Review of nanomaterial aging and transformations through the life cycle of nano-enhanced products

International audienceIn the context of assessing potential risks of engineered nanoparticles (ENPs), life cycle thinking can represent a holistic view on the impacts of ENPs through the entire value chain of nano-enhanced products from production, through use, and finally to disposal. Exposure to ENPs in consumer or environmental settings may either be to the original, pristine ENPs, or more likely, to ENPs that have been incorporated into products, released, aged and transformed. Here, key product-use related aging and transformation processes affecting ENPs are reviewed. The focus is on processes resulting in ENP release and on the transformation(s) the released particles undergo in the use and disposal phases of its product life cycle for several nanomaterials (Ag, ZnO, TiO 2 , carbon nanotubes, CeO 2 , SiO 2 etc.). These include photochemical transformations, oxidation and reduction, dissolution, precipitation , adsorption and desorption, combustion, abrasion and biotransformation, among other biogeochemical processes. To date, few studies have tried to establish what changes the ENPs undergo when they are incorporated into, and released from, products. As a result there is major uncertainty as to the state of many ENPs following their release because much of current testing on pristine ENPs may not be fully relevant for risk assessment purposes. The goal of this present review is therefore to use knowledge on the life cycle of nano-products to derive possible transformations common ENPs in nano-products may undergo based on how these products will be used by the consumer and eventually discarded. By determining specific gaps in knowledge of the ENP transformation process, this approach should prove useful in narrowing the number of physical experiments that need to be conducted and illuminate where more focused effort can be placed

Elemental recoveries for metal oxide nanoparticles analysed by direct injection ICP-MS: influence of particle size, agglomeration state and sample matrix

International audienceThe direct analysis of metal-oxide nanoparticles (NPs) in suspension by inductively coupled plasma-mass spectrometry (ICP-MS) has been investigated. The roles of the chemical nature, size, crystalline form and agglomeration state of the particles in the recovery rate - compared with dissolved samples - have been investigated. Various sample matrices have been tested with the aim to optimize the decomposition process of the particles in the plasma, which governs the quality of the ICP-MS analytical results. It was found that, for SiO2 and ZnO, full recovery was readily obtained in 10(-3) mol L-1 NaOH or 0.1% HNO3, respectively. In the case of more stable oxides like TiO2 or CeO2, a positive correlation of the recovery with the concentration of HNO3 in the matrix could be observed, although only NaOH could lead to identical sensitivities for NPs and ionic solutes. Al2O3 could not be satisfactorily analysed (80% recovery at the most). Size and agglomeration state characterization of the selected particles was performed by scanning electron microscopy and dynamic light scattering. The agglomeration state was found to be of minor influence but the size of the primary particle as well as its crystalline phase plays an important role in the analytical recovery

Transport of nanoparticulate TiO2 UV-filters through a saturated sandcolumn at environmentally relevant concentrations

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Strategy for the lowering and the assessment of exposure to nanoparticles at workspace - Case of study concerning the potential emission of nanoparticles of Lead in an epitaxy laboratory

International audienceThe implementation in many products of manufactured nanoparticles is growing fast and raises new questions. For this purpose, the CEA - NanoSafety Platform is developing various research topics for health and safety, environment and nanoparticles exposure in professional activities. The containment optimisation for the exposition lowering, then the exposure assessment to nanoparticles is a strategy for safety improvement at workplace and workspace. The lowering step consists in an optimisation of dynamic and static containment at workplace and/or workspace. Generally, the exposure risk due to the presence of nanoparticles substances does not allow modifying the parameters of containment at workplace and/or workspace. Therefore, gaseous or nanoparticulate tracers are used to evaluate performances of containment. Using a tracer allows to modify safely the parameters of the dynamic containment (ventilation, flow, speed) and to study several configurations of static containment. Moreover, a tracer allows simulating accidental or incidental situation. As a result, a safety procedure can be written more easily in order to manage this type of situation. The step of measurement and characterization of aerosols can therefore be used to assess the exposition at workplace and workspace. The case of study, aim of this paper, concerns the potential emission of Lead nanoparticles at the exhaust of a furnace in an epitaxy laboratory. The use of Helium tracer to evaluate the performance of containment is firstly studied. Secondly, the exposure assessment is characterised in accordance with the French guide "recommendations for characterizing potential emissions and exposure to aerosols released from nanomaterials in workplace operations". Thirdly the aerosols are sampled, on several places, using collection membranes to try to detect traces of Lead in ai

Corrigendum: Assessing Sunscreen Lifecycle to Minimize Environmental Risk Posed by Nanoparticulate UV-Filters – A Review for Safer-by-Design Products

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Silver Accumulation in the Green Microalga Coccomyxa actinabiotis: Toxicity, in Situ Speciation, and Localization Investigated Using Synchrotron XAS, XRD, and TEM.

International audienceMicroalgae are good candidates for toxic metal remediation biotechnologies. This study explores the cellular processes implemented by the green microalga Coccomyxa actinabiotis to take up and cope with silver over the concentration range of 10(-7) to 10(-2) M Ag(+). Understanding these processes enables us to assess the potential of this microalga for applications for bioremediation. Silver in situ speciation and localization were investigated using X-ray absorption spectroscopy, X-ray diffraction, and transmission electron microscopy. Silver toxicity was evaluated by monitoring microalgal growth and photochemical parameters. Different accumulation mechanisms were brought out depending on silver concentration. At low micromolar concentration, microalgae fixed all silver initially present in solution, trapping it inside the cells into the cytosol, mainly as unreduced Ag(I) bound with molecules containing sulfur. Silver was efficiently detoxified. When concentration increased, silver spread throughout the cell and particularly entered the chloroplast, where it damaged the photosystem. Most silver was reduced to Ag(0) and aggregated to form crystalline silver nanoparticles of face-centered cubic structure with a mean size of 10 nm. An additional minor interaction of silver with molecules containing sulfur indicated the concomitant existence of the mechanism observed at low concentration or nanoparticle capping. Nanoparticles were observed in chloroplasts, in mitochondria, on the plasma membrane, on cytosolic membrane structures, and in vacuoles. Above 10(-4) M Ag(+), damages were irreversible, and photosynthesis and growth were definitely inhibited. However, high silver amounts remained confined inside microalgae, showing their potential for the bioremediation of contaminated water

Physicochemical Transformations of Silver Nanoparticles in the Oro-Gastrointestinal Tract Mildly Affect Their Toxicity to Intestinal Cells In Vitro: An AOP-Oriented Testing Approach

International audienceThe widespread use of silver nanoparticles (Ag NPs) in food and consumer products suggests the relevance of human oral exposure to these nanomaterials (NMs) and raises the possibility of adverse effects in the gastrointestinal tract. The aim of this study was to investigate the toxicity of Ag NPs in a human intestinal cell line, either uncoated or coated with polyvinylpyrrolidone (Ag PVP) or hydroxyethylcellulose (Ag HEC) and digested in simulated gastrointestinal fluids. Physicochemical transformations of Ag NPs during the different stages of in vitro digestion were identified prior to toxicity assessment. The strategy for evaluating toxicity was constructed on the basis of adverse outcome pathways (AOPs) showing Ag NPs as stressors. It consisted of assessing Ag NP cytotoxicity, oxidative stress, genotoxicity, perturbation of the cell cycle and apoptosis. Ag NPs caused a concentration-dependent loss of cell viability and increased the intracellular level of reactive oxygen species as well as DNA damage and perturbation of the cell cycle. In vitro digestion of Ag NPs did not significantly modulate their toxicological impact, except for their genotoxicity. Taken together, these results indicate the potential toxicity of ingested Ag NPs, which varied depending on their coating but did not differ from that of non-digested NPs

Physicochemical Transformations of Silver Nanoparticles in the Oro-Gastrointestinal Tract Mildly Affect Their Toxicity to Intestinal Cells In Vitro: An AOP-Oriented Testing Approach

International audienceThe widespread use of silver nanoparticles (Ag NPs) in food and consumer products suggests the relevance of human oral exposure to these nanomaterials (NMs) and raises the possibility of adverse effects in the gastrointestinal tract. The aim of this study was to investigate the toxicity of Ag NPs in a human intestinal cell line, either uncoated or coated with polyvinylpyrrolidone (Ag PVP) or hydroxyethylcellulose (Ag HEC) and digested in simulated gastrointestinal fluids. Physicochemical transformations of Ag NPs during the different stages of in vitro digestion were identified prior to toxicity assessment. The strategy for evaluating toxicity was constructed on the basis of adverse outcome pathways (AOPs) showing Ag NPs as stressors. It consisted of assessing Ag NP cytotoxicity, oxidative stress, genotoxicity, perturbation of the cell cycle and apoptosis. Ag NPs caused a concentration-dependent loss of cell viability and increased the intracellular level of reactive oxygen species as well as DNA damage and perturbation of the cell cycle. In vitro digestion of Ag NPs did not significantly modulate their toxicological impact, except for their genotoxicity. Taken together, these results indicate the potential toxicity of ingested Ag NPs, which varied depending on their coating but did not differ from that of non-digested NPs

Toxicity and chemical transformation of silver nanoparticles in A549 lung cells: dose-rate-dependent genotoxic impact

International audienceSilver nanoparticles (Ag-NPs) are widely used as biocides, leading to contamination of the environment and possible adverse effects on humans. Recent studies revealed that the cellular response to acute exposure to Ag-NPs differs from the response to chronic exposure, although we currently lack systematic studies comparing responses to different dosing regimens. In this study, A549 lung epithelial cells were exposed to 15 nm NM300K or 59 nm PVP-coated Ag-NPs under two different conditions. Under these two conditions, the cells received the same total sub-lethal concentration of Ag-NPs, but the dose was either administered over a 24 hour period (acute exposure) or split over four successive days (repeated exposure). These two types of Ag-NPs were chosen as PVP-coated particles were hypothesized to dissolve more slowly than NM300K particles. EXAFS measurements confirmed this hypothesis, showing more rapid oxidation of Ag-0-NPs to Ag-I in cells exposed to NM300K. The intracellular Ag content was higher in cells exposed to NM300K, and higher in cells following acute exposure than cells exposed to repeated doses. Whatever the exposure scenario, Ag-I bound to thiol-containing intracellular proteins. Both exposure regimens altered cellular metabolism, caused intracellular ROS accumulation and blocked cell cycle progression. DNA damage was only observed following acute exposure, as strand breaks in cells exposed to NM300K and oxidized DNA bases in cells exposed to Ag-PVP. This damage was concomitant with decreased DNA repair activities. Together, these results show that acute exposure of A549 cells to Ag-NPs induces stronger effects on DNA integrity than repeated exposure. Nevertheless, repeated exposure to a low concentration of Ag-NPs profoundly altered the cell's metabolism and blocked cell cycle progression, confirming that both exposure regimens have detrimental effects