Respiratory symptoms and lung function in bauxite miners

Objectives: To determine whether cumulative bauxite exposure is associated with respiratory symptoms or changes in lung function in a group of bauxite miners. Methods: Current employees at three bauxite mines in Australia were invited to participate in a survey comprising: questionnaire on demographic details, respiratory symptoms, and work history; skin prick tests for four common aeroallergens; and spirometry. A task exposure matrix was constructed for bauxite exposure in all tasks in all jobs based on monitoring data. Data were examined for associations between cumulative bauxite exposure, and respiratory symptoms and lung function, by regression analyses. Results: The participation rate was 86%. Self-reported work-related respiratory symptoms were reported by relatively few subjects (1.5%-11.8%). After adjustment for age and smoking no significant differences in the prevalence of respiratory symptoms were identified between subjects, in the quartiles of cumulative bauxite exposure distribution. The forced expiratory volume in 1 s (FEV1) of the exposed group was found to be significantly lower than that for the unexposed group. After adjustment for age, height, and smoking there were no statistically significant differences between quartiles in FEV1, forced vital capacity (FVC) and FEV1/FVC ratio. Conclusions: These data provide little evidence of a serious adverse effect on respiratory health associated with exposure to bauxite in an open-cut bauxite mine in present day conditions.