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La surveillance de risques émergents à partir d’algorithmes: Nécessité d’une participation active de la société
No full textInternational audienceLe développement de notre société et les changements climatiques font apparaître des risques nouveaux qu'il faut pouvoir anticiper pour éviter des dommages sanitaires, environnementaux et financiers. Ce chapitre traite des différentes composantes du risque à prendre en compte dans l'anticipation. Les algorithmes d'identification, de traitement et de surveillance automatique de ces composantes sont, dans un second point, décrits en détail. Les limites des différents algorithmes sont évoqués dans une troisième partie, faisant apparaître le réel besoin d'une complémentarité entre algorithmes et implication sociétale dans l'exercice d'identification et surveillance des risques émergents
Some fundamental combustion properties of “cryogenic” premixed hydrogen air flames
No full textInternational audienceBecause of the emergence of the U.E. “green deal” and because of the significant implication of national and regional authorities throughout Europe, the “hydrogen” economy is emerging. And with it, numerous questions and experimentations. One of them, perhaps a key point, is the storage and transport of hydrogen. Liquid hydrogen in cryogenic conditions is a possibility already used in the space industry but under a lot of constrains. What may be acceptable in a well-controlled and restrained domain may not be realistic in a wider application, closer to the public. Safety should be ensured and there is a need for a better knowledge of the flammable and ignition properties of the “cold” hydrogen mixtures following a cryogenic spillage for instance to select adequate ATEX equipment. The purpose of PRESLHY project [4] is to investigate the ignition, fire and explosion characteristics of cryogenic hydrogen spillages and to propose safety engineering methods. The present work is part of it and addresses the measurement of the laminar burning velocity (Sl), flammability limits (FL), minimum ignition energy (MIE)… of hydrogen air mixtures at atmospheric pressure but down to -150°C. To do this, a special burner was designed with details given inside this paper together with the experimental results. It is found that the FL domain is reduced when the temperature drops, that MIE increases slightly and Sl decreases
Preliminary risk assessment (PRA) for tests planned in a pilot salt cavern hydrogen storage in the frame of the French project STOPIL-H2
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Seasonality of the particle number concentration and size distribution: a global analysis retrieved from the network of Global Atmosphere Watch (GAW) near-surface observatories
No full textInternational audienceAerosol particles are a complex component of the atmospheric system which influence climate directly by interacting with solar radiation, and indirectly by contributing to cloud formation. The variety of their sources, as well as the multiple transformations they may undergo during their transport (including wet and dry deposition), result in significant spatial and temporal variability of their properties. Documenting this variability is essential to provide a proper representation of aerosols and cloud condensation nuclei (CCN) in climate models. Using measurements conducted in 2016 or 2017 at 62 ground-based stations around the world, this study provides the most up-to-date picture of the spatial distribution of particle number concentration (Ntot) and number size distribution (PNSD, from 39 sites). A sensitivity study was first performed to assess the impact of data availability on Ntot's annual and seasonal statistics, as well as on the analysis of its diel cycle. Thresholds of 50 % and 60 % were set at the seasonal and annual scale, respectively, for the study of the corresponding statistics, and a slightly higher coverage (75 %) was required to document the diel cycle.Although some observations are common to a majority of sites, the variety of environments characterizing these stations made it possible to highlight contrasting findings, which, among other factors, seem to be significantly related to the level of anthropogenic influence. The concentrations measured at polar sites are the lowest (∼ 102 cm−3) and show a clear seasonality, which is also visible in the shape of the PNSD, while diel cycles are in general less evident, due notably to the absence of a regular day–night cycle in some seasons. In contrast, the concentrations characteristic of urban environments are the highest (∼ 103–104 cm−3) and do not show pronounced seasonal variations, whereas diel cycles tend to be very regular over the year at these stations. The remaining sites, including mountain and non-urban continental and coastal stations, do not exhibit as obvious common behaviour as polar and urban sites and display, on average, intermediate Ntot (∼ 102–103 cm−3). Particle concentrations measured at mountain sites, however, are generally lower compared to nearby lowland sites, and tend to exhibit somewhat more pronounced seasonal variations as a likely result of the strong impact of the atmospheric boundary layer (ABL) influence in connection with the topography of the sites. ABL dynamics also likely contribute to the diel cycle of Ntot observed at these stations. Based on available PNSD measurements, CCN-sized particles (considered here as either >50 nm or >100 nm) can represent from a few percent to almost all of Ntot, corresponding to seasonal medians on the order of ∼ 10 to 1000 cm−3, with seasonal patterns and a hierarchy of the site types broadly similar to those observed for Ntot.Overall, this work illustrates the importance of in situ measurements, in particular for the study of aerosol physical properties, and thus strongly supports the development of a broad global network of near surface observatories to increase and homogenize the spatial coverage of the measurements, and guarantee as well data availability and quality. The results of this study also provide a valuable, freely available and easy to use support for model comparison and validation, with the ultimate goal of contributing to improvement of the representation of aerosol–cloud interactions in models, and, therefore, of the evaluation of the impact of aerosol particles on climate
Exposure to nanoparticles in thermal spraying - Vigilance towards the operator and the outside environment
No full textInternational audienceThe previous survey of the French CaRPE project has shown a lack of information and showed the interest to assess the residual exposure to these particles. This paper presents the results of various sampling operations and emission analyses of plasma spraying equipment. For this purpose, different areas have been targeted, such as at the level of the emissions channeled upstream and downstream of the filtration system, at the workstation level as well as fugitive emissions. Various measurements were carried out: real-time particle size distribution, mass concentration of total suspended dust, heavy metals, sampling characterization by EDX/ MET, etc. The metallic aerosol is mainly composed of nanometric structures. The number concentration is particularly high (between 108 and 109 particles/cm3) downstream the filtration system. Measurements upstream and downstream of the filtration system have made it possible to determine its efficiency, which is greater than 90%. The mass concentration downstream of the filter is ~2.6 mg/m3 while the number concentration remains above 106 particles/cm3. Some recommendations were then derived. Very great vigilance is therefore recommended in order to protect the operator, since we must remember that we are in the presence of a very high concentration of metallic and nanostructured particles
Modeling acetylcholine esterase inhibition resulting from exposure to a mixture of atrazine and chlorpyrifos using a physiologically-based kinetic model in fish
No full textInternational audienceAquatic organisms are exposed to mixtures of chemicals that may interact. Mixtures of atrazine (ATR) and chlorpyrifos (CPF) may elicit synergic effects on the permanent inhibition of acetylcholinesterase (AChE) in certain aquatic organisms, causing severe damage. Mechanistic mathematical models of toxicokinetics and toxicodynamics (TD) may be used to better characterize and understand the interactions of these two chemicals. In this study, a previously published generic physiologically-based toxicokinetic (PBTK) model for fish was adapted to ATR and CPF. A sub-model of the kinetics of one of the main metabolites of CPF, chlorpyrifos-oxon (CPF-oxon), was included, as well as a TD model. Inhibition of two esterases, AChE and carboxylesterase, by ATR, CPF and CPF-oxon, was modeled using TD modeling of quantities of total and inactive esterases. Specific attention was given to the parameterization and calibration of the model to accurately predict the concentration and effects observed in the fish using Bayesian inference and published data from fathead minnow (Pimephales promelas), zebrafish (Dunn) rerio) and common carp (Cyprinus carpio L.). A PBTK-TD for mixtures was used to predict dose-response relationships for comparison with available adult fish data. Synergistic effects of a joint exposure to ATR and CPU could not be demonstrated in adult fish
Analysis of Faults' Effect on the Stability of Surface Lignite Mining Areas Using the Distinct Element Method
No full textInternational audienceMining operations can drastically affect the stability of nearby areas. A representative case for this has been the Mavropigi mine, a part of an open-pit lignite mining complex in northwestern Greece. Mavropigi is a vast excavation that has reached 150 m depth and has posed severe challenges and stability issues that caused problems in the area. In 2010, noteworthy surface tension cracks appeared near the excavation, leading to extensive monitoring and countermeasures, while various studies were conducted. The present work aims to revisit the case study of Mavropigi from a different than the previous perspectives. Previous studies were based only on continuum approaches, thus understating or ignoring the effect of discontinuities. Nevertheless, the area has an intense tectonic past and faults that interact with soil movements. In this work, advanced, discontinuous numerical modelling through the distinct element method was used to understand better the role of slope-fault interaction in the case study of Mavropigi and assess the faults' effect on the area's response. The results emphasised the influence of faults on ground movements. The fault's existence increases the impact of the mine operations on the surrounding area significantly and intensifies the possibility of structural damage in nearby constructions. The analysis confirms that the open-pit mine's effect on the surrounding area can be amplified under complex geological conditions, in this case, the presence of faults nearly parallel to the slope inclination
Application in a biomonitoring context of three-spined stickleback immunomarker reference ranges
No full textInternational audienceThe relevance of a biomarker for biomonitoring programs was influenced both by the knowledge on biomarker natural inter-individual and site variabilities and by the sensitivity of the biomarker towards environmental perturbations. To minimize data misinterpretation, robustness reference values for biomarkers were important in biomonitoring programs. Specific three-spined stickleback, Gasterosteus aculeatus, immune reference ranges for field studies had been determined based on laboratory data and one reference station (Contentieuse river at Houdancourt). In this study, data obtained in one uncontaminated and three contaminated sites were compared to these reference ranges as a validation step before considering them for larger scale biomonitoring programs. When the field reference range were compared to data from the uncontaminated station (Béronelle), only few deviations were shown. In this way, data coming from uncontaminated station (Béronelle) was integrated in the field reference ranges to improve the evaluation of site variability. The new field reference ranges provided better discrimination of sites and spanned a larger range of fish lengths than the initial reference ranges. Furthermore, the results suggest lysosomal presence during several months and phagocytosis capacity in autumn may be the most relevant immunomarkers towards identifying contaminated sites. In the future, combining this reference value approach with active biomonitoring could facilitate the obtention of data in multiple stream conditions
Alternatives potentielles au formaldéhyde en pisciculture: Avis de l’Anses. Rapport d’expertise collective
No full textLe formaldéhyde a été classé en 2004 par le Centre international de recherche sur le cancer (CIRC) dans le groupe 1 des cancérogènes avérés pour l’espèce humaine et cette classification a été confirmée en octobre 2009 sur la base de l’induction de tumeurs du nasopharynx et de leucémies. Au niveau européen, une évolution du classement de cancérogène de catégorie 2 à cancérogène de catégorie 1B a été adoptée par le règlement (UE) n° 605/2014 de la Commission du 5 juin 2014 modifiant aux fins de son adaptation au progrès technique le règlement CLP.En France, l’arrêté du 13 Juillet 2006 a ajouté « les travaux exposant au formaldéhyde » à la liste des substances, mélanges et procédés cancérogènes au sens de l’article R. 4412-60 du code du travail. La recherche de substitution des agents cancérogènes, mutagènes ou toxiques pour la reproduction (CMR) de catégorie 1A ou 1B est une obligation qui s’impose à l’employeur. Elle est énoncée dans les principes généraux de prévention à l’article L. 4121-2 du code du travail et est renforcée à l'article R. 4412-66. Ainsi, l’employeur doit pouvoir justifier des démarches fructueuses ou infructueuses qu’il a entreprises en vue de la substitution de tous les agents ou procédés CMR de catégories 1A et 1B inventoriés sur le lieu de travail. Le résultat de ces investigations doit, notamment, figurer dans le document unique d’évaluation des risques. Seul un argumentaire technique fondé est recevable pour justifier de la non-substitution d’un agent ou procédé CMR de catégorie 1A ou 1B par un agent ou un procédé non ou moins dangereux.Lorsque la substitution s’avère impossible, l’employeur doit mettre en œuvre tous les moyens permettant de réduire l’exposition en utilisant des mesures de prévention et de protection adaptées (système clos, autres moyens de protection collective, puis moyens de protection individuelle mais également formation et information du personnel, surveillance médicale).Compte-tenu de ces nouvelles informations sur les propriétés de danger du formaldéhyde et la priorité à la substitution en matière de gestion des risques professionnels, l’Anses a été saisie, en date du 09 octobre 2014, de manière conjointe par la direction générale du travail (DGT), la direction générale de la santé (DGS), la direction générale de la consommation, de la concurrence et de la répression des fraudes (DGCCRF) et la direction générale de la prévention des risques (DGPR), pour une « Demande d’avis relatif à l’utilisation de substituts au formaldéhyde dans différents secteurs d’activité ». Il est demandé à l’Anses d’éclairer les pouvoirs publics : sur l’intérêt du formaldéhyde par rapport aux autres substituts pour le diagnostic en matière d’anatomie et cytologie pathologiques dans les situations de routine et dans des situations particulières pour lesquelles le formaldéhyde reste indispensable et qu’il conviendra de préciser ; sur l’intérêt du formaldéhyde par rapport aux autres substituts pour les actes de thanatopraxie, avec un état des lieux sur les travaux en cours au niveau européen dans le cadre du règlement biocide en matière d’évaluation de la substance active formaldéhyde (TP 2, 3, 20 et 22). Par ailleurs, les directions souhaiteraient disposer, dans le cadre des travaux menés sur les substituts au formaldéhyde en anatomie et en cytologiepathologique, d’une analyse sur les possibilités d’utilisation de ces substituts dans certains types de produits biocides, et notamment en TP 22, et sur les conséquences éventuelles en termes de toxicité et d’écotoxicité ; sur l’intérêt du formaldéhyde par rapport aux autres substituts pour l’utilisation en alimentation animale en tant qu’auxiliaire technologique pour la protection contre la dégradation ruminale, en tant qu’additif conservateur, en tant qu’additif d’ensilage et en tant qu’additif visant à limiter ou à réduire la charge microbienne des organismes pathogènes présents dans les aliments des animaux ; sur l’intérêt du formaldéhyde par rapport aux autres substituts pour l’utilisation en alimentation humaine en tant qu’auxiliaire technologique pour d’une part la fabrication de certains alginates et d’autre part l’utilisation comme bactériostatique dans la filière du secteur du sucre ;Les utilisations du formaldéhyde dans les 4 secteurs d’activité précédemment décrits s’inscrivent dans un contexte où il existe, d’une part un référentiel international ou une autorisation de mise sur le marché qui a été délivrée par les autorités européennes ou françaises légitimant ces usages du formaldéhyde et d’autre part, les obligations du code du travail qui, suite à la classification du formaldéhyde, indiquent que la première des actions à mener est la substitution.Les ministères de tutelles demandent à l’Anses de justifier l’intérêt du formaldéhyde par rapport aux autres substituts dans ces secteurs d’activités. Les experts de l’Anses estiment que la question posée revient à justifier l’utilisation d’un cancérogène de catégorie 1B par rapport à des substituts potentiellement moins dangereux. Les experts préfèrent se poser la question dans le sens inverse en identifiant des substituts moins dangereux capables de substituer la substance cancérogène dans les 4 secteurs d’activités. Le formaldéhyde est également utilisé en pisciculture. L’inspection des élevages piscicoles menée par les agents du Ministère de l’agriculture et de l’alimentation en vue de l’obtention de leur agrément sanitaire, a révélé l’utilisation de formaldéhyde dans les bassins d’élevage. Cetteutilisation est destinée au traitement des bassins en présence des poissons en usage préventif ou curatif contre les ectoparasitoses (costiase notamment). Le ministère de l’agriculture a développé un plan d’action pour le développement de la filière aquacole et des travaux sont menés pour améliorer la disponibilité des médicaments vétérinaires dans cette filière. L’absence de médicaments vétérinaires disponibles pour le traitement antiparasitaire des poissons a été soulevée dans le cadre de ces travaux. La Direction générale de l’alimentation (DGAL) aégalement sollicité l’Agence nationale du médicament vétérinaire (ANMV) au sein de l’Anses pour évaluer les possibilités de recours à l’importation d’un médicament vétérinaire à base de formaldéhyde autorisé en Espagne.Les experts de l’Anses ont développé une méthode de travail afin de pouvoir comparer et évaluer des substituts à une substance chimique dangereuse en s’appuyant sur une revue de la littérature. La description de cette méthode fait l’objet d’un rapport de l’Anses intitulé « Document méthodologique de comparaison des alternatives à une substance chimique » (Anses 2018). La méthode a été appliquée aux substituts identifiés dans les secteurs d’activité ciblés dans lasaisine et dans l’auto-saisine.Le présent avis détaille la partie de l’auto-saisine 2016-SA-022 relative à l’application de la méthode aux alternatives potentielles au formaldéhyde dans le secteur de la pisciculture.[Saisine liée n° 2014-SA-0236
Cancer risk from chronic exposures to chemicals and radiation: a comparison of the toxicological reference value with the radiation detriment
No full textInternational audienceThis article aims at comparing reference methods for the assessment of cancer risk from exposure to genotoxic carcinogen chemical substances and to ionizing radiation. For chemicals, cancer potency is expressed as a toxicological reference value (TRV) based on the most sensitive type of cancer generally observed in animal experiment of oral or inhalation exposure. A dose-response curve is established by modelling experimental data adjusted to apply to human exposure. This leads to a point of departure from which the TRV is derived as the slope of a linear extrapolation to zero dose. Human lifetime cancer risk can then be assessed as the product of dose by TRV and it is generally considered to be acceptable below 10-5 for public in normal situation. Radiation exposure is assessed as effective dose corresponding to a weighted average of energy deposition in body organs. Cancer risk models were derived from the epidemiological follow-up of atomic bombing survivors. Considering a linear-no-threshold dose-risk relationship and average baseline risks, lifetime nominal risk coefficients were established for 13 types of cancers. Those are adjusted according to the severity of each cancer type and combined into an overall indicator denominated radiation detriment. Exposure to radiation is subject to dose limits proscribing unacceptable health detriment. The differences between chemical and radiological cancer risk assessments are discussed and concern data sources, extrapolation to low doses, definition of dose, considered health effects and level of conservatism. Despite these differences, opportunities exist to bring closer the two types of risk assessment