Lung Diseases in South African and United States Miners

Objective: The objectives of this study were to; 1)determine association between mining tenure and emphysema among South African miners, 2) investigate the association between mining commodities and emphysema presence or severity and 3) assess the association between mining occupation categories and obstructive lung disease in the U.S. Methods: Association between mining tenure and emphysema presence or severity was determined using Pathology Automation database, 1975 − 2014. Logistic regression models adjusted for age, tuberculosis, AIDS-related diseases, and year of death were used. Smoking was assessed in a sub-analysis of white miners. To determine association between mining commodity and emphysema presence or severity, multivariable logistic regression models controlling for mining tenure, age, tuberculosis, AIDS-related diseases, and year of death were used. Data from the National Health Interview Survey (NHIS), 2006-2015 was used to determine the relationship between specific mining occupations and a diagnosis of obstructive lung disease. We classified occupations into low, mid, high, and dust exposure groups. Survey logistic regression models were used to evaluate possible associations between occupation and diagnoses of chronic bronchitis, emphysema, COPD, and asthma. Results: In South African miners at autopsy, mining tenure was associated with emphysema presence in both black and white miners [ORblack (10 years) = 1.17 (95%CI: 1.12, 1.22); ORwhite (10 years) = 1.07 (95%CI: 1.04, 1.10)] and with emphysema severity among black miners [ORseverity (10 years) = 1.16 (95%CI: 1.06, 1.28)]. Controlling for smoking, 10-year exposure and emphysema were associated among whites [ORpresence = 1.14 (95%CI: 1.09, 1.19); ORseverity = 1.06(95%CI: 1.00, 1.10)]. In fully adjusted models, compared to gold mining in South Africa, coal mining was associated with increased odds of emphysema presence and severity in blacks [ORpresence = 2.52 (95%CI: 2.25, 2.83); ORseverity = 2.50 (95%CI: 1.90, 3.28)]. Diamond mining was also associated with emphysema presence and severity among black miners [ORpresence = 1.78 (95%CI: 1.17, 2.71); ORseverity = 2.83 (95%CI: 1.20, 6.68)]. No significant differences in odds of emphysema were observed in white miners. In U.S. miners, we found 4.5% of miners had a diagnosis of chronic bronchitis, 3.3% had emphysema 6.2% had COPD, and 9.9 % had asthma. Fully adjusted models showed that mining extraction workers had significantly increased odds of chronic obstructive diseases including chronic bronchitis [OR = 2.18 (95%CI: 1.02, 4.64)], emphysema [OR = 7.85 (95%CI: 1.70, 36.27)], and COPD [OR = 2.56 (95% CI: 1.29, 5.12)] compared to lower exposure occupations. Conclusions: Among both black and white South African miners, there was an observed association between mining tenure and odds of developing emphysema, although the relationship was stronger among black miners. There is also a strong association between coal mining with emphysema presence or severity among black miners in the region. Using a U.S. database, we show evidence that occupation is an important predictor of obstructive lung disease in the mining industry.