Occupational exposures and risk of pulmonary alveolar proteinosis (PAP)

Occupational exposures to dust have been associated with pulmonary alveolar proteinosis (PAP) in case series, but population-based epidemiological data are needed.

We identified 286 cases of PAP from the Swedish National Patient Register and the Cause-of-Death Register between 1991 and 2022. For the present analysis, we included 212 cases aged 20-65 years with available occupational information before the index date or within two years thereafter. Controls matched on age and sex were drawn from the population register and assigned the same index date as their corresponding case; of these, 1438 controls had available occupational information and were included in the analyses. We linked cases and controls to Swedish registries to obtain socioeconomic status and occupational data. We applied an established job-exposure matrix to characterize occupational exposure to inorganic dust, with the subset silica dust, fumes, vapors and gases and organic dust. We used adjusted conditional logistic analyses to estimate the odds ratios (OR) with 95% confidence intervals (CI) for the occupational exposures in the year before index date and PAP.

None of the occupational exposures analyzed showed a statistically significant association to PAP. The OR for inorganic dust was 1.08 (95% CI 0.75-1.55); silica dust alone was 1.55 (95% CI 0.75-3.23) and organic dust was 1.48 (95% CI 0.92-2.38). Among men, however, exposure to organic dust was associated with PAP [OR 1.92 (95% CI 1.18-3.23)]. Among women, the results were inconclusive.

There were no associations between occupational exposure to fumes, vapors and gases and inorganic dust and risk of PAP. Among men, exposure to organic dust was associated with increased risk for PAP. Some occupational inhalants may increase the risk of PAP.