Asbestos content of bronchoalveolar lavage fluid. A comparison of light and scanning electron microscopic analysis

We studied the asbestos content of bronchoalveolar lavage fluid (BALF) from 9 patients with asbestosis, 17 asbestos exposed but without asbestosis, 15 with idiopathic pulmonary fibrosis (IPF) and 9 nonexposed volunteers. The cellular lavage pellet was digested and filtered for asbestos body (AB) quantification by light microscopy (LM) and analysis of numbers and types of uncoated fibers (UF) by scanning electron microscopy (SEM) and energy dispersive x-ray analysis. BALF of asbestosis patients had significantly higher AB content than that of the combined IPF and volunteer groups. The UF content as determined by SEM was similar in all four groups. Commercial amphiboles (amosite or crocidolite) were identified more frequently in BALF from patients with asbestosis than from the other groups. ABs were detected by SEM only in highly exposed individuals. We conclude that the findings of > 1 AB per 10(6) cells or 1 AB/mL BALF by LM and of ABs or commercial amphibole fibers by SEM are indicative of considerable exposure to asbestos in the majority of cases.