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

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

Nanomaterial genotoxicity: The case of silver nanoparticles

International audienc

Assessment of exposure to airborne carbon nanotubes by laser-induced breakdown spectroscopy analysis of filter samples

International audienceExposure assessment is a key step in the evaluation of the risk induced by the handling of engineered nanomaterials. It is a very complex task, because several properties of nanoparticles are assumed to have an effect on their hazards. For exposure monitoring at the workplace, real-time onsite measurements are commonly implemented to measure the particles size and number density, whereas the sampled material is subsequently analysed by electron microscopy. A complementary approach would consist in doing onsite chemical analysis of the filter samples, in order to routinely monitor a potential chronic exposure. Laser-induced breakdown spectroscopy (LIBS) has distinctive advantages for this purpose. Therefore, this work aims at evaluating the performances of LIBS to assess the exposure to airborne carbon nanotubes (CNTs) at the workplace. As carbon is a ubiquitous element in the environment, our strategy was to target metal impurities in CNTs, aluminum and iron in our case. Then, we proceeded in three steps. First, we optimized the choice of the filter type to get the lowest detection limit for both elements. Secondly, this filter was used to quantitatively measure deposited CNTs. Eventually, we conducted an onsite measurement campaign in an industrial CNT production plant to evaluate the exposure in a real situation. We demonstrated that we could reach a detection limit for CNTs compliant with the current NIOSH recommendation of 1 μg m−3, and that the detected CNTs during the onsite campaign in areas accessible to workers were at an extremely low concentration, several orders of magnitude lower than this recommendation

Minimising the risk posed by TiO2 nanomaterials used in sunscreen throughout the entire product lifecycle

Sunscreens are of emerging concern regarding both human and environmental health. While TiO2 nanoparticles used as UV-blockers may offer a safer alternative to organic filters, their fate and impact and resulting regulation are still under consideration, largely related to the potential risk of nanotechnology-based products. After leaving the skin either through bathing or cleaning, the TiO2 nanomaterials contained in the sunscreen can be released into rivers, lakes, sea shores, and/or sewage treatment plants. Their fate and impact in these different systems is largely determined by the surface properties, i.e. the coating type and lifetime. This project aims to develop the eco-design of sunscreens through the minimization of risks associated with nanomaterials incorporated into the formulation. All stages of the cream life cycle must be considered in this light, from its manufacture to its end of life, through its use by the consumer and its impact on the exposed environment. By considering each development stage of the sunscreen, from the choice of UV-blocker and its integration into a cosmetic formulation, to the knowledge of the risk involved in this choice all along the product lifecycle, an eco-design approach can be achieved and risk can be minimized. The present work combines industrial companies specialising in cosmetic formulation with academic research experts in the fields of exposure, toxicity and lifecycle assessment. Sunscreen fabrication, risk for the consumer by dermal exposure, risk for the direct aquatic environment and risk related to the end of life of the product are as many key steps of the sunscreen lifecycle that were investigated in this project

Eco-SUN for Eco-design of sunscreen using titanium dioxide nanoparticles

Among cosmetics and personal care products, sunscreen products are of emerging concern regarding both human and environmental health. The fate and impact of mineral nanoparticulate UV-blockers, such as TiO2 nanomaterials, is under consideration from a regulatory perspective due to their potential impact. Once leaving the skin either through bathing or everyday usage and cleaning, the nanomaterials contained in the sunscreen can be released into rivers, lakes, sea shores, and/or sewage treatment plants. The nanomaterial behaviour, fate and impact in these different systems is largely determined by its surface properties, (e.g. the nanomaterial coating type) and lifetime. Here we present the first result of the Eco-SUN research program aimed at developing the eco-design of sunscreens through the minimization of risks associated with nanomaterials incorporated into the formulation. Different stages of the cream lifecycle are considered from its manufacture to its end of life, through its use by the consumer and its impact on the exposed environments. Reducing the potential release and / or toxicity of the nanomaterial from the cream is a decisive criterion for its eco-design. Different relevant TiO2 UV-blockers have been selected to integrate a typical o/w formulation as case studies. The resulting sunscreen were characterised in terms of nanomaterial localisation, sun protection factor and photo-passivation. The risk for the consumer by dermal exposure was assessed using skin biopsies. Inflammation and skin penetration were evaluated. The risk for the aquatic environment directly expose was assessed both in terms of exposure and hazard. The release of nanomaterials from the sunscreen upon normal usage was studied in laboratory through simulated aging procedure. Two biological models, sea urchin and coral colonies, were selected as relevant endpoints to assess the marine ecotoxicity of the byproducts formed. Finally, the risk related to the end of life of the sunscreen through the removal with cleaning water followed by drainage to sewage treatment plants was evaluated by considering two opposite fate scenarios: (i) nanomaterial concentration in sewadge sludge later spread as fertilizer in agriculture, and (ii) nanomaterial suspension maintained in the treated water and released in river water. Thus, fate and impact in soil and river ecosystems were also studied

Fiber-optic pH sensor for in-situ applications

Communication to : First European Conference on Optical Chemical Sensors and Biosensors, Graz Autriche, du 12 au 15 avril, 1992SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : RM 1439 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Lifecycle and ompact of sunscreens using TiO2 nanomaterials

Among cosmetics and personal care products, sunscreen products are of emerging concern regarding both human and environmental health. The fate and impact of mineral nanoparticulate UV-blockers, such as TiO2 nanomaterials, is under consideration from a regulatory perspective due to their potential impact. Once leaving the skin either through bathing or everyday usage and cleaning, the nanomaterials contained in the sunscreen can be released into rivers, lakes, sea shores, and/or sewage treatment plants. The nanomaterial behaviour, fate and impact in these different systems is largely determined by its surface properties, (e.g. the nanomaterial coating type) and lifetime. Here we present the first result of the Eco-SUN research program aimed at developing the eco-design of sunscreens through the minimization of risks associated with nanomaterials incorporated into the formulation. Different stages of the cream lifecycle are considered from its manufacture to its end of life, through its use by the consumer and its impact on the exposed environments. Reducing the potential release and / or toxicity of the nanomaterial from the cream is a decisive criterion for its eco-design. Different relevant TiO2 UV-blockers have been selected to integrate a typical o/w formulation as case studies. The resulting sunscreen were characterised in terms of nanomaterial localisation, sun protection factor and photo-passivation. The risk for the consumer by dermal exposure was assessed using skin biopsies. Inflammation and skin penetration were evaluated. The risk for the aquatic environment directly expose was assessed both in terms of exposure and hazard. The release of nanomaterials from the sunscreen upon normal usage was studied in laboratory through simulated aging procedure. Two biological models, sea urchin and coral colonies, were selected as relevant endpoints to assess the marine ecotoxicity of the byproducts formed. Finally, the risk related to the end of life of the sunscreen through the removal with cleaning water followed by drainage to sewage treatment plants was evaluated by considering two opposite fate scenarios: (i) nanomaterial concentration in sewadge sludge later spread as fertilizer in agriculture, and (ii) nanomaterial suspension maintained in the treated water and released in river water. Thus, fate and impact in soil and river ecosystems were also studied

Safer by design sunscreen using titanium dioxide nanoparticles

Among cosmetics and personal care products, sunscreen products are of emerging concern regarding both human and environmental health. The fate and impact of mineral nanoparticulate UV-blockers, such as TiO2 nanomaterials, is under consideration from a regulatory perspective due to their potential impact. Here we present the first result of the Eco-SUN research program aimed at developing the eco-design of sunscreens through the minimization of risks associated with nanomaterials incorporated into the formulation. Different stages of the cream lifecycle are considered from its manufacture to its end of life, through its use by the consumer and its impact on the exposed environments. Reducing the potential release and / or toxicity of the nanomaterial from the cream is a decisive criterion for its ecodesign. Different relevant TiO2 UV-blockers have been selected to integrate a typical w/o formulation as case studies. The resulting sunscreens were characterised in terms of nanomaterial localisation, sun protection factor and photo-passivation. The risk for the consumer by dermal exposure will be assessed using skin biopsies, and evaluating inflammation and skin penetration. The risk for the aquatic environment directly exposed will be assessed both in terms of exposure and hazard. The release of nanomaterials from the sunscreen upon normal usage was studied in the laboratory through a simulated aging procedure. Two biological models, sea urchin and coral colonies, were selected as relevant endpoints to assess the marine ecotoxicity of the by-products formed. Finally, the risk related to the end of life of the sunscreen through the removal with cleaning water followed by drainage to sewage treatment plants will be evaluated by considering the scenarios of nanomaterial concentration in sewage sludge later spread as fertilizer in agriculture