Mineral fiber analysis and assessment of past exposure to asbestos.

Despite intrinsic limitations due to differences in the biopersistence of t he various asbestos types, in the definition of control populations and in analytical techniques used by the laboratories, mineralogical analysis of b iological samples is useful ill the assessment of past exposure to asbestos . It provides additional information to occupational and environmental ques tionnaires, particularly when exposure to asbestos is doubtful, unknown or forgotten by a subject. Results should be interpreted taking into account c linical information. A positive result does not mean existence of asbestos- related disease. A negative result does not exclude previous significant as bestos exposure, clearly identified by an occupational questionnaire (parti cularly for exposure to chrysotile). Threshold values indicative of a high probability of previous asbestos exposure have been established for broncho alveolar lavage fluid (BALF) samples and lung tissue samples. Quantificatio n of asbestos bodies by light microscopy is easy to perform. Sensitivity an d specificity of this analysis towards the total pulmonary asbestos fiber b urden is good Therefore this analysis should be performed first Mineralogic al analysis in BALF or lung tissue should be considered only when sampling is supported by diagnostic or therapeutic implications.