Risk of hypersensitivity pneumonitis and other interstitial lung diseases following organic dust exposure.

Background: Organic dust is associated with hypersensitivity pneumonitis, and associations with other types of interstitial lung disease (ILD) have been suggested. We examined the association between occupational organic dust exposure and hypersensitivity pneumonitis and other ILDs in a cohort study.
Methods: The study population included all residents of Denmark born in 1956 or later with at least 1 year of gainful employment since 1976. Incident cases of hypersensitivity pneumonitis and other ILDs were identified in the Danish National Patient Register 1994-2015. Job exposure matrices were used to assign individual annual levels of exposure to organic dust, endotoxin and wood dust from 1976 to 2015. We analysed exposure-response relations by different exposure metrics using a discrete-time hazard model.
Results: For organic dust, we observed increasing risk with increasing cumulative exposure with incidence rate ratios (IRR) per 10 unit-years of 1.19 (95% CI 1.12 to 1.27) for hypersensitivity pneumonitis and 1.04 (95% CI 1.02 to 1.06) for other ILDs. We found increasing risk with increasing cumulative endotoxin exposure for hypersensitivity pneumonitis and other ILDs with IRRs per 5000 endotoxin units/m ³ -years of 1.55 (95% CI 1.38 to 1.73) and 1.09 (95% CI 1.00 to 1.19), respectively. For both exposures, risk also increased with increasing duration of exposure and recent exposure. No increased risks were observed for wood dust exposure.
Conclusion: Exposure-response relations were observed between organic dust and endotoxin exposure and hypersensitivity pneumonitis and other ILDs, with lower risk estimates for the latter. The findings indicate that organic dust should be considered a possible cause of any ILD.
Trial Registration Number: j.no.: 1-16-02-196-17.
Competing Interests: 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. All other authors have nothing to disclose.
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