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. 2024 Jul 10;81(6):279-286.
doi: 10.1136/oemed-2023-108964.

Occupational exposure to respirable crystalline silica and incident idiopathic interstitial pneumonias and pulmonary sarcoidosis: a national prospective follow-up study

Inge Brosbøl Iversen  1 , Jesper Medom Vestergaard  2 , Johan Ohlander  3 , Susan Peters  3 , Elisabeth Bendstrup  4 , Jens Peter Ellekilde Bonde  5 , Vivi Schlünssen  6 , Jakob Hjort Bønløkke  7 , Finn Rasmussen  8 , Zara Ann Stokholm  2 , Michael Brun Andersen  9   10 , Hans Kromhout  3 , Henrik Albert Kolstad  2   11
Affiliations

Occupational exposure to respirable crystalline silica and incident idiopathic interstitial pneumonias and pulmonary sarcoidosis: a national prospective follow-up study

Inge Brosbøl Iversen et al. Occup Environ Med. .

Abstract

Background: Respirable crystalline silica is a well-known cause of silicosis but may also be associated with other types of interstitial lung disease. We examined the associations between occupational exposure to respirable crystalline silica and the risk of idiopathic interstitial pneumonias, pulmonary sarcoidosis and silicosis.

Methods: The total Danish working population was followed 1977-2015. Annual individual exposure to respirable crystalline silica was estimated using a quantitative job exposure matrix. Cases were identified in the Danish National Patient Register. We conducted adjusted analyses of exposure-response relations between cumulative silica exposure and other exposure metrics and idiopathic interstitial pneumonias, pulmonary sarcoidosis and silicosis.

Results: Mean cumulative exposure was 125 µg/m3-years among exposed workers. We observed increasing incidence rate ratios with increasing cumulative silica exposure for idiopathic interstitial pneumonias, pulmonary sarcoidosis and silicosis. For idiopathic interstitial pneumonias and pulmonary sarcoidosis, trends per 50 µg/m3-years were 1.03 (95% CI 1.02 to 1.03) and 1.06 (95% CI 1.04 to 1.07), respectively. For silicosis, we observed the well-known exposure-response relation with a trend per 50 µg/m3-years of 1.20 (95% CI 1.17 to 1.23).

Conclusion: This study suggests that silica inhalation may be related to pulmonary sarcoidosis and idiopathic interstitial pneumonias, though these findings may to some extent be explained by diagnostic misclassification. The observed exposure-response relations for silicosis at lower cumulative exposure levels than previously reported need to be corroborated in analyses that address the limitations of this study.

Keywords: Lung Diseases, Interstitial; Occupational Health; Silicosis.

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Conflict of interest statement

Competing interests: EB has received payment for lectures from Daiichi-Sankyo, Boehringer Ingelheim, AstraZeneca and Hoffmann-la-Roche and support for attending meetings from Boehringer Ingelheim. VS has been Chair of the Danish Quality Committee for Occupational Exposure Limits of the Danish Working Environment Authority from 2016 to 30 June 2022. MBA has received grants from the Danish Center for Lung Cancer Research, Innovation Fund Denmark and AI Signature funds from the Danish government and has received payment for lectures from Boehringer Ingelheim. HK has received a grant from Industrial Minerals Association Europe for managing the IMA-DUST Monitoring Programme. HK and SP are Editorial Board members of Occupational and Environmental Medicine. All other authors have nothing to disclose.

Figures

Figure 1
Figure 1
Restricted cubic spline fits of adjusted incidence rate ratios of idiopathic interstitial pneumonias, pulmonary sarcoidosis and silicosis by cumulative respirable crystalline silica. Dotted lines mark 95% CIs.
See this image and copyright information in PMC

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