RESPIRATORY IMPAIRMENTS DUE TO DUST EXPOSURE - A COMPARATIVE-STUDY AMONG WORKERS EXPOSED TO SILICA, ASBESTOS, AND COALMINE DUST

We conducted a comparative study of pulmonary dysfunction among worker s who were exposed to silica, asbestos, or coalmine dust. The results showed that all three groups of dust-exposed workers, even those witho ut radiographic signs of pneumoconiosis, had decreased spirometric par ameters and diffusing capacity (DLco) in both nonsmokers and smokers. Pulmonary function was further decreased when pneumoconioses were pres ent in the three groups. In accord with increasing radiographic catego ries, pulmonary function in the workers with either silicosis or asbes tosis was even lower, whereas in those with coal workers' pneumoconios is (CWP), if changed relatively little. Workers with mild to moderate (radiographic category I-II) silicosis or asbestosis showed similarly decreased DLco, but those with silicosis showed lower FEV(1)/FVC than those with asbestosis. The workers with CWP also showed a lower FEV(1) /FVC than those with asbestosis. The major impairment patterns for sil ica workers, asbestos workers, and coal miners were mixed, restrictive and mixed, and obstructive, respectively. Smoking obviously increased the prevalence of obstruction for all the groups. We conclude from th e present study that all the three dusts cause functional abnormalitie s that precede radiographic changes of pneumoconiosis. We should pay m ore attention to respiratory impairment in the initial stage of silico sis and CWP. (C) 1997 Wiley-Liss, Inc.