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Multi-year ACSM measurements at the central European research station Melpitz (Germany) - Part 1 : Instrument robustness, quality assurance, and impact of upper size cutoff diameter
No full textInternational audienceThe aerosol chemical speciation monitor (ACSM) is nowadays widely used to identify and quantify the main components of fine particles in ambient air. As such, its deployment at observatory platforms is fully incorporated within the European Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS). Regular intercomparisons are organized at the Aerosol Chemical Monitoring Calibration Center (ACMCC; part of the European Center for Aerosol Calibration, Paris, France) to ensure the consistency of the dataset, as well as instrumental performance and variability. However, in situ quality assurance remains a fundamental aspect of the instrument's stability. Here, we present and discuss the main outputs of long-term quality assurance efforts achieved for ACSM measurements at the research station Melpitz (Germany) since 2012 onwards. In order to validate the ACSM measurements over the years and to characterize seasonal variations, nitrate, sulfate, ammonium, organic, and particle mass concentrations were systematically compared against the collocated measurements of daily offline high-volume PM1 and PM2.5 filter samples and particle number size distribution (PNSD) measurements. Mass closure analysis was made by comparing the total particle mass (PM) concentration obtained by adding the mass concentration of equivalent black carbon (eBC) from the multi-angle absorption photometer (MAAP) to the ACSM chemical composition, to that of PM1 and PM2.5 during filter weighing, as well as to the derived mass concentration of PNSD. A combination of PM1 and PM2.5 filter samples helped identifying the critical importance of the upper size cutoff of the ACSM during such exercises. The ACSM–MAAP-derived mass concentrations systematically deviated from the PM1 mass when the mass concentration of the latter represented less than 60 % of PM2.5, which was linked to the transmission efficiency of the aerodynamic lenses of the ACSM. The best correlations are obtained for sulfate (slope =0.96; R2=0.77) and total PM (slope =1.02; R2=0.90). Although, sulfate did not exhibit a seasonal dependency, total PM mass concentration revealed a small seasonal variability linked to the increase in non-water-soluble fractions. The nitrate suffers from a loss of ammonium nitrate during filter collection, and the contribution of organo-nitrate compounds to the ACSM nitrate signal make it difficult to directly compare the two methods. The contribution of m∕z 44 (f44) to the total organic mass concentration was used to convert the ACSM organic mass (OM) to organic carbon (OC) by using a similar approach as for the aerosol mass spectrometer (AMS). The resulting estimated OC ACSM was compared with the measured OC PM1 (slope =0.74; R2=0.77), indicating that the f44 signal was relatively free of interferences during this period. The PM2.5 filter samples use for the ACSM data quality might suffer from a systematic bias due to a size truncation effect as well as to the presence of chemical species that cannot be detected by the ACSM in coarse mode (e.g., sodium nitrate and sodium sulfate). This may lead to a systematic underestimation of the ACSM particle mass concentration and/or a positive artifact that artificially decreases the discrepancies between the two methods. Consequently, ACSM data validation using PM2.5 filters has to be interpreted with extreme care. The particle mass closure with the PNSD was satisfying (slope =0.77; R2=0.90 over the entire period), with a slight overestimation of the mobility particle size spectrometer (MPSS)-derived mass concentration in winter. This seasonal variability was related to a change on the PNSD and a larger contribution of the supermicrometer particles in winter. This long-term analysis between the ACSM and other collocated instruments confirms the robustness of the ACSM and its suitability for long-term measurements. Particle mass closure with the PNSD is strongly recommended to ensure the stability of the ACSM. A near-real-time mass closure procedure within the entire ACTRIS–ACSM network certainly represents an optimal quality control and assurance of both warranting the quality assurance of the ACSM measurements as well as identifying cross-instrumental biases
Development of a generic zebrafish embryo PBPK model and application to the developmental toxicity assessment of valproic acid analogs
No full textInternational audienceIn order to better explain, predict, or extrapolate to humans the developmental toxicity effects of chemicals to zebrafish (Danio rerio) embryos, we developed a physiologically-based pharmacokinetic (PBPK) model designed to predict organ concentrations of neutral or ionizable chemicals, up to 120 h post-fertilization. Chemicals’ distribution is modeled in the cells, lysosomes, and mitochondria of ten organs of the embryo. The model’s partition coefficients are calculated with sub-models using physicochemical properties of the chemicals of interest. The model accounts for organ growth and changes in metabolic clearance with time. We compared ab initio model predictions to data obtained on culture medium and embryo concentrations of valproic acid (VPA) and nine analogs during continuous dosing under the OECD test guideline 236. We further improved the predictions by estimating metabolic clearance and partition coefficients from the data by Bayesian calibration. We also assessed the performance of the model at reproducing data published by Brox et al. (2016) on VPA and 16 other chemicals. We finally compared dose-response relationships calculated for mortality and malformations on the basis of predicted whole embryo concentrations versus those based on nominal water concentrations. The use of target organ concentrations substantially shifted the magnitude of dose-response parameters and the relative toxicity ranking of chemicals studied
Good and bad reasons : The Swiss cheese model and its critics
No full textInternational audienceThis article provides a historical and critical account of James Reason’s contribution to safety research with a focus on the Swiss cheese model (SCM), its developments and its critics. This article shows that the SCM is a product of specific historical circumstances, has been developed over a ten years period following several steps, and has benefited of the direct influence of John Wreathall. Reason took part in intense intellectual debates and publications in the 1980s during which many ideas circulated among researchers, featuring authors as influent as Donald Norman, Jens Rasmussen, Charles Perrow or Barry Turner. The 1980s and 1990s were highly productive from a safety research point of view (e.g. human error, incubation models, high reliability organisation, safety culture) and Reason has considerably influenced it with a rich production of models, based on both research and industrial projects. Historical perspectives offer interesting insights because they can question research, the conditions of its production, its relevance and, sometimes, its success, as for the SCM. But, because of this success, critics have vividly argued about some of the SCM limitations, including its simplistic vision of accidents and its degree of generality. Against these positions, the article develops a ‘critique of the criticism’, and the article concludes that the SCM remains a relevant model because of its systemic foundations and its sustained use in high-risk industries; despite of course, the need to keep imagining alternatives based on the mix of collective empirical, practical and graphical research which was in the SCM background
5G technology and health effects
No full textInternational audienceThis review* analyzed the results of in vivo and in vitro experiments from 94 scientific publications investigating exposure to the radiofrequencies used for 5G. Each study was characterized by type, biological material, outcome criteria, the configurations/ magnitude of exposure, and quality criteria. Relations between exposure and biological responses were observed in 80% of the in vivo and 58% of the in vitro studies
Comparison of tropospheric NO2 columns from MAX-DOAS retrievals and regional air quality model simulations
No full textInternational audienceAbstract. Multi-axis differential optical absorption spectroscopy (MAX-DOAS) tropospheric NO2 column retrievals from four European measurement stations are compared to simulations from five regional air quality models which contribute to the European regional ensemble forecasts and reanalyses of the operational Copernicus Atmosphere Monitoring Service (CAMS). Compared to other observational data usually applied for regional model evaluation, MAX-DOAS data are closer to the regional model data in terms of horizontal and vertical resolution, and multiple measurements are available during daylight, so that, for example, diurnal cycles of trace gases can be investigated. In general, there is good agreement between simulated and retrieved NO2 column values for individual MAX-DOAS measurements with correlations between 35 % and 70 % for individual models and 45 % to 75 % for the ensemble median for tropospheric NO2 vertical column densities (VCDs), indicating that emissions, transport and tropospheric chemistry of NOx are on average well simulated. However, large differences are found for individual pollution plumes observed by MAX-DOAS. Most of the models overestimate seasonal cycles for the majority of MAX-DOAS sites investigated. At the urban stations, weekly cycles are reproduced well, but the decrease towards the weekend is underestimated and diurnal cycles are overall not well represented. In particular, simulated morning rush hour peaks are not confirmed by MAX-DOAS retrievals, and models fail to reproduce observed changes in diurnal cycles for weekdays versus weekends. The results of this study show that future model development needs to concentrate on improving representation of diurnal cycles and associated temporal scalings
Evaluation of Inflammation by Cytokine Production Following Combined Exposure to Ultraviolet and Radiofrequency Radiation of Mobile Phones on 3D Reconstructed Human Skin In Vitro
No full textInternational audienceThe absorption of exposure to radiofrequency (RF) emitted by wireless devices leads to a high specific absorption rate in the skin. Ultraviolet (UV) radiation can induce several damages to the skin. The aim of this study was to examine whether combined, consecutive exposure to solar UV radiation and 1950 MHz RF exposure of third generation (3G) mobile system have any effect on inflammation processes in the skin. Under in vitro experiments, the inflammation process was examined by cytokines (IL-1α, IL-6, and IL-8) and MMP-1 enzyme secretion on 3D full thickness human skin model. The RF exposure was applied before or after UV irradiation, in order to study either the possible cooperative or protective effects of exposure to RF and UV. We did not find changes in cytokines due to exposure to RF alone. The RF exposure did not enhance the effects of UV radiation. There was a statistically not-significant decrease in cytokines when the skin tissues were pre-exposed to RF before being exposed to 4 standard erythemal dose (SED) UV compared to UV exposure alone. We found that RF exposure reduced the previously UV-treated MMP-1 enzyme concentration. This study might support the evaluation of the effects on the skin exposed to microwave radiation of 5G mobile technology
Chemical characterization of SOA from diesel and gasoline vehicles with untargeted approaches
No full textInternational audienceRecent studies have shown that the PM emissions of modern cars equipped with the newest after-treatment technologies are mainly related to the production of secondary organic aerosols (SOA) especially in the case of gasoline vehicles. The objective of this work is to identify specific molecular markers or chemical patterns that can be further used in PM source apportionment studies to discriminate SOA from diesel and gasoline vehicles. Experiments were performed on a chassis dynamometer with a gasoline and diesel Euro 5 vehicles. Exhaust emissions were diluted before introduction into a potential aerosol mass (PAM) oxidation flow reactor (OFR) for aging and SOA formation. About 50 filter samples were collected upstream and downstream the PAM-OFR and analyzed using innovative non-targeted approaches with high-resolution mass spectrometry coupled to gas or liquid chromatography. The data treatment and statistical analysis will allow to highlight features or chemical patterns specific of gasoline and diesel SOA
Évaluation de l’exposition des populations aux pyréthrinoïdes : vision croisée des démarches de caractérisation
No full textInternational audienceLe croisement des deux approches - mesure biologique et modélisation - doit être mené conjointement afin de permettre l’amélioration de l’efficacité des outils d’aide à la décision pour réduire les expositions
Applicabilité de la technique de "screening non ciblé" pour la surveillance prospective. Rapport final
No full textCe rapport présente les actions menées dans le cadre du Réseau français de Surveillance Prospective concernant les approches de screening non ciblé ou NTS. L’objectif de cette étude était d’évaluer, sur des échantillons réels et un panel d’échantillons représentatifs, l’applicabilité de ces approches(par le traitement suspect des données) pour acquérir de nouvelles connaissances sur la présence de micropolluants organiques dans des cours d’eau. Le premier objectif est méthodologique : les approches, mises en œuvre par 3 laboratoires de recherche, sont comparées sur le même jeu d’échantillons issus de 20 stations de surveillance d’eau de surface, via deux approches d’échantillonnage : ponctuel (prélèvement d’eau et extraction sur phase solide) et intégratif (échantillonneurs intégratifs passifs de type POCIS-HLB). Sur le plan méthodologique et de l’assurance qualité, l’action a mis en évidence des besoins métrologiques indispensable pour une mise en œuvre fiable de ces techniques de screening non ciblé (blanc, contrôles, traceurs). La comparaison des résultats obtenus par les 3 laboratoires a permis l’identification des critères clefs permettant d’assurer la validité et la comparabilité des donnéesproduites.La complémentarité de différentes approches de traitements des données brutes et des différentes typologies de bases de données utilisables pour identifier les composés d’intérêt est mise en évidence. Cette étude montre le compromis nécessaire entre le temps de traitement et le degré de confiance dans les résultats obtenus. La possibilité d’utiliser de manière successive ces différentes approches est évaluée et permet d’optimiser les traitements tout en amélioration la confiance dans les résultats obtenus. L’utilisation à visée quantitative des analyses NTS est étudiée et montre la faisabilitéd’obtenir une estimation de la concentration pour des composés d’intérêt.D’un point de vue opérationnel, afin de faciliter la compréhension des rendus de résultats et d’intégrer au mieux l’incertitude associée aux différentes voies d’identification d’une substance, des schémas de décision sont proposés et éprouvés, permettant une communication transparente entre producteurs de données et utilisateurs.Le second objectif vise l’acquisition de connaissances nouvelles. L’étude a montré qu’il était possible, de mettre en évidence jusqu’à 80% de molécules supplémentaires par rapport aux listes de substances réglementaires ou régulièrement surveillées. La réutilisation des données acquises a été éprouvée et permet d’améliorer, au fur et à mesure de l’acquisition de nouvelles informations, les connaissances. Cette approche permet donc d’améliorer la surveillance en l’orientant vers des molécules effectivement présentes
Les politiques d’ouverture à la société instruments du changement des relations entre associations et instituts d’expertise dans le domaine de la santé environnement en France?
No full textInternational audienceThis paper reviews the evolution of alliances between advocacy groups and associations, on the one hand, and scientific institutes and agencies, on the other, in the field of environmental health in France from 1990 until now. The article describes how these public institutions of expertise have adapted to a new context, placing their collaborations with associations at the heart of their institutional agendas. By retracing the history of opening policies to society, we show the stakes, the different groups of actors involved, as well as the norms and procedures by which science reaches out to society. Finally, we highlight the main limitations of these policies and outline opportunities for associations and expertise organizations to continue this change