To determine the associations between exposure duration, measured by employment tenure, and emphysema presence and severity in black and white South African miners at autopsy.
We examined the association between mining tenure and emphysema presence or severity using the Pathology Automation (PATHAUT) database, 1975-2014. We used logistic regression models adjusted for age, tuberculosis, HIV status, and year of death. The effect of smoking on the presence and severity of emphysema was assessed in a sub-analysis of white miners.
Mining tenure was significantly associated with increased odds of emphysema presence in black and white miners. For every 10-year increase in tenure, black miners had a 17% increase in odds of emphysema [ORblack = 1.17 (95% CI 1.12, 1.22)] and white miners had a 7% increase in odds of the disease [ORwhite = 1.07 (95% CI 1.04, 1.10)]. Tenure was significantly associated with emphysema severity among black miners [ORseverity = 1.16 (95% CI 1.06, 1.28)]. In a subset of white miners with smoking status, we found that for every 10 years of tenure, there is a significant increase in odds of emphysema presence and severity [ORpresence = 1.14 (95% CI 1.09, 1.19); ORseverity = 1.06 (95% CI 1.00, 1.10)] after adjusting for smoking.
We observed a significant relationship between mining tenure and emphysema severity among South African miners in PATHAUT between 1975 and 2014. This relationship was evident in multi-variable analyses adjusted for smoking among white miners. Hazards from long term exposure to inhaled mineral dust leading to lung damage (silicosis, fibrosis, COPD) is evident and warrants further improvement of working conditions and prevention measures in South African mines especially for black workers. Further research is needed to determine if there is an effect of TB and HIV co-infection on the development of emphysema.