Contexte. La population agricole française, dans son ensemble, présente un plus faible risque de Cancer BronchoPulmonaire (CBP) par rapport à la population générale. Ce constat, retrouvé au niveau international, s’explique au moins en partie par un tabagisme plus faible notamment chez les plus âgés et chez les femmes ; un effet « protecteur » des endotoxines est également suspecté. Néanmoins le milieu professionnel agricole peut exposer à de nombreux cancérogènes pulmonaires avérés ou suspectés ; malgré cela, à l’exception de certains secteurs d’élevage, il n’existe que très peu de données sur les associations entre expositions ou situations de travail précises en milieu agricole et le risque de CBP. Objectifs. Le premier objectif de ce travail de thèse était d’étudier les associations, au sein de la cohorte AGRICAN (AGRIculture et CANcer), entre (1) CBP et exposition aux activités et tâches de cultures ; (2) CBP et utilisation de pesticides arsenicaux et herbicides dinitroanilines, et de mettre à profit le nombre important de sujets inclus et de cas de CBP pour réaliser ces analyses par sous-type histologique. Le deuxième objectif était d’initier un projet de métrologie de divers aérocontaminants en milieu professionnel agricole. Méthodes. Les analyses ont été menées en utilisant les données de l’étudeAGRICAN et de la matrice culture-exposition aux pesticides PESTIMAT. Nous avons utilisé un modèle de Cox, ajusté sur le sexe, le tabagisme, les élevages bovin et équin. Le projet métrologique AirExpA s’est limité à la Normandie, avec mesures personnelles des poussières totales (en temps réel), endotoxines et 38 mycotoxines (en cumulé), en élevage bovin, lors des foins et des moissons de blé/orge et pois fourrager/féverole. Résultats et discussion. Nous avons retrouvé une association inverse entre l’activité de culture de maïs et le risque de CBP, une association positive entre adénocarcinomes et viticulture, ainsi qu’entre carcinomes à petites cellules et culture de pois fourragers/féveroles. Les éléments de plausibilité d’un lien entre ces secteurs d’activité et le risque de CBP sont encore des hypothèses : la culture de maïs, par le stockage du grain, pourrait exposer aux endotoxines ; à l’inverse, la récolte de pois fourragers a été décrite comme empoussiérante, mais cet élément doit être confirmé par une caractérisation des poussières. Nous n’avons pas retrouvé d’association entre utilisation de pesticides arsenicaux, ni de dinitroanilines, et risque de CBP ; cependant les analyses stratifiées sur le sexe et le statut tabagique, montraient des associations positives chez les non-fumeurs et chez les femmes (en particulier pour les adénocarcinomes). Enfin, le projet AirExpA a permis de documenter un gradient d’exposition aux poussières et endotoxines en fonction de différentes tâches en élevage bovin, et une exposition plus modérée mais réelle, aux endotoxines, lors des activités de culture. Les analyses de mycotoxines sont toutes revenues inférieures aux limites de quantification. L’analyse des pics d’exposition, l’étude d’autres aérocontaminants et d’autres secteurs agricoles, sont des perspectives de ce projet. Conclusion. Notre travail soulève de nouvelles questions de recherche quant à des associations possibles entre certaines expositions professionnelles en milieu agricole (cultures et tâches, utilisation de certains pesticides) et risque de CBP, et contribue à une meilleure connaissance des expositions professionnelles des agriculteurs aux aérocontaminants. / Background. Farmers are at lower risk of lung cancer, compared to the general population, at least partly because of a reduced rate of smoking among the elderly and women. A “protective” effect of endotoxins has also been hypothesized. Even though some of the occupational exposures occurring during farming-related activities are well-known or suspected lung carcinogens, there is scarce data in the literature, about the associations between specific occupational exposures or tasks in farming, and the risk of lung cancer. Objectives.The first aim was to analyse, in the AGRICAN cohort, the associations between lung cancer and (1) occupational exposure to various crops and related tasks; (2) arsenical pesticides and dinitroaniline herbicides use in farming. We also aimed at stratifying our analysis by histological subtypes of lung cancer. The second aim was to initiate a metrological project, to assess farmers’ occupational exposure to various airborne pollutants, in relation with the risk of lung cancer. Methods. We used the data from the French AGRIculture and CANcer cohort (AGRICAN) and from the PESTIcide MATrix project (PESTIMAT), to assess the associations between occupational farming exposures and lung cancer. A Cox model was performed, with adjustment on gender, smoking intensity, cattle and horses breeding. Our metrological project AirExpA was first launched in Normandy and focused on a few exposures – total dusts in real-time ; endotoxins and 38 mycotoxins, cumulative – in cattle breeding, wheat/barley and peas harvesting, and haymaking. Results and discussion. We reported a negative association between lung cancer and corn growing, and positive associations between (1) vineyard growing and adenocarcinoma; (2) peas growing and small cell lung cancer. Corn growing, especially grain handling, might expose to significant levels of endotoxins, thus explaining the inverse association. Peas growing, especially harvesting, is reportedly a dusty task; the AirExpA project will enable us to better characterize the dusts. We found no association between arsenicals use and lung cancer, nor with dinitroaniline herbicides use. However, stratifying on gender and smoking status showed positive associations among women and never-smokers, especially for adenocarcinomas. The AirExpA project showed dust and endotoxins exposure gradients in cattle breeding, depending on the task, and a mild but real exposure to endotoxins in various tasks in crop growing. All samples for mycotoxins were below the limit of quantification. Analysing exposure peaks, extending the project to other breedings/crops and air pollutants are among the perspectives. Conclusion. Our results raise new research questions about possible associations between occupational agricultural exposures and lung cancer, and contribute to a better knowledge and understanding of farmers’ occupational exposure to air pollutants.

Over the course of our lives we are exposed to airborne particulate matter in the workplace, home, and environment that results in the deposition of millions of particles in the lung. These exposures may result in disease if they are significant enough. The potential for harmful exposure depends in part on the dust's biodurability and the bioavailability of harmful constituents derived from the particles. A mixed flow reactor was used to evaluate two applications of geochemical methods to characterize the behavior of inhaled particles in the body. Dissolution rates of a well-characterized sample of powdered talc were measured in solvents that mimic fluids found in the human lung. These studies showed that variation of solvent chemistry, including the addition of organic chelators and proteins at intercellular fluid concentrations, does not markedly affect the measured dissolution rate of talc at 37 degrees Celcius and the data further indicate that the dissolution mechanism for talc in aqueous solutions is independent of pH over a range of pH from 2 to 8. The dissolution rate, determined by measuring the silicon release rate per unit surface area of talc is 1.4 (+/- 1.0) x 10-11 mol Si/(m2 -sec). A geometric shrinking particle model using this dissolution rate predicts an estimated lifetime (upper limit) of approximately 8 years for a 1 micron talc particle under pulmonary conditions. Talc dissolves considerably faster than quartz, but slower than chrysotile and olivine in the body. These data can be used to place constraints on the role of particle dissolution in the disease models associated with airborne respirable particulate matter. Secondly, the bioavailability of As and Cr was determined from a sample of coal fly ash from an eastern U.S. power plant. The time-release profiles of As and Cr were determined for these materials in physiologically-based solvents and incorporated into a toxicokinetic model to predict the exposure potential to As and Cr from occupational exposures to the coal fly ash. Predicted occupational exposure contributions from the ash relative to total environmental exposures were insignificant. The exposure predicted from the geochemical approach was compared with results observed in a cohort occupationally exposed to coal fly ash and found to be within one order of magnitude of the response of the occupational cohort. These results support the application of geochemical techniques to evaluate exposures to complex respirable materials. / Ph. D.

No description available.

The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission provides unique measurements of vertical profiles of aerosols and clouds and their properties during day and night-time over all types of surfaces. This information has the potential to significantly improve our understanding of the properties and effects of aerosol and clouds. This dissertation presents the results of a comprehensive analysis of CALIPSO lidar (version 2 and version 3.01) data in conjunction with A-Train satellite and ground-based observations aimed at characterizing mineral aerosol in East Asia and other major dust sources. The specific objectives were to characterize the spatial distribution and properties of atmospheric dust in the dust source regions using new CALIOP (version 3.01) data in conjunction with satellite MODIS, OMI, and CloudSat data and ground-based meteorological and lidar data; investigate changes in the vertical distribution and properties of dust during mid- and long-range transport; perform a modeling of the optical properties of nonspherical dust particles, and assess the radiative forcing and heating/cooling rates of atmospheric dust by performing radiative transfer modeling constrained by satellite data in major dust source regions.

La qualité de l’air des environnements intérieurs est essentielle pour la santé. Le manque de renouvellement d’air et l’humidité dans les habitats favorise la prolifération microbienne. Les effets sur la santé sont multiples et souvent associés à des maladies chroniques respiratoires, tel que l’asthme. Ces effets sont plus ou moins graves selon le niveau d’exposition et la vulnérabilité des occupants et le rôle des moisissures est pointé. Cependant, le manque d’outils valides permettant d’évaluer quantitativement l’exposition aux bactéries environnementales constitue une des principales difficultés pour mieux appréhender leur impact sur la santé humaine. Un protocole expérimental basé sur les techniques culturales a été développé et testé au laboratoire pour mesurer la survie des bactéries dans des poussières domestiques collectées au sol. L’analyse de ces poussières a permis de déterminer le temps de survie des bactéries testées. Cependant, les méthodes culturales actuelles sont limitées et n’apportent pas assez d’informations sur la composition de la flore bactérienne dans l’habitat. L’utilisation des méthodes moléculaires, tel que le séquençage haut débit, est nécessaire pour y remédier. Par ailleurs, les poussières domestiques pourraient constituer un substrat intégrateur de l’exposition chronique des occupants. Outre le développement, la standardisation, et la validation d’outils de mesure, une approche globale de sensibilisation et de prévention du risque d’exposition aux contaminants des environnements intérieurs est recommandée, en particulier chez les populations vulnérables. / Indoor air quality is essential for health. Lack of ventilation and presence of humidity in habitats promotes microbial growth. The health effects are multiple and often associated with chronic respiratory diseases, such as asthma. These effects are more or less serious depending on the level of exposure and the vulnerability of occupants and the role of mold is pointed out. However, the lack of valid tools for quantitatively assessing exposure to environmental bacteria is one of the main difficulties in better understanding their impact on human health. An experimental protocol based on cultural techniques was developed and tested in the laboratory to measure the survival of bacteria in domestic dust collected on the ground. The analysis of these dusts made it possible to determine the survival time of the bacteria tested. However, current culture methods are limited and do not provide enough information on the composition of the bacterial flora in the habitat. The use of molecular methods, such as high throughput sequencing, is needed to address this. In addition, domestic dust could be an integrating substrate for chronic occupant exposure. In addition to the development, standardization, and validation of measurement tools, a comprehensive approach to raising awareness and preventing the risk of indoor exposure to contaminants is recommended, particularly for vulnerable populations.

Thesis (Ph.D. (Mining Engineering))--University of the Witwatersrand, Faculty of Engineering,1992.

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Master of Science in Engineering / Regulation 10.24 of the Minerals Act (1991) of the Republic of South Africa is applied for the purpose of preventing the development and propagation of coal-dust explosions in underground coal mines. ( Abbreviation abstract ) / AC2017

Mineral dust aerosols play an important role in atmospheric chemistry through photolysis and heterogeneous uptake. Both mechanisms strongly depend on the size and composition of mineral dust. Because of the complex nature of dust, chemistry modeling commonly relies on simplified assumptions about the properties of dust particles relevant to physiochemical processes. The goal of this thesis is to investigate the impact of size-resolved composition of dust aerosols on atmospheric photochemistry. The relative importance of dust characteristics in photolysis and heterogeneous loss and the relative roles of the two mechanisms on atmospheric photochemistry are investigated. A new block of spectral aerosol optical properties was developed and incorporated into the tropospheric ultraviolet and visible radiation transfer code in order to calculate spectral actinic fluxes and photolysis rates, J-values. The Fuchs-Sutugin approximation was employed to compute mass transfer from gas to dust mineral species and heterogeneous loss rate, kloss,j. The J-values and kloss,j were incorporated into a one-dimensional photochemistry model to simulate the diurnal cycle of a vertical profile of photochemical species. Several cases of dust loading were considered in the clean and polluted marine environments. A size-resolved mineralogical composition was constructed by selecting a range of the mass fraction of the three main mineral species such as iron oxide-containing clay minerals, carbonate-containing species, and quartz. This work demonstrates that differences in microphysical and chemical properties of mineral dust lead to the important changes in spectral optical properties, J-values, and kloss,j. It also shows that non-linear relationships of photochemical species with two mechanisms result in various changes in the photochemical oxidant fields and that the most important factor controlling the photochemistry field is the dust size distribution, followed by the amount of mineral species with high uptake coefficients and the amount of iron oxide-clay aggregates. This work demonstrates that accounting for regional differences in microphysical and chemical properties of mineral dust will improve the assessment of the impact of mineral dust on tropospheric photochemistry. In addition, it suggests that the size and composition of mineral dust will lead to a deeper understanding of the impact of mineral dust on the global climate system.

Thesis (MSc (Earth Sciences))--Stellenbosch University, 2008. / This study aims to provide a practical tool for the prediction and management of dust generated by the activities of an opencast mining operation. The study was conducted on opencast gypsum mines in the semi-arid environment of the Bushmanland, 90 km north of Loeriesfontein in the Northern Cape Province from April 2000 to October 2007. The vertical and horizontal components of wind transported sediment were sampled and a dust settling model was designed to predict the settling pattern of dust generated by opencast mining operations. The model was applied to soil samples collected from an area surrounding a mine. The influence sphere of the mining operation was predicted by the application of the model and then mapped. Once the influence sphere is mapped, the dust influence can be managed with the aid of an onsite weather station. By further applying the predictions based on climatic data, the influence sphere can be modelled. The model is not only applicable to the planning phase of an opencast mine to plan the position of dust sensitive areas like the living quarters, office buildings and workshops etc., but also to indicate the historical impact that a mining operation had once a quarry on an active mine is worked out and rehabilitated or a mine is closed. The model application can also aid with the explanation and visual or graphic representation of the predicted impact of planned mining operations on communities or neighbouring activities to them and thus avoid later penalties.

Cette thèse vise à restituer l'histoire de la mousson africaine au cours du Quaternaire, et à en déterminer ses influences sur les variations des apports sédimentaires du Nil et des déserts d’Afrique du nord. Deux sites de la Méditerranée orientale ont alors été étudiés (la carotte MD90-964 dans la partie orientale du bassin Levantin et le Site ODP 964 dans la Mer ionienne). Sur la base des analyses de la minéralogie des argiles, de la granulomètrie, de la teneur en carbonate et Corg couplées à des analyses semi-quantitatives d’éléments majeurs et traces à très haute résolution temporelle par XRF Core Scanner, nous avons restitué l’histoire des apports sédimentaires du Nil, des changements de précipitation en l’Afrique du Nord, et des variations des paleo-crues du Nil au cours des 1,75 derniers millions d'années. Le premier enregistrement de Delta(18)O du foraminifère planctonique G. ruber (carotte MD90-964) de l’ensemble du Quaternaire a été obtenu à très haute résolution temporelle pour la Méditerranée orientale. Le site ODP 964 a permis de restituer la dynamique des apports de poussière saharienne à la mer ionienne durant les 1,5 derniers millions d'années. Les résultats indiquent que les changements dans les apports de sédiments transportés par le Nil et par les vents depuis les domaines sahariens sont fortement influencés par les variations de la mousson africaine. Les alternances glaciaires/interglaciaires et les variations climatiques de la transition climatique mi-Pléistocène (MPT), dans une moindre mesure, influencent également / This thesis is devoted to reconstruct the Quaternary history of African monsoon and its influences on suspended loads of the Nile River and dust production in Sahara. The materials used in this study come from two sites (MD90-964 in the eastern Levantine Basin and ODP Site 964 in the Ionian Sea) in the eastern Mediterranean Sea. Based on clay mineralogy, grain sizes, carbonate and Corg contents, and XRF core scanning analyses of Core MD90-964, we have reconstructed history of the Nile suspended discharges, precipitation in North Africa, and Nile paleoflood events during the last 1.75 Ma. On the basis of the planktonic foraminiferal Delta(18)O record of Core MD90-964, we have established for the first time in the eastern Mediterranean Sea a high-resolution planktonic foraminiferal (G. ruber) Delta(18)O record that penetrates the Quaternary period. The ODP Site 964 allows us to establish the variations of Saharan dust inputs to the eastern Mediterranean Sea during the last 1.5 Ma. Our results indicate that both fluvial sediments from the Nile and Saharan eolian dust inputs to the eastern Mediterranean Sea are greatly influenced by the variability of African monsoon. The glacial/interglacial cycles and other orbital-scale climatic events, such as the “Mid-Pleistocene Transition”, can also affect climate changes in North Africa to a minor extent.