HOSSEIN SIAHPUSH
Longitudinal Study of Asthma-like Symptoms in Aluminum Smelters Work
Industrial Hygiene and Safety, MS
Preceptor: Joel Kaufman, MD, MPH
The predictors of "potroom asthma", commonly described among aluminum workers, are not clear. It is not adequately known if the risk of developing asthma in new workers is associated with preemployment characteristics. This analysis uses the data from a 2-year follow-up in WA State potroom workers. All of the workers underwent respiratory tests including methacholine challenge and an interview at hire. This affords a unique opportunity for study of preemployment health characteristics. The study included the questions from Venables' asthma questionnaire and the American Thoracic Society (ATS) questionnaire. Potential predictors measured at baseline are: smoking status, ratio of FEV1 to FVC, asthma history in parents, atopy by skin prick test, age, history of childhood asthma, and airway responsiveness as measured by the methacholine challenge test.
The average duration of follow-up was 584 days for the following analysis, which included a cohort of 118 subjects. Asthma-like symptoms include wheeze, cough, and breathlessness. Using the first and last asthma questionnaires, FEV1/FVC at baseline was the strongest predictor of development of asthma-like symptoms (RR: 3.88, 95% CI: 1.8 to 8.41). The risk of developing symptoms was 2.17 times higher among smokers than others (CI: 0.99 to 4.75). Other variables including atopy at the baseline were not associated with the asthma-like symptoms.
Using the one-year follow-up analysis, only smoking at the baseline was associated with development of asthma-like symptoms in 98 subjects (RR: 3.7, 95% CI: 1.13 to 12.11). The incidence in the following symptoms was reported with the highest frequency (11 to 21%): symptoms in eyes and nose, bringing up phlegm and coughing. Baseline smoking had a high relative risk (RR) for a change in the following symptoms: bringing up phlegm (4.93, 95% CI: 1.61 to 15.16), sore or dry throat (2.83, 95% CI: 1.22 to 6.57) and coughing (2.69, 95% CI: 0.98 to 8.97). Subjects with a history of childhood asthma had 3.67 times higher risk of developing coughing (95% CI: 1.01 to 13.34). The baseline methacholine challenge test result was related to developing eye symptoms (RR: 2.66, 95% CI: 1.24 to 5.69).
These results indicate that symptom development including asthma-like symptoms is common among the aluminum smelter workers. Smoking and obstructive pattern of lung function appear to be associated with symptom development.
