Grouping of nanomaterials to read-across hazard endpoints: from data collection to assessment of the grouping hypothesis by application of chemoinformatic techniques

An increasing number of manufactured nanomaterials (NMs) are being used in industrial products and need to be registered under the REACH legislation. The hazard characterisation of all these forms is not only technically challenging but resource and time demanding. The use of non-testing strategies like read-across is deemed essential to assure the assessment of all NMs in due time and at lower cost. The fact that read-across is based on the structural similarity of substances represents an additional difficulty for NMs as in general their structure is not unequivocally defined. In such a scenario, the identification of physicochemical properties affecting the hazard potential of NMs is crucial to define a grouping hypothesis and predict the toxicological hazards of similar NMs. In order to promote the read-across of NMs, ECHA has recently published “Recommendations for nanomaterials applicable to the guidance on QSARs and Grouping”, but no practical examples were provided in the document. Due to the lack of publicly available data and the inherent difficulties of reading-across NMs, only a few examples of read-across of NMs can be found in the literature. This manuscript presents the first case study of the practical process of grouping and read-across of NMs following the workflow proposed by ECHA. The workflow proposed by ECHA was used and slightly modified to present the read-across case study. The Read-Across Assessment Framework (RAAF) was used to evaluate the uncertainties of a read-across within NMs. Chemoinformatic techniques were used to support the grouping hypothesis and identify key physicochemical properties. A dataset of 6 nanoforms of TiO2 with more than 100 physicochemical properties each was collected. In vitro comet assay result was selected as the endpoint to read-across due to data availability. A correlation between the presence of coating or large amounts of impurities and negative comet assay results was observed. The workflow proposed by ECHA to read-across NMs was applied successfully. Chemoinformatic techniques were shown to provide key evidence for the assessment of the grouping hypothesis and the definition of similar NMs. The RAAF was found to be applicable to NMs

In vitro evaluation of SiC nanoparticles impact on A549 pulmonary cells: Cyto-, genotoxicity and oxidative stress

International audienceSilicon carbide (SiC) is considered a highly biocompatible material, consequently SiC nanoparticles (NPs) have been proposed for potential applications in diverse areas of technology. Since no toxicological data are available for these NPs, the aim of this study was to draw their global toxicological profile on A549 lung epithelial cells, using a battery of classical in vitro assays. Five SiC-NPs, with varying diameters and Si/C ratios were used, and we show that these SiC-NPs are internalized in cells where they cause a significant, though limited, cytotoxic effect. Cell redox status is deeply disturbed: SiC-NP exposure cause reactive oxygen species production, glutathione depletion and inactivation of some antioxidant enzymes: glutathione reductase, superoxide dismutase, but not catalase. Finally, the alkaline comet assay shows that SiC-NPs are genotoxic. Taken together, these data prove that SiC-NPs biocompatibility should be revisited

Cytotoxic and Genotoxic Impact of TiO2 Nanoparticles on A549 Cells

International audienceTitania nanoparticles are produced by tons, and included in commercial products, raising concerns about their potential impact on human health. This study relates their cytotoxic and genotoxic impact on a cell line representative of human lung, namely A549 alveolar epithelial cells

Titanium dioxide nanoparticles exhibit genotoxicity and impair DNA repair activity in A549 cells

International audienceTitanium dioxide nanoparticles (TiO2-NPs) are produced in large quantities, raising concerns about their impact for human health. The aim of this study was to deeply characterize TiO2-NPs genotoxic potential to lung cells, and to link genotoxicity to physicochemical characteristics, e.g., size, specific surface area, crystalline phase. A549 cells were exposed to a panel of TiO2-NPs with diameters ranging from 12 to 140 nm, either anatase or rutile. A set of complementary techniques (comet and micronucleus assays, gamma-H2AX immunostaining, 8-oxoGuanine analysis, H2-DCFDA, glutathione content, antioxidant enzymes activities) allowed us to demonstrate that small and spherical TiO2-NPs, both anatase and rutile, induce single-strand breaks and oxidative lesions to DNA, together with a general oxidative stress. Additionally we show that these NPs impair cell ability to repair DNA, by inactivation of both NER and BER pathways. This study thus confirms the genotoxic potential of TiO2-NPs, which may preclude their mutagenicity and carcinogenicity

Mechanisms of TiO2 nanoparticles genotoxicity: impact on DNA repair in, A549 and BEAS-2B Epithelial Pulmonary Cells

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Investigation of TiO2 nanoparticles translocation through a Caco-2 monolayer

International audienceNanoparticles (NPs) are introduced in a growing number of commercial products, including food and beverage but their effects on gastrointestinal tract are poorly investigated. Here we focused on the translocation of TiO2 NPs through Caco-2 monolayers exposed to anatase and rutile NPs up to 24 h. Internalization was followed by transmission electronic microscopy and μ-XRF elemental mapping, coupled to XAS analysis of Ti atoms environment. This innovative technique is among the best techniques to get insights on NP fate after internalization. The originality of this project relies on the panel of microscopy techniques implemented to investigate digestive barrier translocation, bringing together biologists, chemists and physicists in a pluridisciplinary research program

SiC nanoparticles cyto- and genotoxicity to Hep-G2 cells

International audienceWhile emerging nanotechnologies have seen significant development in recent years, knowledge on exposure levels as well as data on toxicity of nanoparticles are still quite limited. Indeed, there is a general agreement that development of nanotechnologies may lead to considerable dissemination of nanoparticles in the environment. Nevertheless, questions relative to toxicity versus innocuousness of such materials still remain. Our present study has thus been carried out with the purpose of assessing some aspects of toxicological capacities of three kinds of nano-sized particles: TiO2 and SiC nanoparticles, as well as multi-walled carbon nanotubes (CNT). In order to address the question of their potential toxicity toward living cells, we chose several cellular models. Assuming inhalation as the most probable exposure scenario, we used A549 alveolar epithelial cells as a model for mammalian primary target organ (lung). Furthermore, we considered that nanoparticles that would deposit into the pulmonary system may be translocated to the circulatory system. Thus, we decided to study the effect of nanoparticles on potentially secondary target organs: liver (WIF-B9, Can-10, HepG2) and kidneys (NRK-52E, LLC-PK1). Herein, we will focus our attention on results obtained on the HepG2 cell line exposed to SiC nanoparticles. Scarce literature exists on SiC nanotoxicology. According to the authors that have already carried out studies on this particular nanoparticle, it would seem that SiC nanoparticles do not induce cytotoxicity. That is one of the reasons of the potential use of these nanoparticles as biological labels [1]. We thus were interested in acquiring more data on biological effects induced by SiC nanoparticles. Furthermore, one of the particular aspects of the present study lies in the fact that we tried to specify the influence of physico-chemical characteristics of nanoparticles on toxicological endpoints (cytotoxicity and genotoxicity)