Airflow obstruction in nonsmoking, asbestos-and mixed dust-exposed workers

Abstract

Obstructive changes in small airways have been described in patients exposed to asbestos and other mineral dusts. The physiologic significance of these small airways abnormalities and their relationship to dust burden and alveolitis remain unclear. We performed bronchoalveolar lavage (BAL) in 30 nonsmoking and 30 age-matched smoking subjects, all with mild asbestos and mixed dust exposure, to determine if parameters of lung dust burden correlated with spirometric evidence of airflow obstruction. Seventeen of 30 nonsmoking subjects and 24 of 30 smoking subjects met spirometric criteria for airflow obstruction. There were significantly more obstructed subjects in both dust exposed groups (P < 0.05) than in an age-matched nondust exposed group. There was, however, no significant difference in the number of obstructed subjects between the smoking and nonsmoking groups. There was no correlation in either group between airflow obstruction and total or differential cell counts, ferruginous bodies, total asbestos fibers, or the percent of free silica in the particulate fraction recovered by BAL. We conclude that evidence of small airways obstruction occurs commonly in occupationally dust exposed subjects and appears to be related to dust exposure per se and not to alveolar inflammation or fiber retention, important factors in the development of alveolitis and interstitial lung disease.

Nonmalignant Asbestos-Related Disease: Diagnosis and Early Management

“…37,38 A small effect has been observed in lifelong nonsmokers. 22,30,39 This effect begins in small airways, consistent with the known pathology of bronchiolitis in early asbestosis. 39,40 Histologically, inflammation and airway fibrosis characterize asbestos-related small airways disease, and the histology is somewhat different from the lesion of cigarette smoking.…”

Patterns of pulmonary dysfunction in asbestos workers: a cross-sectional study

“…Similarly, Begin found evidence of diminished flows at low lung volumes in non-smoking chrysotile workers [20], and Becklake observed an obstructive pattern of reduction in spirometry in groups with high dust exposure[21]. Later, Griffith et al demonstrated airway disease in a non-smoking cohort of asbestos workers [22]. Kilburn and Warshaw observed a reduction in FEV1, FEV1/FVC ratio, and an increase in RV/TLC, an obstructive pattern [23].…”

“…Furthermore, in most of the studies, especially those conducted before the mid-nineties, either small sample size and/or the effect of smoking were limitations making interpretation difficult. Other areas of concern in most of the studies included the use of FEF, a less stable measure of obstruction[12,22,33,36], incomparable or absent control groups, [18,23,32], lack of DLCO measurement [32,33], single chest -x-ray reader [23], and use of unadjusted FEV1/FVC and RV/TLC ratios[23]. To provide additional information, we compared the pattern of pulmonary dysfunction in asbestos workers using spirometric and DLCO measurements in a relatively large groups of chrysotile exposed subjects and controls without asbestos exposure.…”

Bronchiolitis obliterans in an animal feed worker

“…Griffith et al [1993] reported no correlation between the degree of small airway airflow obstruction and the percent of free silica in the particulate fraction of the bronchoalveolar lavage fluid specimens from dust-exposed subjects. These studies suggest that whereas silica exposure may indeed cause airflow obstruction in the small airways, the degree of exposure required to produced obstruction in an individual patient as well as the necessary latency period is not clear (most involved workers had at least several years of dust exposure).…”