Cytotoxic effects of commonly used nanomaterials and microplastics on cerebral and epithelial human cells

Plastic wastes are among the major inputs of detritus into aquatic ecosystems. Also, during recent years the increasing use of new materials such as nanomaterials (NMs) in industrial and household applications has contributed to the complexity of waste mixtures in aquatic systems. The current effects and the synergism and antagonisms of mixtures of microplastics (MPLs), NMs and organic compounds on the environment and in human health have, to date, not been well understood but instead they are a cause for general concern. The aim of this work is to contribute to a better understanding of the cytotoxicity of NMs and microplastics/nanoplastics (MPLs/NPLs), at cell level in terms of oxidative stress (evaluating Reactive Oxygen Species effect) and cell viability. Firstly, the individual cytotoxicity of metal nanoparticles (NPs) (AgNPs and AuNPs), of metal oxide NPs (ZrO₂NPs, CeO₂NPs, TiO₂NPs, and Al₂O₃NPs), carbon nanomaterials (C₆₀fullerene, graphene), and MPLs of polyethylene (PE) and polystyrene (PS) has been evaluated in vitro. Two different cellular lines T98G and HeLa, cerebral and epithelial human cells, respectively, were employed. The cells were exposed during 24-48h to different levels of contaminants, from 10ng/mL to 10µg/mL, under the same conditions. Secondly, the synergistic and antagonistic relationships between fullerenes and other organic contaminants, including an organophosphate insecticide (malathion), a surfactant (sodium dodecylbenzenesulfonate) and a plasticiser (diethyl phthalate) were assessed. The obtained results confirm that oxidative stress is one of the mechanisms of cytotoxicity at cell level, as has been observed for both cell lines and contributes to the current knowledge of the effects of NMs and MPLs-NPLs.