The impact of occupational exposure to crystalline silica dust on respiratory function (airway obstruction and FEF) in the French general population.

Introduction: Although several studies have studied the relationship between occupational exposure to crystalline silica dust and respiratory mortality, few have examined the relationship with impairments in respiratory function and the exposure threshold triggering spirometric monitoring in exposed workers. The objective of the present study was to evaluate the impact of exposure to crystalline silica dust on respiratory function.

Methods: We included 1428 male participants (aged 40 to 65) recruited from the French general population, at random from electoral rolls, in the cross-sectional ELISABET study and for whom data on forced expiratory flow-volume curve indices z-scores (calculated using the Global Lung Function Initiative 2012 equations) and exposure (via a questionnaire) were available. A cumulative exposure index (CEI) for crystalline silica dust (CEI, expressed in mg.m.year) was calculated using the Matgéné occupational exposure matrix.

Results: 293 of the 1428 participants (20.52%) reported exposure to silica dust. We found that the adjusted z-scores for the forced expiratory volume in the first second/forced vital capacity (FEV/FVC) ratio decreased significantly as CEI increased. After adjustment, the adjusted z-scores for FEV/FVC (β: -0.426 (95% confidence interval (CI): -0.792, -0.060) per 1 mg m.year increment) and the mean forced expiratory flow between 25 and 75% of the forced vital capacity (FEF) (β: -0.552 (95% CI: -0.947, -0.157)) were significantly lower in the participants with CEI ≥1 mg m.year than in non-exposed participants. The likelihoods of having airway obstruction (odds ratio (OR): 3.056 (95% CI: 1.107, 7.626)) or having an impaired FEF (OR: 4.305 (95% CI: 1.393, 11.79)) were also significantly higher in participants with CEI ≥1 mg m.year.

Conclusion: Our results emphasize the importance of spirometry-based monitoring in workers exposed to more than 1 mg m.year of crystalline silica dust, in order to identify small airway obstruction or airway obstruction as early as possible.