| Summary: | When materials are produced at the nanoscale range, their surface chemistry changes, chemical reactivity increases and other important material properties may be altered, including optical, magnetic and electrical properties. Nanomaterials (NMs) display advantageous characteristics that enable innovative applications, as is the case of several metal and metal oxides such as titanium dioxide nanomaterials (TiO2), cerium dioxide (CeO2) and barium sulphate (BaSO4), that already have a broad range of applications in industry and consumer products. However, the exponential development of nanotechnologies contrasts with the insufficient risk assessment for human health and the environment and reliable studies focused on nano-bio interactions are necessary1. With the aim of contributing to a comprehensive investigation of the hazard of metal oxides NMs in human respiratory cells, we have used cytotoxicity and genotoxicity assays2, concomitantly with the analysis of the NMs’ properties in the cellular moiety. The results show that only CeO2 has cytotoxic effects and TiO2 is genotoxic in the comet assay, but not clastogenic in the micronucleus assay. The remaining NMs are not genotoxic. The present results contribute to evaluate the hazard of the tested NMs, suggesting that some, but not all, metal NMs affect human respiratory cells. Considering the reports describing workers occupationally exposed to TiO23, this finding raises concerns for human health. Further studies are described that were designed to understand if this finding could be generalized to other TiO2 that are frequently used in consumer products. For tackling NMs’ uncertainties, an in-depth investigation of the nano-bio interactions must be foreseen, where correlation analysis with the primary and secondary physicochemical characteristics may enable grouping strategies valuable for risk assessment.
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