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VIVD: Virtual in vitro distribution model for the mechanistic prediction of intracellular concentrations of chemicals in in vitro toxicity assays
No full textInternational audienceIn vitro toxicity testing routinely uses nominal treatment concentrations as the driver for measured toxicity endpoints. However, test compounds can bind to the plastic of culture vessels or interact with culture media components, such as lipids and albumin. Additionally, volatile compounds may partition into the air above culture media. These processes reduce the free concentrations of compound to which cells are exposed. Models predicting the freely dissolved concentrations by accounting for these interactions have been published. However, these have only been applied to neutral compounds or assume no differential ionisation of test compounds between the media and cell cytoplasm. Herein, we describe an in vitro distribution model, based on the Fick-Nernst Planck equation accounting for differential compound ionisation in culture medium and intracellular water. The model considers permeability of ionised and unionised species and accounts for membrane potential in the partitioning of ionised moieties. By accounting for lipid and protein binding in culture medium, binding to cell culture plastic, air-partitioning, and lipid binding in the cell, the model can predict chemical concentrations (free and total) in medium and cells. The model can improve in vitro in vivo extrapolation of toxicity endpoint by determining intracellular concentrations for translation to in vivo
Insights into possibilities for grouping and read-across for nanomaterials in EU chemicals legislation
No full textInternational audienceThis paper presents a comprehensive review of European Union (EU) legislation addressing the safety of chemical substances, and possibilities within each piece of legislation for applying grouping and read-across approaches for the assessment of nanomaterials (NMs). Hence, this review considers both the overarching regulation of chemical substances under REACH (Regulation (EC) No 1907/2006 on registration, evaluation, authorization, and restriction of chemicals) and CLP (Regulation (EC) No 1272/2008 on classification, labeling and packaging of substances and mixtures) and the sector-specific pieces of legislation for cosmetic, plant protection and biocidal products, and legislation addressing food, novel food, and food contact materials. The relevant supporting documents (e.g. guidance documents) regarding each piece of legislation were identified and reviewed, considering the relevant technical and scientific literature. Prospective regulatory needs for implementing grouping in the assessment of NMs were identified, and the question whether each particular piece of legislation permits the use of grouping and read-across to address information gaps was answered
Rejets de micropolluants : un essai de comparaison économique entre traitement et substitution à la source
No full textInternational audienceThe numerous micropollutants generated by human activity are likely to significantly alter the quality of watercourses, especially when crossing large agglomerations. The study deals with the economic efficiency of different approaches to the management of urban micropollutants: we compare the cost of not emitting micropollutant streams from an agglomeration, either by substituting chemicals them at source, or by tertiary treatment in urban wastewater treatment plants. This comparison is carried out in two contrasting contexts of pollution : in the first case, we focused on current hazardous substances of the WFD (i.e. regulated substances) and in a second one we selected a list of 23 additional emerging substances. The comparison between treatment and substitution is carried out for the case of the wastewater treatment plant of a city of 200,000 eq.hab and the results tend to show that the substitution costs are lower than the costs of tertiary treatment by nanofiltration and activated carbon. However, given numerous uncertainties and assumptions, this exploratory study should be confirmed by more in-depth work, including other micropollutants and other tertiary treatment techniques. It anyway already appears to signal the interest of preventive and integrated strategies to control chemical risks.Les nombreux micropolluants générés par l’activité humaine sont susceptibles d’altérer significativement la qualité des cours d’eau, notamment à la traversée des grandes agglomérations. L’étude s’intéresse à l’efficacité économique de différentes approches de gestion des micropolluants urbains : nous comparons le coût de ne pas émettre dans le milieu aquatique les flux de micropolluants d’une agglo - mération, soit en substituant les produits chimiques en cause à la source, soit en les éliminant des rejets d’eaux usées par traitement complémentaire en station de traitement des eaux usées urbaines. Afin d’étudier l’influence de l’étendue de la contamination chimique prise en compte, un premier scénario se focalise sur des substances prioritaires dangereuses actuelles de la directive cadre sur l’eau (DCE) (donc des substances réglementées) et, dans un second temps, on a retenu une liste de 23 substances émergentes supplémen - taires. On compare le traitement et la substitution pour le cas type de la station d’épuration d’une ville de 200000 équivalent-habitant, et les résultats font apparaître que la stratégie de substitution semble en général plus « coût-efficace » que celle de traitement complémentaire par nanofiltration ou par charbon actif. Toutefois, ces résultats sont dépendants des nombreuses incertitudes et hypothèses et devraient être confirmés par des travaux plus approfondis, incluant notamment d’autres micropolluants et une description plus fine des coûts et bénéfices. Ils attirent l’attention sur l’intérêt de stratégies préventives intégrées de lutte contre les effets des substances chimiques
Differential activity of BPA, BPAF and BPC on zebrafish estrogen receptors in vitro and in vivo
No full textInternational audienceThe high volume production compound bisphenol A (BPA) is of environmental concern largely because of its estrogenic activity. Consequently, BPA analogues have been synthesized to be considered as replacement molecules for BPA. These analogues need to be thoroughly evaluated for their estrogenic activity. Here, we combined mechanism zebrafish-based assays to examine estrogenic and anti-estrogenic activities of BPA and two of its analogues, bisphenol AF (BPAF) and bisphenol C (BPC) in vitro and in vivo. In vitro reporter cell lines were used to investigate agonistic and antagonistic effects of the three bisphenols on the three zebrafish estrogen receptors. The transgenic Tg(5 × ERE:GFP) and Cyp19a1b-GFP zebrafish lines were then used to analyze estrogenic and anti-estrogenic responses of the three bisphenols in vivo. BPA, BPAF and BPC were agonists with different potencies for the three zebrafish estrogen receptors in vitro. The potent zfERα-mediated activity of BPA and BPAF in vitro resulted in vivo by activation of GFP expression in zebrafish larvae in the heart (zfERα-dependent) at lower concentrations, and in the liver (zfERβ-dependent) at higher concentrations. BPC induced zfERβ-mediated luciferase expression in vitro, and the zfERβ agonism led to activation of GFP expression in the liver and the brain in vivo. In addition, BPC acted as a full antagonist on zfERα, and completely inhibited estrogen-induced GFP expression in the heart of the zebrafish larvae. To summarize, applying a combination of zebrafish-based in vitro and in vivo methods to evaluate bisphenol analogues for estrogenic activity will facilitate the prioritization of these chemicals for further analysis in higher vertebrates as well as the risk assessment in humans
Underground rock dissolution and geomechanical issues
No full textInternational audienceThis paper deals with the problem of the dissolution of soluble underground rocks and the geomechanical consequences such as subsidence, sinkholes and underground collapse. In this paper, the rock dissolution and the induced underground cavities aremodeled using a Diffuse Interface Model. We describe briefly the method. We used to perform the transition (upscaling) from a multiphysics problem formulated at the microscopic scale level (pore-scale) to the macroscopic scale level (Darcy-scale). Rock material considered in this paper is gypsum, despite that the developed method is also suitable for more soluble rocks. The mechanical consequences of dissolution are analyzed fortwo theoretical configurations, i.e., lens and pilla
Multiple visions of the future and major environmental scenarios
No full textScientific programming in environmental science often relies on short-term (3 to 5 years) trend-based projections for contextual elements like the demography or the economy to construct or justify its choice of priorities. However, this approach does not take into account numerous factors of change or disruption over a longer term (10 to 20, or even 50 years), although a decade or two are needed to effectively deal with the stakes of research. These stakes become more acute over the long term, as consequences of predicted changes (e. g. climate) or other factors such as pollution, biodiversity erosion, reduction of ecosystemic services.... This complex question justifies turning to a foresight approach. Because it enables tipping points to be envisaged for some key variables of the system studied (in this case, the environment), the scenario method seems well adapted to proposing several contrasting visions of the future.. The research question is: how a large screening of international studies on environmental scenarios can help framing the reflection on research priorities about environment? To help take its strategic reflection forward, in June 2015 the French national research alliance for the environment (AllEnvi) commissioned its transversal foresight group to identify the major families of scenarios described in foresight studies dealing with the environment since 2000. The summary of the 307 scenarios produced by analyzing 99 international studies highlighted 11 possible societal and environmental pathways. Analyzing these families of scenarios thus makes it easier to clarify the multiple roles that science can play, according to contrasting dynamics. Consequently, this study shows how a systematic review of foresight studies and their related visions of the future of environment can stimulate and enlighten the reflection on the ways societies can (re)define their future, by combining environmental, governance and social sciences
Impact of the chemical structure on amphiphilic properties of sugar-based surfactants: A literature overview
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Understanding the Thermal Runaway of Ni-Rich Lithium-Ion Batteries
No full textInternational audienceThe main safety issue pertaining to operating lithium-ion batteries (LIBs) relates to their sensitivity to thermal runaway. This complex multiphysics phenomenon was observed in two commercial 18650 Ni-rich LIBs, namely a Panasonic NCR GA and a LG HG2, which were based on Li(Ni 0.8 Co 0.15 Al 0.05)O 2 (NCA) and Li(Ni 0.8 Mn 0.1 Co 0.1)O 2 (NMC811), respectively, for positive electrodes, in combination with graphite-SiO x composite negative electrodes. At pristine state, the batteries were charged to different levels of state of charge (SOC) (100% and 50%) and were investigated through thermal abuse tests in quasi-adiabatic conditions of accelerating rate calorimetry (ARC). The results confirmed the proposed complete thermal runaway of exothermic chain reactions. The different factors impacting the thermal runaway kinetics were also studied by considering the intertwined impacts of SOC and the related properties of these highly reactive Ni-rich technologies. All tested cells started their accelerated thermal runaway stage at the same self-heating temperature rate of~48 • C/min. Regardless of technology, cells at reduced SOC are less reactive. Regardless of SOC levels, the Panasonic NCR GA battery technology had a wider safe region than that of the LG HG2 battery. This technology also delayed the hard internal short circuit and shifted the final venting to a higher temperature. However, above this critical temperature, it exhibited the most severe irreversible self-heating stage, with the highest self-heating temperature rate over the longest duration
La pollution de l’air en Chine
No full textInternational audienceDurant les deux dernières décennies, la Chine a vécu une expansion économique sans précédent dans l’histoire moderne, passant de pays en voie de développement à locomotive pour le reste du monde dans bien des domaines technologiques. Ce développement fulgurant, qui s’est accompagné d’un exode rural vers les grands centres urbains, a exercé une forte pression sur les ressources naturelles et a très largement affecté la qualité de l’air. Des mesures de gestion de la pollution de plus en plus drastiques ont permis de limiter la pollution de l’air et même d’améliorer la situation de façon spectaculaire au cours de ces cinq dernières années. La qualité des chercheurs chinois de ce domaine, le pragmatisme des autorités et l’adhésion d’une population concernée ont permis de relever ce défi, qui place désormais la Chine au rang de pays leader dans le développement des nouvelles énergies et des technologies innovantes pour préserver l’environnement. Les parties prenantes sont conscientes des efforts encore à réaliser et des nouveaux défis liés notamment au secteur agricole, à la production et stockage d’énergie, à la réduction des émissions de méthane et aux concentrations d’ozone qui restent en légère augmentation. Comme dans le reste du monde, l’enjeu sera dans le futur de bien coordonner les politiques de contrôle des émissions de polluants avec celles liées au réchauffement climatique et de relever nombre de défis technologiques dans les secteurs de l’énergie, la mobilité, l’agriculture et l’approvisionnement en eau potable
Population pharmacokinetic reanalysis of a Diazepam PBPK model: a comparison of Stan and GNU MCSim
No full textInternational audienceThe aim of this study is to benchmark two Bayesian software tools, namely Stan and GNU MCSim, that use different Markov chain Monte Carlo (MCMC) methods for the estimation of physiologically based pharmacokinetic (PBPK) model parameters. The software tools were applied and compared on the problem of updating the parameters of a Diazepam PBPK model, using time-concentration human data. Both tools produced very good fits at the individual and population levels, despite the fact that GNU MCSim is not able to consider multivariate distributions. Stan outperformed GNU MCSim in sampling efficiency, due to its almost uncorrelated sampling. However, GNU MCSim exhibited much faster convergence and performed better in terms of effective samples produced per unit of time