The aims of the studies underlying this thesis were to assess the exposure to quartz in Swedish iron foundries and to determine the cancer morbidity for Swedish foundry workers. A cohort of 3,045 foundry workers and a final measurement database of 2,333 number of samples was established. The exposure measurements showed high levels of respirable quartz, in particular for fettlers and furnace and ladle repair workers with individual 8 hr TWA (GM=0.041 and 0.052 mg/m3; range 0.004-2.1 and 0.0098-0.83 mg/m3). In our database, the quartz concentrations as 8hr TWAs of current and historical data varied between 0.0018 and 4.9 mg/m3, averaging 0.083 mg/m3, with the highest exposures for fettlers (0.087 mg/m3) and furnace and ladle repair workers (0.42 mg/m3). The exposure for workers using respirators assuming full effect when used were assessed quantitatively, revealing workers with actual exposure exceeding the occupational exposure limits. Overall cancer morbidity was not increased, but the incidence of lung cancer was significantly elevated (SIR 1.61; 95 % CI 1.20-2.12). In the cohort study, significant associations between lung cancer and cumulative quartz exposure were detected for quartz doses of 1-2 mg/m3 * year (SIR 2.88; 95 % CI 1.44-5.16) and >2 mg/m3 * year (SIR 1.68; 95 % CI 1.07- 2.52). These findings were not confirmed in the case-control analysis. The agreement between the estimated exposure in our early historical model and the development model showed a regression coefficient of 2.42, implying an underestimation of the historical exposure when using the development model data. The corresponding comparison between the development and the validation model based on our survey data showed a B of 0.31, implying an overestimation of present exposures when using data from the validation model. The main conclusions of the thesis are that certain foundry workers are still exposed to high levels of quartz, and the overall excess lung cancer could not be confirmed in the exposure-response analysis.

Each hydraulic fracturing well uses up to 5,000 tons of silica-containing sand, or proppant, during its operational lifetime. Over one million wells are currently in operation across the continental United States. The resulting increase in demand resulted in the production of 54 million metric tons of sand for use as hydraulic fracturing proppant in 2015. The goal of this study was to determine the relative risk of occupational exposure to respirable crystalline silica to workers performing tasks associated with mining, processing, and transport of proppant. Sand samples were aerosolized in an enclosed chamber. Bulk and respirable samples were submitted to a commercial lab for silica analysis. A risk ratio was calculated by comparing respirable dust concentrations to the current occupational safety regulations. Raw sand produced higher concentrations of respirable dust and a higher risk ratio (3.2), while processed dust contained higher percentages of respirable crystalline silica but a lower risk ratio (0.5). When vibration was introduced prior to aerosolization, concentrations tended to increase as vibration times increased, resulting in an increase of the associated risk ratio (2.3). Results of the study indicate that workers in sand mines and workers exposed to proppant that has undergone low-frequency vibration are at increased risk of exposure to respirable crystalline silica compared to workers who are exposed to proppant that has not undergone vibration.

Silica sand is used in the hydraulic fracturing process as a proppant—a material that holds open fissures in a rock formation to allow oil and gas to escape. Due to the increased demand for proppant sand, numerous sand mining and processing facilities have been constructed in the vicinity of small communities. Silica sand contains crystalline silica, which can cause chronic health problems such as silicosis. This study monitored airborne particulate matter at residences within 800 m from the facilities property line, with active mining, processing, and/or transport. Real-time particulate air monitoring with automated acquisition of explanatory variables: sound and motion to detect transportation; and wind speed and direction to attribute measured PM concentrations to specific sources. The highest daily mean concentrations were 37.3 μg/m3 for PM10 and 14.5 μg/m3 for PM2.5, both of which are well below the EPA National Ambient Air Quality Standards. Using conditional probability plots of PM relative to wind direction elevated short-term (20 second) peak concentrations were more likely to occur when the wind was blowing from the sand facility. These peak concentrations occurred infrequently, ranging from 0% to 3% of the sampling time. This study did not measure crystalline silica specifically, but low PM concentrations were observed so crystalline silica is expected to be low. Since PM concentrations were low near the facilities, it can be concluded that these facilities do not increase airborne particulate matter to hazardous concentrations that could cause chronic health conditions.

Orientador: Gladis Camarini / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-10T20:33:15Z (GMT). No. of bitstreams: 1 Moreira-Lima_MariaMargaridaTeixeira_M.pdf: 1594548 bytes, checksum: 38f498b14a56cd02f47e608c6fa62728 (MD5) Previous issue date: 2007 / Resumo: A poeira gerada no processo de fabricação de materiais cerâmicos pode ser um agente de risco à saúde dos trabalhadores, em especial quando em sua composição houver a presença de polimorfos da sílica nas formas cristalinas do a-quartzo e da cristobalita. A exposição ocupacional à poeira respirável desses polimorfos pode ocasionar o aparecimento da silicose e de outras doenças associadas. Na indústria de revestimentos cerâmicos as informações sobre as características da poeira gerada nos seus processos e sobre a prevalência da silicose no setor são insuficientes para definir a magnitude do risco da exposição ocupacional à sílica. Este estudo de campo busca identificar parâmetros físicos e a concentração em sílica cristalina do material particulado suspenso no ar em indústrias de revestimentos cerâmicos para pisos e paredes. Foram selecionadas nove indústrias no município de Santa Gertrudes, no estado de São Paulo, com processo de fabricação por via seca, onde a matéria-prima principal é a argila vermelha proveniente da Formação Corumbataí. O estudo realizou-se por meio da observação sistemática das etapas do processo industrial, da coleta e análise de amostras da poeira presente nos ambientes de trabalho e da análise mineralógica da massa cerâmica manufaturada. As amostras de poeira foram analisadas por ravimetria e por difratometria de raios-X (DRX). Foi determinada a presença na poeira de partículas com tamanho na fração respirável (< 10 µm), sendo identificado o a-quartzo em 72% das amostras de poeira respirável analisadas. Não se encontraram outros polimorfos da sílica cristalina na poeira coletada. As avaliações realizadas indicaram concentrações de a-quartzo respirável entre 0,01 mg/m³ e 0,16 mg/m³, sendo a concentração média de a-quartzo respirável nos setores de moagem e de recepção de massa de 0,06 mg/m³, nos setores de prensas de 0,03 mg/m³, nas linhas de esmaltação de 0,02 mg/m³ e na preparação dos esmaltes e engobe de 0,09 mg/m³. Foi caracterizada por DRX a presença de minerais do grupo das micas, dos feldspatos e da esmectita na composição das massas cerâmicas analisadas, juntamente com a hematita e o quartzo, como mineral predominante / Abstract: Dust generated in the process of manufacturing ceramic materials may be a hazardous agent to the health of workers, especially when silica polymorphs in crystal forms of a-quartz and cristobalite are present in its composition. Occupational exposure to respirable dust of such polymorphs may lead to the onset of lung disease named silicosis and other associated diseases. In the ceramic wall and floor tiles industry data on the characteristics of dust generated in their processes and on the prevalence of silicosis in the sector are not sufficient to define the magnitude of occupational exposure risk to silica in this industry. This field study aims to identify physical parameters and the mass concentration and the composition in crystalline silica of airborne particulate material in industries of glazed ceramic tiles for floors and walls. Nine plants in Santa Gertrudes Municipality, São Paulo State, with dry manufacturing process, where the main raw material is red clay from the Corumbataí Formation have been selected. The study was conducted through systematic observation of the industrial process steps with dust generation, the collection and analysis of air samples from the environments and the mineralogical analysis of the raw ceramic bodies manufactured. Dust samples were analyzed with gravimetric and X-ray diffractometry (XRD) techniques. The air samples indicated that there was dust in the respirable fraction (< 10 µm) and the a-quartz was identified in 72% of the analyzed respirable dust samples. Other polymorphs of the crystalline silica were not found in the collected dust. The dust samples indicated concentrations of respirable a-quartz between 0.01 mg/m³ and 0.16 mg/m³ in the main stages of the process. The mean concentration of respirable a-quartz in the sectors of clay grinding was 0.06 mg/m³, in the pressing sectors it was 0.03 mg/m³, in the glazing lines it was 0.02 mg/m³ and in the preparation of enamels and engobe sectors it was 0.09 mg/m³. Minerals of the group of the micas, feldspars and smectite had been identified by XRD in the composition of all the ceramic masses, together with hematite and quartz, as the predominant mineral / Mestrado / Arquitetura e Construção / Mestre em Engenharia Civil

L’exposition prolongée par inhalation à des poussières de taille respirable contenant de la silice cristalline est reconnue pour causer des maladies respiratoires dont le cancer du poumon et la silicose. De nombreuses études ont relevé la surexposition des travailleurs de la construction à la silice cristalline, puisque ce composé est présent dans de nombreux matériaux utilisés sur les chantiers. L’évaluation de l’exposition à la silice cristalline dans cette industrie constitue un défi en raison de la multitude de conditions de travail et de la nature éphémère des chantiers. Afin de mieux cerner cette problématique, une banque de données d’exposition professionnelle compilée à partir de la littérature a été réalisée par une équipe de l’Université de Montréal et de l’IRSST, et constitue le point de départ de ce travail. Les données présentes dans la banque ont été divisées en fonction de la stratégie d’échantillonnage, résultant en deux analyses complémentaires ayant pour objectif d’estimer les niveaux d’exposition sur le quart de travail en fonction du titre d’emploi, et selon la nature de la tâche exécutée. La méthode de Monte Carlo a été utilisée pour recréer les échantillons provenant de données rapportées sous forme de paramètres de synthèse. Des modèles Tobit comprenant les variables de titre d’emploi, tâche exécutée, durée, année et stratégie d’échantillonnage, type de projet, secteur d’activité, environnement et moyens de maîtrise ont été développés et interprétés par inférence multimodèle. L’analyse basée sur le quart de travail a été réalisée à partir de 1346 données d’exposition couvrant 11 catégories de titre d’emploi. Le modèle contenant toutes les variables a expliqué 22% de la variabilité des mesures et la durée, l’année et la stratégie d’échantillonnage étaient d’importants prédicteurs de l’exposition. Les chantiers de génie civil et les projets de nouvelle construction étaient associés à des expositions plus faibles, alors que l’utilisation de moyens de maîtrise diminuait les concentrations de 18% à l’extérieur et de 24% à l’intérieur. Les moyennes géométriques les plus élevées prédites pour l’année 1999 sur 8 heures étaient retrouvées chez les foreurs (0.214 mg/m3), les travailleurs souterrains (0.191 mg/m3), les couvreurs (0.146 mg/m3) et les cimentiers-applicateurs (0.125 mg/m3). 1566 mesures réparties en 27 catégories de tâches étaient contenues dans la seconde analyse. Le modèle contenant toutes les variables a expliqué 59% des niveaux d’exposition, et l’ensemble des variables contextuelles étaient fortement prédictives. Les moyennes géométriques prédites pour l’année 1998 et selon la durée médiane par tâche dans la banque de données étaient plus élevées lors du bouchardage du béton (1.446 mg/m3), du cassage de pièces de maçonnerie avec autres outils (0.354 mg/m3), du décapage au jet de sable (0.349 mg/m3) et du meulage de joints de brique (0.200 mg/m3). Une diminution importante des concentrations a été observée avec les systèmes d’arrosage (-80%) et d’aspiration des poussières (-64%) intégrés aux outils. L’analyse en fonction des titres d’emploi a montré une surexposition généralisée à la valeur guide de l’ACGIH et à la norme québécoise, indiquant un risque à long terme de maladies professionnelles chez ces travailleurs. Les résultats obtenus pour l’évaluation en fonction de la tâche exécutée montrent que cette stratégie permet une meilleure caractérisation des facteurs associés à l’exposition et ainsi de mieux cibler les priorités d’intervention pour contrôler les niveaux d’exposition à la silice cristalline sur les chantiers de construction durant un quart de travail. / Chronic inhalation of respirable inorganic dusts containing crystalline silica is linked to occupational respiratory diseases such as lung cancer and silicosis. Several studies have documented the overexposure to respirable crystalline silica in construction workers, as this compound is found in several building materials and many operations can release fine suspended particles. Comprehensive quantitative exposure assessment in this industry is challenging due to the variety in tasks performed, materials used and environmental conditions between work sites, the mobile workforce and the temporary nature of construction sites. An occupational exposure database of silica exposure was compiled from the literature by a research group from the Université de Montréal and the Institut de recherche en santé et en sécurité du travail (IRSST) to address this issue. The exposure data contained in the database were separated on the basis of sampling strategies, which resulted in two separate – but complementary – analyses. The first analysis was restricted to samples collected to compare levels with an occupational exposure limit, in order to estimate work-shift respirable crystalline silica exposure by construction trade. The second analysis used measurements collected under a task-based sampling strategy in order to estimate the exposure levels associated with specific activities. Monte-Carlo simulation was used to recreate individual exposures from measurements reported as summary statistics. Modeling was performed using Tobit models within a multimodel inference framework, with construction trade, task, sampling duration, year and strategy, project type, construction sector, workspace and control methods as potential predictors. The dataset for the analysis by construction trade was comprised of 1346 exposure measurements and included 11 trade categories. The model containing all the variables explained 22% of the exposure variability and the sampling duration, year and strategy were identified as important predictors. Civil engineering and roadwork sites as well as new construction projects were associated with lower exposure levels, while the use of control methods reduced silica concentrations by 18% outdoors and 24% indoors. Predicted geometric means (GM) for year 1999 were the highest for drillers (0.214 mg/m3), underground workers (0.191 mg/m3), roofers (0.146 mg/m3) and cement grinders/finishers (0.125 mg/m3), based on a 8-hour shift. Heavy equipment operators (0.041 mg/m3) and foremen (0.047 mg/m3) had the lowest predicted GMs. 1566 task-based measurements, representing 27 task categories, were included in the activity-specific dataset. The proportion of variance explained by the model containing all the variables was 59%, and all the variables investigated had a strong influence on the exposure levels. Predictions were made based on the year 1998 and the median duration by task in the dataset. The largest predicted GMs were associated with the following operations: scabbling concrete (1.446 mg/m3), chipping with other tools (0.354 mg/m3), abrasive blasting (0.349 mg/m3) and tuck point grinding (0.200 mg/m3). Important reductions in exposure levels were found with the use of tool-integrated water sprays (-80%) and local exhaust ventilation (-64%). Important overexposure to the ACGIH Threshold Limit Value and the Québec exposure limit was found for all the trades investigated, indicating a long-term risk of silica-related occupational diseases. The results of the task-based analysis suggest that this sampling strategy provides a better characterization of the factors affecting exposure and the impacts of engineering dust control methods to control long-term exposure levels.

Objetivo. No Brasil encontram-se em crescimento os índices de prevalência das doenças crônicas causadas pela exposição dos trabalhadores a poeiras minerais. Realizou-se estudo com objetivo de avaliar as condições de trabalho e de saúde dos trabalhadores em marmorarias e propor ações preventivas. Métodos. Realizou-se estudo transversal em 27 marmorarias, no Município de São Paulo que executavam o beneficiamento final de rochas ornamentais, incluindo: a) avaliação da exposição a poeiras e à sílica cristalina respirável por meio de coleta de amostras de ar (n=762), análise por gravimetria e Difração de Raios X e acumulação das exposições estimadas por função conforme história ocupacional; b) aplicação de questionário de sintomas respiratórios (n=267) e avaliação médica, por espirometria e radiogradia de tórax; d) correlação dos resultados de exposição acumulada com achados clínicos e radiológicos por meio de análises estatísticas; e) levantamento de informações sobre os processos de trabalho e alternativas de controle. Resultados. Para os acabadores encontrou-se a maior exposição: concentração de 0,36 mg/m³ (IC95% 0,29 e 0,42) para os granitos e de 0,19 mg/m3 (IC95% 0,16-0,22) para a mistura de matérias-primas. Para estimativa de exposição acumulada à sílica cristalina respirável com mediana de 0,56 mg/m3-anos existiu risco de Odds Ratio igual a 1,2 (IC95% 1,02-1,40) de o trabalhador exposto apresentar classificação radiológica com alterações, presença de pequenas opacidades - profusão ³ 0/1, em relação a um trabalhador não-exposto. A população possuía baixo nível de escolaridade e de renda familiar, com média de idade 35,8 (±11,6) anos. Conclusões. Há exposição excessiva à sílica cristalina respirável nas marmorarias, com valores de concentração ultrapassando até 54 vezes o valor de referência recomendado pela NIOSH 0,05 mg/m3. As matérias-primas mais perigosas foram rochas silicáticas (silestoneÒ, granitos, arenitos e quartzitos). Entre as medidas de controle para as poeiras, caracterizaram-se como mais eficientes as aplicadas a úmido em máquinas e ferramentas. / Objective. In Brazil it can be seen growing prevalence rates of chronic diseases due to occupational exposure to mineral dusts, being silicosis the greater prevalence of pneumoconiosis. A study was carried out with the aim to evaluate the work conditions and of the workers’ health in granite and marble sheds and to propose preventive actions. Methods: A cross sectional study was performed among 27 sheds in Sao Paulo county that perform the finishing work of ornamental rocks. The study included: a) evaluation of dust exposure and respirable crystalline silica, by means of air sampling (n=762), analysis by gravimetry and X-Ray diffraction, and cumulative silica exposure estimates in each job according to the occupational history; b) applying a questionnaire of respiratory symptoms (n=267) and medical evaluation, espirometry and chest X-Ray; d) results correlation of cumulative exposure with the clinical and radiological data by statistical means; e) search of working process information and control alternatives. Results: Finishing workers had the greater exposition: concentration of 0.36 mg/m3 (CI95% 0.29-0.42) for granites and of 0.19 mg/m3 (CI95% 0.16-0.22) for the mixture of raw materials. To the estimated cumulative exposure to respirable crystalline silica with median equal to 0.56 mg/m3-years there was a risk Odds Ratio =OR=1.20 (CI95%1.02 1.40) of the exposed worked to present an altered radiological classification with alterations, presence of small opacities - perfusion &#8805;0/1, in relation to a non exposed worker. The population studied had low scholar education and low familiar income, with average age 35.8 (±11,6) years. Conclusions: There is excessive exposure to respirable crystalline silica in sheds with concentrations 54 times over the recommended exposure limit by NIOSH of 0.05 mg/m3. The most dangerous raw materials were silicatious rocks (silestoneÒ, granites, sandstones and quartzites). Among the control measures for dusts, were characterized as more efficient the applied ones the humid in machines and tools.

Objetivo. No Brasil encontram-se em crescimento os índices de prevalência das doenças crônicas causadas pela exposição dos trabalhadores a poeiras minerais. Realizou-se estudo com objetivo de avaliar as condições de trabalho e de saúde dos trabalhadores em marmorarias e propor ações preventivas. Métodos. Realizou-se estudo transversal em 27 marmorarias, no Município de São Paulo que executavam o beneficiamento final de rochas ornamentais, incluindo: a) avaliação da exposição a poeiras e à sílica cristalina respirável por meio de coleta de amostras de ar (n=762), análise por gravimetria e Difração de Raios X e acumulação das exposições estimadas por função conforme história ocupacional; b) aplicação de questionário de sintomas respiratórios (n=267) e avaliação médica, por espirometria e radiogradia de tórax; d) correlação dos resultados de exposição acumulada com achados clínicos e radiológicos por meio de análises estatísticas; e) levantamento de informações sobre os processos de trabalho e alternativas de controle. Resultados. Para os acabadores encontrou-se a maior exposição: concentração de 0,36 mg/m³ (IC95% 0,29 e 0,42) para os granitos e de 0,19 mg/m3 (IC95% 0,16-0,22) para a mistura de matérias-primas. Para estimativa de exposição acumulada à sílica cristalina respirável com mediana de 0,56 mg/m3-anos existiu risco de Odds Ratio igual a 1,2 (IC95% 1,02-1,40) de o trabalhador exposto apresentar classificação radiológica com alterações, presença de pequenas opacidades - profusão ³ 0/1, em relação a um trabalhador não-exposto. A população possuía baixo nível de escolaridade e de renda familiar, com média de idade 35,8 (±11,6) anos. Conclusões. Há exposição excessiva à sílica cristalina respirável nas marmorarias, com valores de concentração ultrapassando até 54 vezes o valor de referência recomendado pela NIOSH 0,05 mg/m3. As matérias-primas mais perigosas foram rochas silicáticas (silestoneÒ, granitos, arenitos e quartzitos). Entre as medidas de controle para as poeiras, caracterizaram-se como mais eficientes as aplicadas a úmido em máquinas e ferramentas. / Objective. In Brazil it can be seen growing prevalence rates of chronic diseases due to occupational exposure to mineral dusts, being silicosis the greater prevalence of pneumoconiosis. A study was carried out with the aim to evaluate the work conditions and of the workers’ health in granite and marble sheds and to propose preventive actions. Methods: A cross sectional study was performed among 27 sheds in Sao Paulo county that perform the finishing work of ornamental rocks. The study included: a) evaluation of dust exposure and respirable crystalline silica, by means of air sampling (n=762), analysis by gravimetry and X-Ray diffraction, and cumulative silica exposure estimates in each job according to the occupational history; b) applying a questionnaire of respiratory symptoms (n=267) and medical evaluation, espirometry and chest X-Ray; d) results correlation of cumulative exposure with the clinical and radiological data by statistical means; e) search of working process information and control alternatives. Results: Finishing workers had the greater exposition: concentration of 0.36 mg/m3 (CI95% 0.29-0.42) for granites and of 0.19 mg/m3 (CI95% 0.16-0.22) for the mixture of raw materials. To the estimated cumulative exposure to respirable crystalline silica with median equal to 0.56 mg/m3-years there was a risk Odds Ratio =OR=1.20 (CI95%1.02 1.40) of the exposed worked to present an altered radiological classification with alterations, presence of small opacities - perfusion &#8805;0/1, in relation to a non exposed worker. The population studied had low scholar education and low familiar income, with average age 35.8 (±11,6) years. Conclusions: There is excessive exposure to respirable crystalline silica in sheds with concentrations 54 times over the recommended exposure limit by NIOSH of 0.05 mg/m3. The most dangerous raw materials were silicatious rocks (silestoneÒ, granites, sandstones and quartzites). Among the control measures for dusts, were characterized as more efficient the applied ones the humid in machines and tools.

L’exposition prolongée par inhalation à des poussières de taille respirable contenant de la silice cristalline est reconnue pour causer des maladies respiratoires dont le cancer du poumon et la silicose. De nombreuses études ont relevé la surexposition des travailleurs de la construction à la silice cristalline, puisque ce composé est présent dans de nombreux matériaux utilisés sur les chantiers. L’évaluation de l’exposition à la silice cristalline dans cette industrie constitue un défi en raison de la multitude de conditions de travail et de la nature éphémère des chantiers. Afin de mieux cerner cette problématique, une banque de données d’exposition professionnelle compilée à partir de la littérature a été réalisée par une équipe de l’Université de Montréal et de l’IRSST, et constitue le point de départ de ce travail. Les données présentes dans la banque ont été divisées en fonction de la stratégie d’échantillonnage, résultant en deux analyses complémentaires ayant pour objectif d’estimer les niveaux d’exposition sur le quart de travail en fonction du titre d’emploi, et selon la nature de la tâche exécutée. La méthode de Monte Carlo a été utilisée pour recréer les échantillons provenant de données rapportées sous forme de paramètres de synthèse. Des modèles Tobit comprenant les variables de titre d’emploi, tâche exécutée, durée, année et stratégie d’échantillonnage, type de projet, secteur d’activité, environnement et moyens de maîtrise ont été développés et interprétés par inférence multimodèle. L’analyse basée sur le quart de travail a été réalisée à partir de 1346 données d’exposition couvrant 11 catégories de titre d’emploi. Le modèle contenant toutes les variables a expliqué 22% de la variabilité des mesures et la durée, l’année et la stratégie d’échantillonnage étaient d’importants prédicteurs de l’exposition. Les chantiers de génie civil et les projets de nouvelle construction étaient associés à des expositions plus faibles, alors que l’utilisation de moyens de maîtrise diminuait les concentrations de 18% à l’extérieur et de 24% à l’intérieur. Les moyennes géométriques les plus élevées prédites pour l’année 1999 sur 8 heures étaient retrouvées chez les foreurs (0.214 mg/m3), les travailleurs souterrains (0.191 mg/m3), les couvreurs (0.146 mg/m3) et les cimentiers-applicateurs (0.125 mg/m3). 1566 mesures réparties en 27 catégories de tâches étaient contenues dans la seconde analyse. Le modèle contenant toutes les variables a expliqué 59% des niveaux d’exposition, et l’ensemble des variables contextuelles étaient fortement prédictives. Les moyennes géométriques prédites pour l’année 1998 et selon la durée médiane par tâche dans la banque de données étaient plus élevées lors du bouchardage du béton (1.446 mg/m3), du cassage de pièces de maçonnerie avec autres outils (0.354 mg/m3), du décapage au jet de sable (0.349 mg/m3) et du meulage de joints de brique (0.200 mg/m3). Une diminution importante des concentrations a été observée avec les systèmes d’arrosage (-80%) et d’aspiration des poussières (-64%) intégrés aux outils. L’analyse en fonction des titres d’emploi a montré une surexposition généralisée à la valeur guide de l’ACGIH et à la norme québécoise, indiquant un risque à long terme de maladies professionnelles chez ces travailleurs. Les résultats obtenus pour l’évaluation en fonction de la tâche exécutée montrent que cette stratégie permet une meilleure caractérisation des facteurs associés à l’exposition et ainsi de mieux cibler les priorités d’intervention pour contrôler les niveaux d’exposition à la silice cristalline sur les chantiers de construction durant un quart de travail. / Chronic inhalation of respirable inorganic dusts containing crystalline silica is linked to occupational respiratory diseases such as lung cancer and silicosis. Several studies have documented the overexposure to respirable crystalline silica in construction workers, as this compound is found in several building materials and many operations can release fine suspended particles. Comprehensive quantitative exposure assessment in this industry is challenging due to the variety in tasks performed, materials used and environmental conditions between work sites, the mobile workforce and the temporary nature of construction sites. An occupational exposure database of silica exposure was compiled from the literature by a research group from the Université de Montréal and the Institut de recherche en santé et en sécurité du travail (IRSST) to address this issue. The exposure data contained in the database were separated on the basis of sampling strategies, which resulted in two separate – but complementary – analyses. The first analysis was restricted to samples collected to compare levels with an occupational exposure limit, in order to estimate work-shift respirable crystalline silica exposure by construction trade. The second analysis used measurements collected under a task-based sampling strategy in order to estimate the exposure levels associated with specific activities. Monte-Carlo simulation was used to recreate individual exposures from measurements reported as summary statistics. Modeling was performed using Tobit models within a multimodel inference framework, with construction trade, task, sampling duration, year and strategy, project type, construction sector, workspace and control methods as potential predictors. The dataset for the analysis by construction trade was comprised of 1346 exposure measurements and included 11 trade categories. The model containing all the variables explained 22% of the exposure variability and the sampling duration, year and strategy were identified as important predictors. Civil engineering and roadwork sites as well as new construction projects were associated with lower exposure levels, while the use of control methods reduced silica concentrations by 18% outdoors and 24% indoors. Predicted geometric means (GM) for year 1999 were the highest for drillers (0.214 mg/m3), underground workers (0.191 mg/m3), roofers (0.146 mg/m3) and cement grinders/finishers (0.125 mg/m3), based on a 8-hour shift. Heavy equipment operators (0.041 mg/m3) and foremen (0.047 mg/m3) had the lowest predicted GMs. 1566 task-based measurements, representing 27 task categories, were included in the activity-specific dataset. The proportion of variance explained by the model containing all the variables was 59%, and all the variables investigated had a strong influence on the exposure levels. Predictions were made based on the year 1998 and the median duration by task in the dataset. The largest predicted GMs were associated with the following operations: scabbling concrete (1.446 mg/m3), chipping with other tools (0.354 mg/m3), abrasive blasting (0.349 mg/m3) and tuck point grinding (0.200 mg/m3). Important reductions in exposure levels were found with the use of tool-integrated water sprays (-80%) and local exhaust ventilation (-64%). Important overexposure to the ACGIH Threshold Limit Value and the Québec exposure limit was found for all the trades investigated, indicating a long-term risk of silica-related occupational diseases. The results of the task-based analysis suggest that this sampling strategy provides a better characterization of the factors affecting exposure and the impacts of engineering dust control methods to control long-term exposure levels.

Contexte : L’objectif de cette thèse est d’étudier l’association entre l’exposition professionnelle à l'amiante et à la silice cristalline avec les phénotypes du cancer broncho-pulmonaire. Un autre objectif est d'évaluer la modification de l'effet de l'association entre le tabagisme et le type histologique, la localisation de la tumeur, et l’âge au diagnostic par l’exposition professionnelle à l'amiante ou à la silice cristalline.Méthodes : L’étude CaProMat est une étude « case-only » rétrospective qui inclut9623 cas de cancer broncho-pulmonaire Français et Canadiens. Tous les cas de cancer broncho-pulmonaire ont été identifiés d’une façon histologique. Les données ont été collectées par des fichiers médicaux et par des questionnaires standardisés.Deux Matrices Emplois-Expositions (MEEs) ont été utilisées pour évaluer rétrospectivement l'exposition professionnelle à l'amiante et à la silice cristalline.Résultats : Il n’y a pas de différence de prévalence de l'exposition professionnelle à l'amiante pour les types histologiques. Pour la silice cristalline, un excès limite de la prévalence de l'exposition a été observé pour le carcinome épidermoïde. La prévalence a été maximisée chez les cas diagnostiqués entre 50 et 59 ans pour l'amiante et moins de 50 ans pour la silice cristalline. Une exposition supplémentaire à l'amiante ou à la silice cristalline n'a pas modifié l'effet du tabagisme pour les types histologiques, la localisation de la tumeur ou l'âge au diagnostic.Conclusion : Le type histologique, la localisation de la tumeur, et l'âge au diagnostic ne peuvent pas être utilisés comme indicateurs de l'exposition professionnelle à l'amiante ou à la silice cristalline. / Introduction: The objective of this thesis was to study the association between tobacco smoking and occupational exposure to asbestos and crystalline silica with the phenotypes of lung cancer. The second objective was to assess the effect modification of the association between tobacco smoking and the phenotypes of lung cancer by occupational exposure to asbestos or to crystalline silica. Methods : The CaProMat study is a pooled retrospective case-only study consisted of9,623 French and Canadian lung cancer cases. All lung cancer cases were histologically confirmed. Data were collected from medical records and through standardized questionnaires. Two job-exposure matrices (JEMs) were used to assess the occupational exposure to asbestos and to crystalline silica. Results: We did not identify a difference of prevalence of occupational exposure to asbestos according to histological type. For crystalline silica, a borderline excess of prevalence of exposure was observed for squamous cell carcinoma. The prevalence of occupational exposure was maximized among lung cancer cases diagnosed between 50 and 59 years for asbestos and less than 50 years for crystalline silica. Additional exposure to either asbestos or crystalline silica did not modify the effect of tobacco smoking for histological type, tumor location or age at diagnosis. Conclusions: The histological type, tumor location, and age at diagnosis cannot beused as an indicator for the occupational exposure to asbestos or to crystalline silica.