Silicosis Appears Inevitable Among Former Denim Sandblasters: A 4-Year Follow-up Study

Abstract

Background: The course of denim sandblasting silicosis is unknown. We aimed to reevaluate former sandblasters studied in 2007 for incident silicosis, radiographic progression, pulmonary function loss, and mortality and to examine any associations between these outcomes and previously demonstrated risk factors for silicosis.

Methods: We defined silicosis on chest radiograph as category 1/0 small opacity profusion using the International Labor Organization classification. We defined radiographic progression as a profusion increase of two or more subcategories, development of a new large opacity, or an increase in large opacity category. We defined pulmonary function loss as a ≥ 12% decrease in FVC.

Results: Among the 145 former sandblasters studied in 2007, 83 were reassessed in 2011. In the 4-year follow-up period, nine (6.2%) had died at a mean age of 24 years. Of the 74 living sandblasters available for reexamination, the prevalence of silicosis increased from 55.4% to 95.9%. Radiographic progression, observed in 82%, was associated with younger age, never smoking, foreman work, and sleeping at the workplace. Pulmonary function loss, seen in 66%, was positively associated with never smoking and higher initial FVC % predicted. Death was associated with never smoking, foreman work, number of different denim-sandblasting places of work, sleeping at the workplace, and lower pulmonary function, of which only the number of different places worked remained in multivariate analyses.

Conclusions: This 4-year follow-up suggests that almost all former denim sandblasters may develop silicosis, despite short exposures and latency.

Figure 1 –

Flowchart. The 83 former sandblasters reported in the current study included 74 living participants who had new chest radiographs and pulmonary function tests in 2011 and nine who were deceased.

Figure 2 –

A-C, Chest radiographs showing progression in three different cases. A, Incident small opacities to International Labor Organization subcategory 3/2. B, Incident small opacities to category C large opacity. C, Progression of large opacities from category A to category B.

Figure 3 –

Radiographic progression during the follow-up period by individual participants showing International Labor Organization small-opacity profusion and large-opacity category on the vertical axis. Large-opacity categories A, B, and C are indicated by bars of lengths 1, 2, and 3 units, respectively. Decedents are indicated in the top row on top of the appropriate histogram bar.

Figure 4 –

Pulmonary functions (FVC % predicted values) by individual participants in the study group, with the same numbering system as used in Figure 3. Light gray bars indicate the 2007 value for decedents, indicated in the top row above the appropriate histogram bar. Hatched bars indicate a 2011 increase in the 2007 value. Dark gray bars indicate the magnitude of decrease of pulmonary function in 2011 compared with the 2007 value, the latter being the sum of light gray and dark gray bars.