Abstract:
Background: Predictors of incident respiratory symptoms described in aluminum smelter workers remain unclear.
Method: We analyzed data from a longitudinal study of naïve aluminum smelter workers. The Venables asthma-like symptom instrument and the ATS respiratory symptom instrument were administered to workers at hire and then several times after work exposure had started. The presence of two or more Venable symptoms (cough, wheeze or breathlessness) defined the asthma-like complex.
Results: 87 subjects had valid one-year follow-up assessment: 11 (12.2%) of these workers developed new asthma-like symptom complex. 113 subjects had at least one valid follow-up between 6 months and 2 years after hire: of these 19 (16.9%) had developed asthma-like symptom complex by their last follow-up interview (mean duration of follow-up = 1.6 yrs). Subjects with FEV1/FVC < 0.75 at hire had a 3.7 fold risk (95% CI: 1.7, 8.1) of developing new asthma-like complex by their last follow-up compared to those with higher FEV1 ratio. Smokers at hire were 2.1 (CI 0.9, 4.7) times more likely to develop asthma-like symptom complex compared to never or ex-smokers. Atopy (measured by skin prick testing) at hire and parental asthma or allergy were not associated with development of the symptom complex. One year after hire13.0% (12) of workers had developed new phlegm and 10.6% (10) had developed cough (ATS instrument). Smokers at hire had an increased risk for developing incident phlegm production (5.9 [1.4, 29.1].
Conclusions: Naïve aluminum smelter workers developed asthma like symptoms within one year of exposure to the potroom. Reduced FEV1/FVC ratio at hire was associated with increased likelihood for symptom development.