par Dumortier, Pascal ;De Vuyst, Paul
Référence XIVth International Clay Conference (June 14-20,2009: Castellaneta (Italy))
Publication Non publié, 2009
Communication à un colloque
Résumé : Respirable particles from environmental or occupational air pollution are continuously inhaled and part of them is retained in the lungs over time. Accumulated particles may induce various respiratory diseases (pneumoconiosis, lung granulomatosis, alveolar proteinosis,..). Most of these diseases are dose related. Since it is often difficult to obtain a thorough exposure history from the patients, mineralogical analysis of the particles recovered from their lungs can be used to get individual estimates of previous exposures. Compared to the numerous studies about asbestos burden in lungs, systematic data about the non-fibrous mineral particles (NFPs) contained in lung samples (bronchoalveolar lavage fluids (BAL) or lung tissue (LT)) are currently scarce. This is perhaps due to the complexity and diversity of the analytical methods (light and electron microscopy, x-ray diffraction) required to analyse particles in the submicron range and to the lack of specific markers for routine analysis. Other obstacles are the variety of particles to be analysed and the existence of a background burden of NFPs in the lungs of everyone which may interfere with the particles directly related to the exposure or disease under investigation. Our experience with NFPs analysis will be summarized and compared to the data available from the literature. From one to over 20 different particle types can be detected in lung samples by analytical transmission electron microscopy. The most frequent are silica, silicates (including clay minerals), iron compounds and titanium oxide. Particle sizes are log normally distributed. Geometric mean diameter range from 0.21 to 1.13 µm. Considering the influence of particle type on particle size, the following gradation can be established; Ø metallic compounds < Ø non lamellar silicates (silica, feldspar, siliceous flyash,...) < Ø lamellar silicates (kaolinite, illite, mica, talc, chlorite). NFPs concentrations range from X*104 to 107 P/ml in BAL and from 109 to 1010 P/gm dry tissue in LT. Reference levels are obtained by analysing samples for individuals without particular dust exposures. An “abnormal” result can help to confirm the diagnosis of a suspected particle-induced lung disease. In the absence of detectable disease an abnormal mineralogical analysis result is in no way a proof of disease. Nevertheless, these individual situations need a follow up, since the probability of developing a pathological reaction to inhaled dusts increases with time. The absence of mineralogical abnormalities is an argument against particle-induced lung disease and further investigations are needed to obtain a diagnosis. By helping to the etiological diagnosis of a lung disease, these analyses may have clinical implications in case treatment is available and social benefit if disease can be compensated