Environmental dust exposure from gold mine dumps and chronic respiratory conditions

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2019

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Iyaloo, Samantha

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Background: People living in close proximity to gold mine waste dumps are exposed to wind-3 borne, silica-rich dust. The effects on respiratory heath consequent on this exposure are largely 4 unknown. 5 Objective: To examine associations between environmental gold mine dump dust exposure and 6 respiratory health in adults. 7 Methods: A cross-sectional study was done with 93, 133 and 84 people in high (home < 500m 8 from a mine dump), moderate (500m-1.5km) and low (> 15km) exposure groups respectively. We 9 calculated a cumulative exposure index (CEI) based on exposure groups and years of residence in 10 them. Participants were interviewed about respiratory symptoms, had chest X-rays and 11 spirometry. We used multivariate logistic regression to examine the effect of dust exposure on 12 respiratory symptoms and conditions, and multiple linear regression to determine if CEI was 13 associated with percentage predicted FEV1 and FVC. We adjusted for socioeconomic status, 14 smoking, biomass fuel use and occupational exposure. 15 Results: No participant had radiological features of silicosis. The high relative to the low exposure 16 group had significantly elevated adjusted odds ratios (aORs) for upper respiratory symptoms 17 (aOR: 2.76, 95% CI: 1.28, 5.97), chest wheezing (aOR: 3.78; 95% CI: 1.60, 8.96) and spirometry-18 diagnosed COPD (aOR: 8.17; 95%CI: 1.01, 65.85). These findings were similar for the high relative 19 to medium exposure group, but no significant associations were found for the medium versus 20 low exposure group. Chronic bronchitis and tuberculosis risks did not differ significantly among 21 the groups. Using CEI to estimate exposure produced similar results. Linear regression showed 22 that CEI was not associated with % predicted FEV1, but, surprisingly, FVC% was positively 23 associated with the index. 24 Conclusions: Residents residing < 500m from mine dumps had elevated risks of respiratory 25 symptoms and COPD, but there was no evidence of a negative association between FEV1 or FVC 26 and mine dump dust exposure.

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A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Medicine in Community Health (Occupational Medicine)

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