Mining Tenure and Job Duties Differ Among Contemporary and Historic Underground Coal Miners With Progressive Massive Fibrosis

Objective: To characterize differences in mining jobs and tenure between contemporary (born 1930+, working primarily with modern mining technologies) and historic coal miners with progressive massive fibrosis (PMF). Methods: We classified jobs as designated occupations (DOs) and non-DOs based on regulatory sampling requirements. Demographic, occupational characteristics, and histopathological PMF type were compared between groups. Results: Contemporary miners (n = 33) had significantly shorter mean total ( 30.4 years vs 37.1 years, P = 0.0006) and underground (28.8 years vs 35.8 years, P = 0.001) mining tenure compared with historic miners (n = 289). Silica-type PMF was significantly more common among miners in non-DOs (30.1% vs 15.8%, P = 0.03) and contemporary miners (58.1% vs 15.2%, P < 0.0001). Conclusions: Primary jobs changed over time with the introduction of modern mining technologies and likely changed exposures for workers. Elevated crystalline silica exposures are likely in non-DOs and require attention.