Environmental dust exposure from gold mine dumps and chronic respiratory conditions

Abstract

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.