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 : Use of asbestos is now banned in many industrialized countries, but health consequences are still expected for at least two decades. Moreover, exposure to asbestos currently continues in several emerging countries. Asbestos-related diseases are usually the consequence of occupational exposures, but cases occurring from para-occupational, bystander or intra-mural exposures were also reported. In rural areas of several countries, fibres naturally occurring in local soils are responsible for a high incidence of asbestos diseases. Health effects of asbestos include malignant and non-malignant lesions of the lung and pleura, and more rarely peritoneum. It is often necessary to assess past exposures to asbestos for clinical, epidemiological, occupational health or even legal purposes. The difficulties and uncertainties associated with the use of occupational histories, job exposure matrixes or calculations from specific exposure databases have led to investigate the capabilities of fiber analysis in lung samples. Key points related to this topic will be reviewed here. Guidelines about technical aspects of fiber analysis and rules to interpret results were published by a workgroup of the European Respiratory Society (1). Evidence of exposure can be obtained by demonstrating elevated levels of asbestos bodies or fibres by light or electron microscopy in samples of lung tissue, bronchoalveolar lavage fluid or sputum. Relevant data are sought about the fiber types present, their amounts, their sizes, composition and crystalline structure and about their importance as aetiological agent. The measured fiber burdens integrate both phenomena of lung deposition and clearance. Compared to amphibole asbestos, chrysotile has a much lower biopersistance and evaluation of past exposures to this variety of asbestos by analysing lung samples is difficult. Interestingly, chrysotile elementary fibrils are morphologically similar to sepiolite and attapulgite fibrils. There are different dose-response relationships between lung parenchyma and pleura in response to asbestos exposure. The highest cumulative exposures and hence pulmonary asbestos bodies and fibres levels are found in asbestosis. Lower levels, corresponding sometimes to very low cumulated exposure, are usually expected in mesothelioma and in pleural plaques. However, it must be stressed that bronchoalveolar lavage fluid and lung tissue analyses are markers of alveolar and parenchymal retention of fibres, but do not reflect directly the accumulation of fibres in the parietal pleura which is very heterogeneous. (1) De Vuyst P, Karjalainen A, Dumortier P, Pairon JC, Monso E, Brochard P, Teschler H, Tossavainen A, Gibbs A (1998). Guidelines for mineral fibre analyses in biological samples: report of the ERS Working Group. European Respiratory Society. Eur Respir J;11:1416-1126.