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This lecture deals with pneumoconiosis, in particular with fibrotic tissue reactions caused by SiO2 and asbestos dusts in the lungs. The term "fine dusts" is defined in connection with the setting up of MAC-values. The aerodynamical diameter of particle shaped and fibrifom dust is set forth. Results of the fundamental research with SiO2, Coal mine and asbestos dusts in animal and cell experiments are explained.
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PMID:1975 Yant Memorial Lecture New aspects on dust and pneumoconiosis research. 17 Aug 15

Exposure to dust mixture containing at the same time respirable mineral fibres and free crystalline silica may occur in Poland in mines and in the Lower Silesia plants processing mineral raw materials as well as in all plants which use asbestos products and MMMF. Workposts where thermal insulation is exchange with possible phase transformations during operations under conditions of high temperature, expose particularly complex problems. In the work environment of this kind, dust concentration of free crystalline silica becomes important but not sufficient criterion for evaluating working conditions and it may be misleading. A range of studies indispensable for the proper evaluation of exposure to dust, covering together with measurement of dust and SiO2 concentrations, determination of the mineral composition of dust, was developed. It was also found that the acceptable level of risk for neoplastic disease, namely 10(-3) can be attained in the work environment only if the concentration ranges from 0.05 to 0.1 f/cm3, that is equal to 20% of MAC value which is now binding in Poland. Cancer risk (lung cancer and mesothelioma jointly) during a 20-year exposure to concentrations equal to present MAC values should be estimated as about 10(-2) what indicates that risk is too high and it is necessary to diminish MAC values for asbestos dust.
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PMID:[Exposure to dust mixtures containing free crystalline silica and mineral fibers]. 865 99

An appropriate evaluation of exposure to dust containing both crystalline silica and asbestos (e.g., some mines of rock materials, installation and disassembly of thermal insulation and frictional products etc.) requires that the presence of these two potentially carcinogenic dust components should be taken into account. In Poland, the present legal regulations provide for rather extensive freedom in both defining the scope of studies performed and interpreting their results. In consequences, the evaluation of dust exposure at similar workposts in different plant is based on different criteria, which means that in some cases the presence of free crystalline silica (MAC value for dust containing from 2 to 50% of SiO2--is 4 mg/m3 for total dust and 1 mg/m3 for respirable dust) is taken into account, and in others the presence of mineral fibers such as chrysotile and other fibrous mineral except for crocidolite (MAC value--1 mg/m3 and 0.2 f/cm3, respectively). The evaluation of exposure usually involves only one factor, i.e. free silica crystalline (more favorable for the administration of a given plant). The present study reveals that depending on the criterion adopted for evaluating the exposure at a given workpost (e.g. exchange of thermal insulation), the working conditions may be classified as safe (criterion for the presence of SiO2) or as harmful to workers' health if a complete composition of mineral dust (chrysotile, amosite, quartz) is considered. In order to clarify the present situation, the authors present in this paper the proposals on the scope of required studies (measurements of total and respirable dust, as well as respirable mineral fibers concentrations, determination of SiO2 contents, identification of dust crystalline phases) and the principles on which the interpretation of results should be based.
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PMID:[Evaluation of occupational exposure to dusts of mixed free crystalline silica and natural respirable mineral fibers]. 1236 4