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

The enrichment of an alkaliphilic biofilm consortia capable of the anaerobic degradation of isosaccharinic acid from cellulosic materials incubated within an anthropogenic, hyperalkaline environment.

Anthropogenic hyper-alkaline sites provide an environment that is analogous to proposed cementitious geological disposal facilities (GDF) for radioactive waste. Under anoxic, alkaline conditions cellulosic wastes will hydrolyse to a range of cellulose degradation products (CDP) dominated by isosaccharinic acids (ISA). In order to investigate the potential for microbial activity in a cementitious GDF, cellulose samples were incubated in the alkaline (∼pH 12), anaerobic zone of a lime kiln waste site. Following retrieval, these samples had undergone partial alkaline hydrolysis and were colonised by a Clostridia dominated biofilm community, where hydrogenotrophic, alkaliphilic methanogens were also present. When these samples were used to establish an alkaline CDP fed microcosm, the community shifted away from Clostridia, methanogens became undetectable and a flocculate community dominated by Alishewanella sp. established. These flocs were composed of bacteria embedded in polysaccharides and protein stabilised by extracellular DNA. This community was able to degrade all forms of ISA with >60% of the carbon flow being channelled into extracellular polymeric substance (EPS) production. This study demonstrated that alkaliphilic microbial communities can degrade the CDP associated with some radioactive waste disposal concepts at pH 11. These communities divert significant amounts of degradable carbon to EPS formation, suggesting that EPS has a central role in the protection of these communities from hyper-alkaline conditions

ISFET Based Microsensors for Environmental Monitoring

The use of microsensors for in-field monitoring of environmental parameters is gaining interest due to their advantages over conventional sensors. Among them microsensors based on semiconductor technology offer additional advantages such as small size, robustness, low output impedance and rapid response. Besides, the technology used allows integration of circuitry and multiple sensors in the same substrate and accordingly they can be implemented in compact probes for particular applications e.g., in situ monitoring and/or on-line measurements. In the field of microsensors for environmental applications, Ion Selective Field Effect Transistors (ISFETs) have a special interest. They are particularly helpful for measuring pH and other ions in small volumes and they can be integrated in compact flow cells for continuous measurements. In this paper the technologies used to fabricate ISFETs and a review of the role of ISFETs in the environmental field are presented

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

National audienc

Evaluation of tritiated water diffusion through the Toarcian clayey formation of the Tournemire experimental site (France)

Through-diffusion experiments with tritiated water were performed on argillaceous samples from various zones of the Tournemire test site. It was intended to evaluate the homogeneity of the transport property of unfracturated samples and the influence of the orientation and the nature of the samples (presence of an opened fracture or a pre-existing tectonic fracture filled with calcite and pyrite). Homogeneous values of the tritiated water (HTO) effective diffusion coefficients were deduced from experiments carried out when diffusion occurred parallel to the stratigraphic bedding, with an apparent sensitivity to experimental conditions. Anisotropy was significant, De(HTO) perpendicular to the bedding being 1/3 lower than that parallel to the bedding. The observed fractures of the samples created by mechanical stress and partial dehydration during sawing and the presence of a pre-existing opened fracture did not affect the effective diffusion coefficients of tritiated water, which is probably due to the healing ability of the clayey medium during the re-saturation phases of the equilibrium steps performed prior to the diffusion experiments. On the contrary, a significant decrease of this transport parameter was induced by the occurrence of a pre-existing tectonic fracture, which was assigned to the dense structure of the filling phases. © 2007 Elsevier B.V. All rights reserved

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

International audienc