BRONCHIAL RESPONSIVENESS AND DECLINE IN FEV1 IN ALUMINUM POTROOM WORKERS

We have investigated the relationship between annual decline in forced expiratory volume in one second (Delta FEV(1)) and bronchial responsi veness (BR) in aluminium potroom workers. BR was measured in a cross-s ectional study of 337 aluminium potroom workers half-way through a 6 y r follow-up study of lung function. A skin-prick test (SPT) was also p erformed. During follow-up the mean number of measurements of lung fun ction (FEV(1)) in each subject was 6.8. Mean Delta FEV(1) was 21.3 ml. yr(-1) (within subject sD=30.5 ml.yr(-1). Mean Delta FEV(1) was 57.0, 44.5 and 16.6 ml.yr(-1) in subjects who had provocative concentration producing a 20% fall in FEV(1) (PC20) less than or equal to 8.0, 8.1-3 2.0 and >32.0 mg.ml(-1), respectively. After adjustment for gender, at opy, smoking habit, FEV(1), age and familial asthma the association be tween BR and Delta FEV(1) was weakened, and was not statistically sign ificant, A significantly accelerated decline in FEV(1) with age was fo und. The difference in Delta FEV(1) between smokers and nonsmokers was 39.3 ml.yr(-1), and between subjects who had a positive skin-prick te st compared to subjects with a negative skin-prick test 39.6 ml.yr(-1) . In subjects reporting work-related asthmatic symptoms the decline in FEV(1) was 43.2 ml.yr(-1) greater than in asymptomatic subjects. In a symptomatic subjects, positive skin-prick test was also associated wit h increased Delta FEV(1). These data indicate that a single measuremen t of BR is not a predictor of Delta FEV(1) in aluminium potroom worker s. Smoking, work-related asthmatic symptoms, and positive reaction to skin-prick test in asymptomatic workers were risk factors of increased Delta FEV(1).