Ce travail de thèse concerne la caractérisation physico-chimique et structurale de fibres minérales et la compréhension de mécanismes chimiques et moléculaires qui peuvent amorcer des pathologies spécifiques relatives à leur inhalation. En particulier, dans ce travail on s'est concentrés sur la fluoro-édénite, une amphibole naturelle d'origine volcanique découverte récemment à Biancavilla (Sicile), en comparaison avec d'autres fibres minérales, comme les trémolites et le chrysotile. La première partie de cette thèse concerne l'étude minéralogique, chimique et morphologique des fibres naturelles de fluoro-édénite préalablement purifiées. Ces informations ont été fondamentales pour la deuxième partie de cette étude, qui a concerné l'étude des propriétés toxicochimiques et la réactivité de surface de ce minéral. Cette approche a été enfin validée à travers des tests in vitro et in vivo de la toxicité de ces matériaux, en collaboration avec une équipe de médecins et biologistes.

Thesis--University of Oklahoma. / Includes bibliographical references (leaves 49-50).

Introduction: Asbestos has been employed in a myriad of industrial applications for more than a century. Of the 181 Mt of asbestos produced worldwide, over 31 Mt was consumed in the U.S. The production and consumption of this mineral eventually was found to cause asbestosis, lung cancer and mesothelioma. While the brunt of the human exposure to asbestos occurred in insulation work, many more workers in other jobs were expose to asbestos fibers. Very little is known about the potential exposure to asbestos in research labs. Goal: In order to investigate potential research lab work exposures, we simulated lab work with various asbestos-containing items commonly found in research laboratories: 6 wire gauze pads, 3 gloves, 3 beaker tongs, and 3 Transite boards. All samples were analyzed by Phase Contrast Microscopy and, when appropriate, by Transmission Electron Microscopy and Polarized Light Microscopy. Results: All tested items were confirmed by bulk sampling to have asbestos fibers in their composition. Exposures from the 7 wire gauze pads were significantly lower than the PEL and the excursion limit, the highest exposure concentration measuring 0.029 f/cc. For the 3 beaker tongs with asbestos sleeves, exposure was below the PEL for 2 of the 3, with one resulting in an exposure of 0.160 f/cc (8-h TWA = 0.01 f/cc). For the Transite boards had the highest exposures of all tested items, with a maximum concentration of 0.320 f/cc (8-h TWA = 0.02 f/cc). Conclusion: Asbestos exposure in our simulated research lab work was significantly lower than any of the historical exposures associated with asbestos-related disease including cancer.

No description available.

Dissertation (Ph.D.)--University of South Florida, 2006. / Title from PDF of title page. Document formatted into pages; contains 153 pages. Includes vita. Includes bibliographical references.

In our republic, occupational exposure to asbestos has been restricted to jobs concerned with disposal of products, materials and buildings containing asbestos, and research work studying asbestos fibres. The reason consists in health risks as all kinds of asbestos belong to high-risk carcinogens. The asbestos fibre related diseases should be reported. All data connected are kept in the National Institute of Public Health (NIPH) in Prague. The purpose of this study was to find out how much people are aware of the risks related to asbestos and find people who suffered from asbestos dust-induced disease, i.e. mesothelioma of pleura. The quantitative method was used to summarise information on asbestos-induced disease occurence in 1970-2010 available in the National Institute of Public Health in Prague. Along with that, the work maps the population awareness of asbestos risks. The thesis itself can be divided into two parts. The first one contains information based on data collection while the other part deals with data of NIPH in Prague. Two hypotheses were predicted: Hypothesis H1: People are aware of the material containing asbestos. Hypothesis H2: People are aware of negative impact of asbestos on human health. Both hypotheses were proved. Three hypotheses were suggested in the other part: Hypothesis H3: Latency, the time between first exposure to manifestation of disease, is never less than 20 years. Hypothesis H4: Incidence of mesothelioma of pleura and peritoneum is higher in people aged 60-69. Hypothesis H5: Smoking affects the course of the disease negatively. Hypotheses H3 and H4 were proved. Hypothesis H5 cannot be neither proved or disproved. Although the number of smokers among mesothelioma patients was higher, there is no evidence of negative effect of smoking on the disease. To prove this hypothesis, the data colllection should be larger. Findings of the study proved the time of exposure to asbestos fibres does not affect the occurence of this disease. The findings can be used in further research studies.

The commercial mining of asbestos occurred in four Provinces of South Africa (Northern Cape, North West, Limpopo and Mpumalanga). It was initiated in the late 1800's and lasted for over a hundred years into the beginning of this century. As a producer of amphibole asbestos, South Africa far outpaced every other country being responsible for 97% of global production. The last crocidolite mine closed in 1996 and chrysotile in 2002. Anecdotal information concerning environmental contamination as a result of the former mining activities and the improper disposal of mine waste tailings has been reported by a variety of authors. Few comprehensive or systematic surveys have been conducted to date to document this issue and very little quantifiable research has been completed on the communities located in close proximity to the former mine sites to determine the extent of contamination. In 2004-2006 communities were surveyed within the Northern Cape and North West Provinces to determine the extent and severity of environmental contamination. This research developed and applied a methodology to select those communities suspected of environmental contamination, a targeted survey methodology, and a protocol for rapid sample laboratory analysis. A total of 41 communities were initially predicted by the model to be suspected for environmental asbestos contamination. Based on the inclusion of local knowledge, a final 36 communities were selected for a screening-level field assessment, 34 of which were found to contain environmental asbestos contamination at rates ranging from 20 to 100% of the surveyed locations. A total of 1 843 samples of soil and building material were collected in the screening level assessment. One community (Ga-Mopedi) was selected as being representative of the total cohort and a more detailed house to house survey was completed. A total of 1 486 samples were collected during the detailed survey. Results of the detailed survey revealed 26.2% of the homes were contaminated with asbestos containing soil and/or building material. A theoretical quantitative cumulative exposure assessment was developed to estimate the disease burden within the study area population of 126,130 individuals within the surveyed communities resulting in a predicted range of 25-52.4 excess deaths per year from lung cancer and mesothelioma due solely to environmental exposures to asbestos pollution.

Le mésothéliome est une tumeur maligne rare des séreuses, au pronostic sombre, dont le facteur de risque principal connu est l’exposition à l’amiante. Il se déclare avec un temps de latence d’environ 30 ans après le début de l’exposition, atteint principalement la plèvre et touche majoritairement les hommes. L’analyse de cette pathologie, reconnue comme une maladie professionnelle et pour laquelle une Déclaration Obligatoire de maladie a été instituée en janvier 2012, s’est focalisée jusqu’alors essentiellement sur l’homme, tant sur le plan épidémiologique que sur le plan biologique. Il apparaît pourtant dans la littérature internationale des différences notables par sexe.Ces constations posent la question d’investiguer d’autres facteurs de risque, en particulier l’hypothèse d’une prédisposition génétique, les mécanismes biologiques intervenant dans les voies de la carcinogenèse du mésothéliome étant partiellement connus. Ceci incite à étudier les facteurs épidémiologiques, cliniques, biologiques et immunohistochimiques, prédisposant chez la femme au développement du mésothéliome pleural et péritonéal, et d’évaluer leurs impacts pronostiques, à partir des cas diagnostiqués entre 1998 et 2013, issus de la plus importante base de données française. Elle incite également à établir un état des lieux épidémiologique actualisé par sexe en France pour le mésothéliome pleural et péritonéal ; ces données étant inexistantes pour la France pour le péritoine. / Mesothelioma is a rare malignant serous tumor with a poor prognosis of which asbestos exposure is the major known risk factor. It occurs with a latent period about 30 years after exposure, reaches mainly the pleura and affects mainly the men. The study of this pathology, recognized as an occupationnal disease and for which a Mandatory Declaration of Disease was introduced in January 2012, focused until then mainly on men, both epidemiologically and biologically. However, there are significant gender differences in the international literature.These results raise the question of investigating other risk factors, in particular the hypothesis of genetic predisposition, the biological mechanisms involved in mesothelioma carcinogenesis pathways being partially known. This encourages the study of epidemiological, clinical, biological and immunohistochemical factors predisposing women to the development of pleural and peritoneal mesothelioma, and to evaluate their prognostic impacts, based on cases diagnosed between 1980 and 2015, from the largest French database. It also encourages the establishment of an updated epidemiological inventory by gender in France for pleural and peritoneal mesothelioma; these data are non-existent for peritoneum.

This diploma thesis deals with fiber-cement composites. Input materials are investigated for the production of fiber cement, are examined, the production and parameters of the pulp were monitored. Further, Hatschek's production technology and requirements for corrugated fiber-cement roofing are described. In the practical part the individual input materials and parameters of ground pulp were verified. The problem with production of samples and difference in the fineness of pulp milling in fiber cement products has been solved.

Occupational exposure to asbestos has been associated with increased incidence of pulmonary interstitial fibrosis, mesothelioma of the pleura, and bronchogenic carcinoma. Although the mechanism by which asbestos causes cancer remains unknown , iron associated with asbestos is thought to play a role in the pathogenic effects of fibers. The aim of this research was to examine and compare the asbestos-induced signaling phenomena in relevant human lung and pleural target cells, and to deter mine the role of iron from asbestos fibers in these events. Exposure of human airway epithelial (A549) cells, human pleural mesothelial (METSA) cells, and normal human small airway epithelial (SAEC) cells to asbestos resulted in a significant dephosphorylation and inactivation of epidermal growth factor receptor (EGFR). The effects of three types of asbestos, i.e. crocidolite, amosite and chrysotile, on the EGFR phosphorylation state in A549 cells appeared to be directly related to the amount of iron mobilized from these fibers. These results strongly suggest that iron plays an important role in asbestos induced inactivation of EGFR. We observed that exposure of A549 and SAEC cells to crocidolite , but not inert titanium dioxide , led to a significant time- and dose-dependent inactivation of the main EGFR signaling pathways, including Akt and extracellular signal-regulated kinase 1/2 (ERKI/2) pathways. Crocidolite also initiated apoptosis via pathways involving activation of p38 mitogen-activated protein kinase (MAPK), caspase -3 and -9, and cleavage of poly(ADP-ribose) polymerase (PARP). Prevention of these effects with an iron chelator or endocytosis inhibitors strongly suggests that iron mobilized from fibers inside the cells initiates the observed events. Inhibition of p38 MAPK with SB203580 prevented inactivation of EGFR , inactivation of EGFR-associated survival pathways, and initiation of apoptosis. Our results also suggest that p38 MAPK-dependent protein serine/threonine phosphatase activation plays an important role in the observed phenomena. Taken together , it appears that iron-dependent p38 MAPK activation, through a serine/threonine phosphatase-mediated mechanism , regulates asbestos-induced apoptosis in human lung epithelial cells. We speculate that apoptosis of human lung target cells induced by asbestos fibers is a pathologic feature in lung injury and may account for some of the pulmonary toxicity of the fibers.