[Exposition markers: mineralogical analysis in the sputum and the bronchoalveolar lavage--asbestos bodies--uncoated fibres].

The aim of mineralogical analysis of lung tissue, bronchoalveolar lavage (BAL) and sputum is to characterize individuals' exposure to asbestos fibres by identifying markers of this; asbestos bodies (AB) and uncoated fibres. The techniques of mineralogical analysis, habitually used to identify AB and uncoated fibres, are respectively optical microscopy (OM) and analytical electronic microscopy (EM). Correlations between levels of retention of AB in lung tissue, BAL and sputum have been established and validated threshold values indicating a high probability of significant exposure exist. These results must be interpreted in the context of clinical and occupational information. Mineralogical analysis is not suitable for use in routine medical screening but it can be considered when a source of exposure is not evident from the questionnaire since a positive analysis of BAL or of sputum is highly specific and thus useful to confirm an important retention of asbestos in the lung, which justifies medical follow-up. A negative result does not exclude previous significant asbestos exposure (frequent false negatives occur especially in sputum and biopersistence of chrysotile is lower than for amphiboles). Thus it can be a complementary tool for the assessment of asbestos exposure but its use imposes conditions for the collection and handling of samples.