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Évaluation des expositions aux pyréthrinoïdes par la modélisation toxicocinétique de données de biosurveillance : application à la population générale française
No full textPyrethroids are ubiquitous insecticides used in many sectors. Human populations are likely to be exposed by several environmental media (air, soil, food, products; etc.), which enter the human system through various routes (inhalation, ingestion and skin contact). While some compounds are more toxic that others, parent compounds are suspected of inducing neuronal and hormonal disturbances in humans. Urinary concentrations of pyrethroid metabolites, which can be common to several pyrethroids, are often the only biomarkers of exposure. These concentrations must then be compared with the external exposure doses, which are used as the reference values for regulatory thresholds. This project develops an approach to analyze measurements of biomarkers in urine and estimate global exposure to pyrethroids based on PBPK modeling of pyrethroids. First, a global PBPK model was developed to link the external exposure of four pyrethroids (permethrin, cypermethrin, cyfluthrin and deltamethrin) and their isomers to urinary concentrations of metabolites (cis- and trans-DCCA, 3-PBA, F-PBA and DBCA). The model simulates aggregate cumulative exposures by multiple pathways (inhalation, ingestion, and skin contact). The global model was evaluated with human toxicokinetic data and tested with realistic exposures for the French population. The global model was then used to estimate the exposures of the French general population to pyrethroids from biomarkers, as measured by the ENNS study conducted by Santé Publique France. To address the problem of nonuniqueness of inverse solutions related to cypermethrin and permethrin (i.e. share two common metabolites but no specific one), we proposed a methodology based on food consumption questionnaires. This thesis demonstrates the viability of generic PBPK modeling for pyrethroids and the potential of such a model to improve the interpretation of pyrethroid exposure biomarkers.Les pyréthrinoïdes sont des insecticides ubiquitaires utilisés dans de nombreux domaines et par ce fait, les populations humaines sont susceptibles d’y être exposées par plusieurs médias environnementaux (air, sol, aliments, produits etc.) et plusieurs voies (inhalation, ingestion et contact cutané). Le composé parent est suspecté d’induire des perturbations neuronales et hormonales chez l’humain et certains composés sont plus toxiques que d’autres. Les concentrations urinaires de métabolites des pyréthrinoïdes sont souvent les seuls biomarqueurs d’une exposition humaine et ces métabolites étant parfois communs à plusieurs pyréthrinoïdes, les biomarqueurs sont le reflet d’une exposition globale et non à un pyréthrinoïde spécifique. Ces imprégnations doivent être mises en regard des doses d’expositions externes qui sont les valeurs de référence utilisées pour fixer des seuils réglementaires. Le travail consiste à développer une approche basée sur la modélisation PBPK des pyréthrinoides afin d’analyser les mesures de biomarqueurs dans les urines. Tout d’abord, un modèle PBPK global a été développé pour relier l'exposition externe de quatre pyréthrinoïdes (perméthrine, cyperméthrine, cyfluthrine et deltaméthrine) et de leurs isomères aux concentrations urinaires de métabolites (cis- et trans-DCCA, 3-PBA, F-PBA et DBCA). Le modèle permet de simuler les expositions cumulées agrégées par des voies multiples (inhalation, ingestion et contact cutané). Le modèle PBPK global a été évalué avec des données toxicocinétiques humaines et testé avec des expositions réalistes pour la population française. Le modèle a ensuite été utilisé pour estimer les expositions de la population générale française à partir de biomarqueurs d’exposition. L’étude ENNS réalisée par Santé Publique France a été utilisée. Nous avons mis en évidence des problèmes d’identifiabilité liés à la cyperméthrine et la perméthrine (i.e. partagent deux métabolites communs, mais pas de spécifique) et avons proposé une méthodologie basée sur les questionnaires de consommation alimentaire. Ce travail de thèse souligne la possibilité d’établir un modèle PBPK générique pour les pyréthrinoïdes et sur son applicabilité pour améliorer l'interprétation des biomarqueurs d'exposition aux pyréthrinoïdes
Comparison of PM10 Sources Profiles at 15 French Sites Using a Harmonized Constrained Positive Matrix Factorization Approach
No full textInternational audienceReceptor-oriented models, including positive matrix factorization (PMF) analyses, are now commonly used to elaborate and/or evaluate action plans to improve air quality. In this context, the SOURCES project has been setup to gather and investigate in a harmonized way 15 datasets of chemical compounds from PM 10 collected for PMF studies during a five-year period (2012-2016) in France. The present paper aims at giving an overview of the results obtained within this project, notably illustrating the behavior of key primary sources as well as focusing on their statistical robustness and representativeness. Overall, wood burning for residential heating as well as road transport were confirmed to be the two main primary sources strongly influencing PM 10 loadings across the country. While wood burning profiles, as well as those dominated by secondary inorganic aerosols, present a rather good homogeneity among the sites investigated, some significant variabilities were observed for primary traffic factors, illustrating the need to better characterize the diversity of the various vehicle exhaust and non-exhaust emissions. Finally, natural sources, such as sea salts (widely observed in internal mixing with anthropogenic compounds), primary biogenic aerosols and/or terrigenous particles, were also found as non-negligible PM 10 components at every investigated site
Fire tests carried out in FCH JU Firecomp project, recommendations and application to safety of gas storage systems
No full textInternational audienceIn the event of a fire, composite pressure vessels behave very differently from metallic ones: the material is degraded, potentially leading to a burst without significant pressure increase. Hence, such objects are, when necessary, protected from fire by using thermally-activated devices (TPRD), and standards require testing cylinder and TPRD together. The pre-normative research project FireComp aimed at understanding better the conditions which may lead to burst, through testing and simulation, and proposed an alternative way of assessing the fire performance of composite cylinders. This approach is currently used by Air Liquide for the safety of composite bundles carrying large amounts of hydrogen gas
Sequential upscaling of multiphase dispersion in porous media
No full textInternational audienceIn this paper we consider the transport of a chemical species in a two phase system with exchange of matter at the interface (so-called active dispersion). The boundary conditions at the interface between the two phases existing within the pore space are either of thermodynamic equilibrium or of reactive type. Saturation changes with the exchange of matter at the interface. The medium itself is characterized by different levels of heterogeneity starting from the pore-scale. In this work, problems related to pore-scale to Darcy-scale upscaling and then to Darcy-scale to Large-scale upscaling are considered. The first upscaling [1] leads to different problems depending on the boundary conditions and various assumptions, in particular the role of the total mass exchange rate, non-standard terms, etc. The role of geometry, reaction rate on dispersion and tortuosity is investigated for simple 1D/2D/3D unit cells. The second upscaling is only considered for the case of a local non-equilibrium Darcyscale model in the case of small variations of density and viscosity with concentration. It leads to a complex coupled problem between Darcy-scale deviations and large-scale averaged values. In particular, the solution exhibits memory and history effects. An algorithm is proposed to solve for the case of small Damköhler numbers (the Diffusive Damköler for low Péclet numbers or the convective Damköhler for high Péclet numbers). The resulting large-scale model is of the non-equilibrium type. The algorithm allows for the calculation of large-scale effective properties such as large-scale relative permeability, large-scale mass exchange coeffcients as a function of the large-scale phase saturation
Mechanisms limiting the release of TiO 2 nanomaterials during photocatalytic cement alteration: the role of surface charge and porous network morphology
No full textSSCI-VIDE+ECI2D+CGEInternational audienceNanomaterials have been widely used in a wide range of manufactured products in order to improve / add new properties. Photocatalytic cement maintains clean and white wall fronts and also provide interesting air pollution-reducing properties due to photocatalytic activity of incorporated TiO2-NMs. However, despite these environmental benefits, there is evidence of the release of TiO2-NMs during cement use. Therefore, it is crucial to understand the parameters controlling TiO2-NMs release. Zêta potentials of TiO2-NMs were investigated from the unaltered core to the cement altered surface using simulated cement pore waters. The mineralogy and chemical composition of the altered layer were investigated using X-ray Diffraction (XRD) and micro X-ray fluorescence spectroscopy (micro-XRF). Finally, pore network morphology was fully analyzed using X-ray computed tomography at both micro and nano-scales (micro and nano-CT) and quantified using 3D morphological software (i-Morph). This study provides evidence that the TiO2-NMs release comes from a very thin “active surface layer” (thickness less than 20 µm) where both cement surface chemistry and the pore network appears to be favorable for the TiO2-NMs diffusion. The pore volume connected to the surface with a throat size ≥1016 nm appears to control and be used as a predictor for TiO2-NMs release
Comprendre les processus de formation d'aérosols organiques dans l'atmosphère à l'aide de marqueurs moléculaires : une approche combinée mesures-modèle
No full textOrganic aerosols (OA) account for a large fraction of ambient air particulate matter and have strong impacts on air quality and climate. As their sources and atmospheric formation processes, notably for secondary OA (SOA), are still not fully understood, their concentrations are often underestimated by air quality models. This work aimed at improving OA modelling by implementing specific organic molecular marker emissions and formation processes into the chemistry-transport model CHIMERE. It was based on the comparison of model outputs with measurements from field studies performed in the Paris region (suburban site of SIRTA, 25 km SW of Paris) over 2015 and 10 French urban locations in winter 2014-2015. 25 biogenic and anthropogenic SOA markers have been quantified in both, particulate and gas phases and the formation pathways of 10 have been developed and simulated using CHIMERE. The evolution of levoglucosan concentrations (biomass burning marker) has been also modeled. The results obtained showed that sources and precursor emissions (missing or underestimated), radical concentrations (NO, HO2 and RO2) and the lack of formation pathways, are key parameters for the simulation of SOA markers. Gas/particle partitioning seemed poorly linked to the T°C while the inclusion of hydrophilic non-ideal partitioning, usually neglected, seemed essential. Levoglucosan was well simulated, even if some underestimations existed in some regions. A significant theoretical gaseous fraction was also highlighted. The model/measurements comparison of molecular markers is a powerful tool to evaluate precursor emissions, physicochemical processes and in the end, to estimate OA sources.L’aérosol organique (AO) constitue une large fraction des particules de l’air ambiant qui ont des impacts majeurs sur la qualité de l’air et le climat. Ses sources et processus de formation, surtout pour l’AO secondaire (AOS), sont encore méconnus induisant sa sous-estimation par les modèles de qualité de l’air. Ce travail a pour objectif d’améliorer la modélisation de l’AO en implémentant des émissions et processus de formation de marqueurs moléculaires organiques dans le modèle de chimie-transport CHIMERE. Il est basé sur la comparaison entre des sorties de modèle et de mesures réalisées en région parisienne (site périurbain du SIRTA, 25 km SO de Paris) en 2015 et sur 10 sites urbains en hiver 2014-2015. 25 marqueurs d’AOS biogénique et anthropique ont été quantifiés en phase particulaire et gazeuse et la formation de 10 a été simulée. L’évolution des concentrations en lévoglucosan (marqueur de la combustion de biomasse) a aussi été modélisée. Les résultats ont montré que les émissions de sources ou précurseurs (manquantes ou sous-estimées), les concentrations en radicaux (NO, HO2 et RO2) et le défaut de voies de formation, sont des paramètres clés pour la simulation des marqueurs d’AOS. Une faible dépendance à la T°C du partage gaz-particule a été observée alors que le partage hydrophile non idéal, souvent négligé, semble essentiel. Le lévoglucosan est bien modélisé, même si des sous-estimations existent dans certaines régions et une importante fraction gazeuse théorétique a été mise en évidence. La comparaison mesures/modèle de marqueurs moléculaires est un outil puissant pour évaluer les émissions, les processus physico-chimiques et à terme, estimer les sources d’AO
Determination of maternal and foetal distribution of cis- and trans-permethrin isomers and their metabolites in pregnant rats by liquid chromatography tandem mass spectrometry (LC-MS/MS)
No full textInternational audienceWe developed a method to quantify cis-permethrin and trans-permethrin and their metabolites in several biological matrices in pregnant rats and foetuses using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The objective was to quantify cis-permethrin and trans-permethrin in faeces, kidney, mammary gland, fat and placenta in mothers and in both maternal and foetal blood, brain and liver. The metabolites cis-3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (cis-DCCA), trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-(1-cyclopropane) carboxylic acid (trans-DCCA) and 3-phenoxybenzoic acid (3-PBA) were measured in blood, liver and urine. Sample preparation was performed by liquid-liquid extraction. A purification step was not carried out except for the more complex biological samples (fat, mammary glands and faeces). Validation parameters including specificity, linearity, matrix effect, limits of quantification (LOQs), accuracy and precision were evaluated. The recoveries of target compounds ranged from 47 to 136%. LOQs were in the range 4 to 80 ng/mL for permethrin isomers and 4 to 800 ng/mL for their respective metabolites. Intra- and inter-batch precision and accuracy in matrix were better than 15%. The validated method was applied in a preliminary toxicokinetic study in pregnant rats with oral dosing of 50 mg/kg permethrin. In pregnant rats, permethrin isomers and their metabolites were quantified in all requested matrices except maternal liver and blood for trans-permethrin and cis-DCCA respectively. In foetuses, cis- and trans-permethrin were also quantified, demonstrating that the method is suitable for the analysis of foetal distribution of permethrin in toxicokinetic studies
Caractérisation de l’exposition environnementale spatialisée à un pyréthrinoïde en Picardie
No full textInternational audiencePesticides are present in all areas of the environment and absorbed via many pathways (food, water, soil, and air). To characterize environmental exposures in detail, it is first necessary to combine within the same analysis data on the population’s lifestyles and on the local contamination of environmental media at appropriate resolutions and over large areas. As part of this pilot study,the objective of the CartoExpo project was to test the feasibility of an integrated methodology to map exposure indicators for small-area resolutions and short time intervals. To illustrate the approach, contamination of the general population was studied for a pyrethroid (cypermethrin) in the Picardy region (Northern France). For atmospheric dispersion, an innovative statistical meta-model method was developed, based on a machine learning technique that used a large database of simulations on a representative parcel. The meta-model was then applied to cypermethrin application at three-hourly intervals on all agricultural parcels in the Picardy region. Multimedia exposure models are needed to: 1) estimate emissions from soil and plant volatilization phenomena on agricultural land, 2) quantify contamination of local food products (excluding home vegetable gardens) due to proximity to agricultural land,a nd3)combine external exposures. Characterizing exposure involves numerous uncertainties, primarily about the assumptions underlying the different modeling approaches, and the representativeness and accuracy of the integrated data. Further measured and modeled data are therefore needed to validate the different approaches.Les expositions aux pesticides se caractérisent par la multiplicité des voies d’exposition (alimentation, eau, sol, air) liée à leur présence dans l’ensemble des milieux environnementaux. Pour une caractérisation fine des expositions environnementales, un premier verrou réside dans la capacité à rassembler au sein d’un même système d’analyse un ensemble de données combinant le mode de vie des populations et la contamination locale des milieux environnementaux sur des résolutions spatiales appropriées et des territoires étendus (échelles régionales ou nationales). Dans le cadre de cette étude pilote, l’objectif du projet CartoExpo était de tester la faisabilité d’une méthodologie intégrée pour la cartographie d’indicateurs d’exposition sur des résolutions spatiales et temporelles fines. Pour illustrer la démarche, la contamination de la population générale est étudiée pour un pyréthrinoïde (la cyperméthrine) sur la Picardie en considérant les voies d’ingestion (eau, sol, aliments) et d’inhalation (gaz et aérosol). Pour la dispersion atmosphérique, une méthode innovante de métamodèle statistique a été développée. Elle repose sur une technique d’apprentissage automatique à partir d’une vaste base de données de simulations sur une parcelle élémentaire. Le métamodèle est dans un deuxième temps appliqué aux épandages relevés à une fréquence tri-horaire sur l’ensemble des parcelles agricoles en région Picardie. Des modèles d’exposition multimédia sont nécessaires pour 1) estimer les flux d’émission liés aux phénomènes de volatilisation du sol et des plantes au niveau des parcelles agricoles, 2) quantifier la contamination des produits alimentaires locaux (hors champ : jardin potager) liée à la proximité des parcelles agricoles et 3) combiner l’exposition externe. L’exercice de caractérisation de l’exposition comporte cependant de nombreux manques et incertitudes dont l’impact, dans un sens ou dans l’autre, est à ce stade difficile à quantifier. Le besoin de valider les approches mises en œuvre nécessite de mobiliser des données (mesurées ou modélisées) supplémentaires
Effect of short exposure to radiofrequency electromagnetic fields on saliva biomarkers: a study on the electrohypersensitive individuals
No full textInternational audienceContext: Some individuals are reporting being sensitive to electromagnetic fields. They report some unspecific symptoms like headeache, sleep disruption, heart palpitations, itching, etc. The lack of scientific objective links between EHS symptoms and EMF exposure renders the diagnosis of EHS more complex.Purpose: Our present work aimed to look for the effect of RF EMF exposure on saliva alpha amylase (AA) and other biological markers such as cortisol and IgA in EHS individuals.Participants and methods: Ten EHS individuals participated in this double-blind provocation study. They were aged between 35 and 63yr. Experiment consisted of two sessions (sham and real exposure). No external EMF sources were allowed, and the exposure consisted of a series of EMF signals emitted from a generator (Rhode & Schwarz) and a horn antenna (Schwarzbeck BBHA9120b). Consecutive RF signals were applied: GSM 900, GSM 1800, DECT, and Wi-Fi signals for 5min each.Results: Exposure to 4 consecutive radiofrequency signals did not show any significant modification (p>.05) on the saliva AA, cortisol or immunoglobulin A concentrations in the electrohypersensitive individuals.Conclusions: Our study, under current conditions, do not presently allow us to propose an identification of marker for EHS
Impact of cerebral radiofrequency exposures on oxidative stress and corticosterone in a rat model of Alzheimer's disease
No full textInternational audienceAlzheimer´s diseases (AD) is the most common type of neurodegenerative disease leading to dementia. The cause of AD remains unknown, however several studies suggested that mobile phone radiofrequency electromagnetic fields (RF-EMF) exposures interacted with AD memory deficits in rodent models. Here we aimed to test the hypothesis that RF-EMF exposure may modify memory through corticosterone and oxidative stress in a rat model of AD. Long-Evans rats were healthy controls or AD models. AD rats received continuous intracerebroventricular infusion with ferrous sulphate, beta amyloid (βA) 1-42 peptide and buthionine-sufloximine (Lecanu, 2006). RF-EMF exposures were performed to the head for 1 month (5 days/week, 15 or 45 min/day in restraint) to mimic cell phone use. To look for hazard threshold, repeated exposures were set to reach high brain averaged specific absorption rates (BASAR): 1,5 W/Kg (15 min), 6 W/Kg (15 min) or 6 W/Kg (45 min). The sham group exposure was 0 W/kg (45 min). Endpoints were spatial memory in the radial maze, plasmatic corticosterone, heme oxygenase 1 (HO1) and neurofibrillary tangles. Results indicated that AD rats had increased thioflavine and HO1 staining, reduced memory performances and similar corticosterone level compared to healthy rats. In AD rats, reduced corticosterone and increased hippocampal HO1 staining were observed after the 6 W/kg 45 min exposure. There was no RF-EMF effect on memory and cortical HO1. In healthy rats, increased cortical HO1 staining was observed after the 6 W/kg 45 min exposure. There was no RF-EMF effect on memory, hippocampal HO1 staining or corticosterone. According to our data, neither AD nor healthy rats showed modified memory after RF-EMF exposures. Unlike healthy rats, AD rats showed higher hippocampal oxidative stress and reduced corticosterone after our highest BASAR exposures. This data may support the hypothesis of a specific fragility related to neurodegenerative disease towards RF-EMF exposures. Further studies should be performed to replicate this data