Assessment of hazardous dust exposure by BAL and induced sputum

Objectives: BAL, an important tool in assessing occupational lung diseases, is unsuitable for screening programs, exposure evaluation, or monitoring hazardous dust because it is an invasive technique. The results of induced sputum (IS) analysis were compared with BAL and evaluated as a possible alternative. Methods: We compared BAL with IS analysis of 5 workers exposed to asbestos and 14 exposed to silica and hard metals. Pulmonary function tests and BAL were performed by conventional methods. IS induction was performed after a 20-min inhalation of 3.5% saline solution with an ultrasonic nebulizer. Giemsa-stained cytopreparations were differentially counted. T-lymphocyte subsets were analyzed by flow-activated cell sorter, and messenger RNA (mRNA) was transcribed by reverse transcriptase-polymerase chain reaction. Mineralogic particles were analyzed by scanning electron microscopy and polarizing light microscopy and quantified by an analyzer. Results: The percentage of neutrophils was significantly lower in BAL fluid than in IS specimens, whereas no differences were found in the percentage of lymphocytes and subsets profile. Asbestos fibers were found in BAL but not in IS samples from workers exposed to asbestos. Polarizing particles were found in both samples. Similar mineral elements were found in qualitative analysis by scanning electron microscopy. Quantitative studies showed similar size distribution with a small shift toward larger particles in sputum; mRNA showed the same cytokine profile. Conclusions: A comparison of BAL and IS specimens in the evaluation of the study population yielded similar quantitative and qualitative results. Further research is needed to evaluate the hypothesis that IS, being a noninvasive technique, may be useful in monitoring exposed workers.