles and a micron sized CeO2 particle. ► A mammalian cell line more sensitive than a fish cell line to CeO2 particle exposure. ► The different assays showed different sensitivity towards nanoparticle exposure. ► Measurement of real concentration is essential to avoid false data interpretation.