EFFECTS OF ASBESTOS AND SMOKING ON THE LEVELS AND RATES OF CHANGE OF LUNG FUNCTION IN A CROCIDOLITE-EXPOSED COHORT FROM WITTENOOM, WESTERN AUSTRALIA

Abstract

Objective To examine the effects of asbestos and smoking exposure on the level and rate of change of lung function in former workers and residents exposed to crocidolite at Wittenoom, Western Australia, who have participated in a chemoprevention program using vitamin A. Methods Using a liner mixed-effects model, we evaluated the effects of crocidolite exposure and smoking history at the first visit and longitudinally, controlling for potential confounders. Lung function was measured as forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and FEV1/FVC. Results There were 835 former workers and 582 former residents. Higher cumulative doses of asbestos and the presence of radiographic asbestosis were associated with lower levels of FEV1 and FVC at the first visit, and a steeper decline during the follow up period. Subjects exposed to asbestos at a younger age had lower levels of FEV1 and FVC at first visit. Current smokers had lower levels of FEV1, FVC and FEV1/FVC during the first visit, and a stepper decrement of FEV1 and FEV1/FVC. Ex-smokers who smoked for less than 25 years of stopped smoking more than 14 years ago had similar levels of FEV1 and FVC to never-smokers, but a steeper rate of decline of FEV1/FVC, consistent with ongoing airflow obstruction. No interactions between crocidolite exposure and smoking at the first visit or longitudinally were found. Conclusions Our results show that the deleterious effects of crocidolite exposure on lung function persist in this population, despite asbestos exposure having ceased more than 30 years ago. They also confirm the detrimental effect of smoking on lung function and show the beneficial effects of smoking cessation. Asbestos and tobacco smoking seem to act as independent risk factors for lung function impairment in this population.