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A spatio-temporal exposure-hazard model for assessing biological risk and impact
No full textInternational audienceWe developed a simulation model for quantifying the spatio-temporal distribution of contaminants (e.g., xenobiotics) and assessing the risk of exposed populations at the landscape level. The model is a spatio-temporal exposure-hazard model based on (i) tools of stochastic geometry (marked polygon and point processes) for structuring the landscape and describing the exposed individuals, (ii) a dispersal kernel describing the dissemination of contaminants from polygon sources, and (iii) an (eco)toxicological equation describing the toxicokinetics and dynamics of contaminants in affected individuals. The model was implemented in the briskaR package (biological risk assessment with R) of the R software. This article presents the model background, the use of the package in an illustrative example, namely, the effect of genetically modified maize pollen on nontarget Lepidoptera, and typical comparisons of landscape configurations that can be carried out with our model (different configurations lead to different mortality rates in the treated example). In real case studies, parameters and parametric functions encountered in the model will have to be precisely specified to obtain realistic measures of risk and impact and accurate comparisons of landscape configurations. Our modeling framework could be applied to study other risks related to agriculture, for instance, pathogen spread in crops or livestock, and could be adapted to cope with other hazards such as toxic emissions from industrial areas having health effects on surrounding populations. Moreover, the R package has the potential to help risk managers in running quantitative risk assessments and testing management strategies
Pollution particulaire à grande échelle et empreinte chimique des aérosols sulfatés volcaniques issus de l'éruption Holuhraun de 2014-2015 du volcan Bárðarbunga (Islande)
No full textInternational audienceVolcanic sulfate aerosols play a key role in air quality and climate. However, the rate of oxidation of sulfur dioxide (SO2) precursor gas to sulfate aerosols (SO4^2-) in volcanic plumes is poorly known, especially in the troposphere. Here we determine the chemical speciation as well as the intensity and temporal persistence of the impact on air quality of sulfate aerosols from the 2014-2015 Holuhraun flood lava eruption of Icelandic volcano Bárðarbunga. To do so, we jointly analyse a set of SO2 observations from satellite (OMPS and IASI) and ground-level measurements from air quality monitoring stations together with high temporal resolution mass spectrometry measurements of an Aerosol Chemical Speciation Monitor (ACSM) performed far from the volcanic source. We explore month/year long ACSM data in France from stations in contrasting environments, close and far from industrial sulfur-rich activities. We demonstrate that volcanic sulfate aerosols exhibit a distinct chemical signature in urban/rural conditions, with NO3:SO4 mass concentration ratios lower than for non-volcanic background aerosols. These results are supported by thermodynamic simulations of aerosol composition, using the ISORROPIA II model, which show that ammonium sulfate aerosols are preferentially formed at a high concentration of sulfate, leading to a decrease in the production of particulate ammonium nitrate. Such a chemical signature is however more difficult to identify at heavily polluted industrial sites due to a high level of background noise in sulfur. Nevertheless, aged volcanic sulfates can be distinguished from freshly emitted industrial sulfates according to their contrasting degree of anion neutralization. Combining AERONET (AErosol RObotic NETwork) sunphotometric data with ACSM observations, we also show a long persistence over weeks of pollution in volcanic sulfate aerosols, while SO2 pollution disappears in a few days at most. Finally, gathering 6-month long datasets from 27 sulfur monitoring stations of the EMEP (European Monitoring and Evaluation Programme) network allows us to demonstrate a much broader large-scale European pollution, in both SO2 and SO4 , associated with the Holuhraun eruption, from Scandinavia to France. While widespread SO2 anomalies, with ground-level mass concentrations far exceeding background values, almost entirely result from the volcanic source, the origin of sulfate aerosols is more complex. Using a multi-site concentration-weighted trajectory analysis, emissions from the Holuhraun eruption are shown to be one of the main sources of SO4 at all EMEP sites across Europe and can be distinguished from anthropogenic emissions from eastern Europe but also from Great Britain. A wide variability in SO2:SO4 mass concentration ratios, ranging from 0.8 to 8.0, is shown at several stations geographically dispersed at thousands of kilometres from the eruption site. Despite this apparent spatial complexity, we demonstrate that these mass oxidation ratios can be explained by a simple linear dependency on the age of the plume, with a SO2-to-SO4 oxidation rate of 0.23 h−1. Most current studies generally focus on SO2, an unambiguous and more readily measured marker of the volcanic plume. However, the long persistence of the chemical fingerprint of volcanic sulfate aerosols at continental scale, as shown for the Holuhraun eruption here, casts light on the impact of tropospheric eruptions and passive degassing activities on air quality, health, atmospheric chemistry and climate
Placental transfer of xenobiotics in pregnancy physiologically-based pharmacokinetic models: Structure and data
No full textInternational audienceThe assessment of human fetal exposure to chemicals is a key to fully understand developmental toxicity. Maternal concentrations during pregnancy and cord blood concentrations at delivery are often used as a proxy of fetal exposure over pregnancy or at term, respectively. Pregnancy physiologically-based pharmacokinetic (pPBPK) models can serve as an alternative by simulating fetal exposure throughout gestation. The latter depends on the maternal pharmacokinetic absorption, distribution, metabolism and elimination (ADME) processes, but also largely on placental transfers. Various placental transfer structures are used in pPBPK models and they are informed by numerous data sources. In this paper, we reviewed the physiological and anatomical changes of the placenta during human pregnancy, and the various placental transfer sub-models which have been used in animal and human pPBPK modeling. Computational and experimental methods used to characterize placental transfers are presented and discussed for their potential contribution to the development or evaluation of pPBPK models. This review provides information to support a reasoned-decision upon the integration of placental transfer in pPBPK modeling to better investigate fetal toxicokinetics in silico
The strength in numbers: comprehensive characterization of house dust using complementary mass spectrometric techniques
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Compréhension et prédiction des effets des substances chimiques sur la dynamique de population de l'épinoche à trois épines en mésocosme
No full textIn ecotoxicology, experiments in artificial ecosystems (mesocosms) are of a great interest because they allow to evaluate the direct and indirect effects of toxicants at different levels of biological organization such as individuals, populations and ecosystems. However, mesocosm experiments are characterized by a low statistical power and a high risk of not detecting differences between control (without contaminant) and contaminated mesocosms when there is one. In this context, individual-based models based on the dynamic energy budget theory have been suggested as relevant tools to improve the analysis of mesocosm experiment results. Thus, the objective of this phD was to develop an individual-based model simulating the three-spined stickleback population dynamics in artificial streams. The knowledge on the biological model used, the three-spined stickleback, as well as the use of several available datasets from mesocosm experiments with or without tested chemicals allowed us to develop this model. Our individual-based model was first developed, calibrated and evaluated on data from three-spined stickleback population dynamics in mesocosms in control conditions. In a second step, the model was applied to several case studies where different chemical substances were tested in mesocosms. Simulation results have shown that the individual-based modelling approach seems promising for improving current assessments of the effects of chemicals. Indeed, our model helped us to have a better understanding of the modes of action of toxicants and a relevant extrapolation of ecotoxicity data measured in the laboratory on organisms to the population level.En écotoxicologie, les expériences en écosystème artificiel (mésocosme) présentent un intérêt certain car elles permettent d’évaluer les effets directs et indirects des contaminants à des niveaux d’organisation biologique tels que les individus, les populations et les écosystèmes. Cependant, les études en mésocosme sont caractérisées par une faible puissance statistique et un risque élevé de ne pas détecter de différence entre les mésocosmes contrôles (sans contaminant) et ceux contaminés lorsqu’il y en a un. Dans ce contexte, les modèles individu-centrés basés sur la théorie de « dynamic energy budget » ont été suggérés être des outils pertinents pour permettre une meilleure analyse des résultats d’expérience en mésocosme. L’objectif de cette thèse était donc de développer un tel modèle simulant la dynamique de population de l’épinoche à trois épines en rivière artificielle. Les connaissances sur le modèle biologique utilisé, l’épinoche à trois épines, ainsi que plusieurs jeux de données disponibles provenant d’expériences en mésocosmes avant ou sans substances chimiques testées ont été utilisés pour développer ce modèle individu-centré. Celui-ci a tout d’abord été développé, calibré et évalué sur des données de dynamiques de population d’épinoches à trois épines en condition contrôle en mésocosme. Dans un second temps, le modèle a été appliqué à plusieurs cas d’étude où différentes substances chimiques ont été testées en mésocosme. Les résultats de simulation ont montré que l’approche par modélisation individu-centrée semble prometteuse pour améliorer les évaluations actuelles des effets des substances chimiques. Celle-ci a notamment permis une meilleure compréhension des modes d’action des toxiques et une extrapolation pertinente des données d’écotoxicité mesurées en laboratoire sur les organismes au niveau populationnel
Activité et influence des préventeurs au sein d’une organisation à risque : le cas d’un site de production dans le secteur de la chimie pharmaceutique
No full textOHS specialists are central agents for risk management in companies. However, little knowledge about their real activities is available, in particular in the area of high-risk industries. The objective of this research is to understand how OHS specialists, through their activities and their interactions with the other employees, contribute to building safety in the context of a site classified as Seveso III “upper tier”. The research was organized around three axes. First of all, an ergonomic approach was conducted to describe the determinants, the aims and the characteristics of the activities of two OHS specialists in charge of tasks related to industrial safety. The results illustrate the great diversity of subjects they deal with as well as the importance of the relational dimension and the fragmented nature of their activity. Then, the second axis addressed the question of OHS specialists’ influence by using sociology of organizations framework. It aims at describing their roles and the sources of power they have. It appears that OHS specialists play the roles of expert, controller and coordinator with the various stakeholders of industrial safety, as the top management, the engineers, the operators, the human resources, the public authorities, etc. Finally, the third axe focused on the relationships between OHS specialists and the operators by addressing the issue of the definition and the application of rules for the manufacturing activities. This PhD work has illustrated the various forms of influence of OHS specialists on industrial safety and has stressed the importance of analyzing them in the specific context of the company.Les préventeurs représentent des acteurs centraux pour la gestion des risques au sein des entreprises. Cependant, peu de connaissances sont disponibles concernant leurs activités réelles, en particulier dans le domaine des industries à risques. L’objectif de cette recherche est de montrer comment les préventeurs, à travers leurs activités et leurs interactions avec les autres acteurs, contribuent à la construction de la sécurité dans le contexte d’un site classé SEVESO « seuil haut ». La recherche a été organisée autour de trois axes. Tout d’abord une démarche ergonomique a permis de décrire les déterminants, les buts et les caractéristiques des activités de deux préventeurs ayant des missions relatives à la sécurité industrielle. Les résultats illustrent la grande diversité de sujets qu’ils traitent ainsi que l’importance de la dimension relationnelle et le caractère fragmenté de leur activité. Le deuxième axe aborde ensuite l’influence des préventeurs en mobilisant la sociologie des organisations. Il vise à décrire les rôles et les sources de pouvoir dont disposent ces acteurs. Il ressort que les préventeurs jouent les rôles d’expert, de contrôleur et de coordinateur auprès des différents acteurs contribuant à la sécurité industrielle, tels que la direction, les ingénieurs, les opérateurs, les ressources humaines, les autorités de contrôles, etc. Enfin, le troisième axe s’est focalisé sur les liens entre les préventeurs et les opérateurs en abordant la question de l’élaboration et de l’application des règles qui cadrent les activités de fabrication. Ce travail de thèse a permis d’illustrer les diverses formes d’influence des préventeurs sur la sécurité industrielle et de souligner l’importance de les analyser dans le contexte spécifique de l’entreprise
Some key considerations when evaluating explosion severity of nanopowders
No full textInternational audienceProtection from explosion events requires the determination of key safety parameters like lower explosion limit, maximum explosion over-pressure, and maximum rate of pressure rise. These parameters are routinely obtained through standard tests performed typically either in a 20 L sphere or a 1 m 3 container. But several aspects are worth a closer investigation. Firstly, the test apparatus must be able to disperse a fairly uniform dust cloud. However, previous investigations showed that actually the current dispersion system can be improved. Indeed, as a function of the sample and the dispersion conditions, the dust concentration in the ignition zone can be significantly different from the nominal dust concentration. Moreover, due to agglomeration/fragmentation phenomena, the particle size distribution can greatly evolve during dust injection. Secondly, the influence of humidity on the explosivity is not considered in current standards. It is just stated that the relative humidity should be checked and noted down, though some provisions exist in American standards. Even when performing the powder injection with synthetic air, the water contained in the residual air of the sphere can impact the chemical reactions occurring during the explosion. Thirdly, the ignition delay time is sometimes modified to study the impact of the dust cloud turbulence on flame propagation but is often misunderstood. For instance, by decreasing the ignition delay time, the injection time of the powder becomes shorter for the same pressure difference. This modifies the dispersion kinetics and can change the particle size distribution. Finally, for very sensitive powders, pre-ignition can occur or the ignition energy sets at 10kJ can lead to an overdriving phenomenon. Maybe these aspects have not been thoroughly considered for micron powders. However, in the case of nanopowders, the importance of these influencing factors was shown in order to duly evaluate explosion parameters. Experimental evidences confirm these aspects and alternative solutions will be presented
Tests d'outils innovants pour la caractérisation haute résolution des sites pollués
No full textInternational audienceLa caractérisation de la pollution du milieu souterrain d’un site est un enjeu essentiel pour définir les actions de remédiation et atteindre les objectifs associés. Parmi les verrous récurrents à cette caractérisation, se situent la complexité des sites, les hétérogénéités géologiques des sols, les grandes différences de comportement et de mobilité des polluants d’intérêts. La compréhension de la distribution des polluants et des contextes physiques dans lesquels ils se situent représente une clé du succès d’une opération de remédiation.La caractérisation des pollutions, par l’intermédiaire d’un prélèvement classique d’eaux souterraines réalisé dans un piézomètre, fournit généralement une information trop partielle pour permettre d’établir un schéma conceptuel de qualité des milieux complexes. Dans pareil cas, des prélèvements multi niveaux et l’acquisition de données complémentaires aux données de qualité chimiques des eaux sont indispensables.Cette étude organise un atelier participatif pour tester différents outils innovants de caractérisation détaillée des matrices souterraines :Mesures de flux de nappe (sens, vitesse …),Mesures multiniveaux de la matrice eau (concentrations, flux…).Les résultats attendus portent sur des connaissances partagées des périmètres d’utilisation de ces outils (typologies de site, géologie, hydrogéologie, contaminants…), des conditions opérationnelles de leur mise en œuvre (conditions d’accès à la technique, facilités d’utilisation, compétences nécessaires, coûts associés, …), de leurs performances techniques (précisions, incertitudes, quantifications, …), de leurs limites (selon les différents contextes de sites…).Cette comparaison doit favoriser l’appropriation d’outils innovants (français et étrangers) pour une caractérisation détaillée de sites pollués (D-L-NAPL), permettant de mieux comprendre les dynamiques et le fonctionnement des systèmes. Elle pourrait permettre de proposer des schémas conceptuels plus précis pour une meilleure connaissance des transferts et une meilleure conception des opérations de remédiation
Future climatic drivers and their effect on PM10 components in Europe and the Mediterranean Sea
No full textInternational audienceMultiple CMIP5 (Coupled Model Intercomparison Project phase 5) future scenarios run with the CHIMERE chemistry transport model (CTM) are compared to historic simulations in order to study some of the drivers governing air pollution. Here, the focus is on regional climate, anthropogenic emissions and long-range transport. Two major subdomains are explored – the European region and the Mediterranean Basin – with both areas showing high sensitivity to climate change. The Mediterranean area is explored in the context of the ChArMEx (the Chemistry Aerosol Mediterranean Experiment) project, which examines the current and future meteorological and chemical conditions of the Mediterranean area. This climate impact study covers the period from 2031 to 2100 and considers possible future scenarios in comparison with 1976 to 2005 historic simulations using three Representative Concentration Pathways (RCPs; RCP2.6, RCP4.5 and RCP8.5). A detailed analysis of total PM10 (particulate matter with a diameter smaller that 10 µm) concentrations is carried out, including the evolution of PM10 and changes to its composition. The individual effects of meteorological conditions on PM10 components are explored in these scenarios in an effort to pinpoint the meteorological parameter(s) governing each component. The anthropogenic emission impact study covers the period from 2046 to 2055 using current legislation (CLE) and maximum feasible reduction (MFR) anthropogenic emissions for the year 2050 compared with historic simulations covering the period from 1996 to 2005 and utilizing CLE2010 emissions data. Long-range transport is explored by changing the boundary conditions in the chemistry transport model over the same period as the emission impact studies. Finally, a cumulative effect analysis of these drivers is performed, and the impact of each driver on PM10 and its components is estimated. The results show that regional climate change causes a decrease in the PM10 concentrations in our scenarios (in both the European and Mediterranean subdomains), as a result of a decrease in nitrate, sulfate, ammonium and dust atmospheric concentrations in most scenarios. On the contrary, BSOA (biogenic secondary organic aerosol) displays an important increase in all scenarios, showing more pronounced concentrations for the European subdomain compared with the Mediterranean region. Regarding the relationship of different meteorological parameters to concentrations of different species, nitrate and BSOA show a strong temperature dependence, whereas sulfate is most strongly correlated with relative humidity. The temperature-dependent behavior of BSOA changes when looking at the Mediterranean subdomain, where it displays more dependence on wind speed, due to the transported nature of BSOA existing in this subdomain. A cumulative look at all drivers shows that anthropogenic emission changes overshadow changes caused by climate and long-range transport for both of the subdomains explored, with the exception of dust particles for which long-range transport changes are more influential, especially in the Mediterranean Basin. For certain species (such as sulfates and BSOA), in most of the subdomains explored, the changes caused by anthropogenic emissions are (to a certain extent) reduced by the boundary conditions and regional climate changes