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Respiratory symptoms and statistical methods
  1. M. Dennekamp1,
  2. G. Benke1,
  3. J. Cui1,
  4. A. Del Monaco1,
  5. A. W. Musk2,
  6. N. de Klerk2,
  7. L. Fritschi3,
  8. M. R. Sim1,
  9. M. J. Abramson4
  1. 1Centre for Occupational and Environmental Health, Monash University
  2. 2School of Population Health, University of Western Australia
  3. 3Western Australian Institute for Medical Research
  4. 4Clinical Epidemiology Unit, Monash University

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    To investigate the incidence of respiratory symptoms and changes in pulmonary function in relation to occupational exposures in two aluminium smelters in Victoria, Australia.


    The study population consisted of employees who started employment between 1995 and the end of 2003 at two aluminium smelter sites in Victoria, Australia. Participation involved an initial assessment at the start of employment and annual follow-up assessments for the duration of employment at the smelters. These assessments involved an interviewer-administered questionnaire which included questions about cough, shortness of breath, wheeze, chest tightness and rhinitis. In addition lung function was assessed by measuring forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC). Methacholine challenge testing was performed to identify bronchial hyper-responsiveness (BHR). The occupational exposures investigated in this study were fluoride, sulphur dioxide (SO2), inspirable dust, benzene soluble fraction (BSF) and oil mist. The exposure levels to these substances were calculated for each participant in the study using their job history information and routine personal air monitoring data. The random effects model was used to investigate the association between occupational exposures and health outcomes.


    In total 446 employees participated in the study. Of the five symptoms, only wheeze and chest tightness, the two symptoms most closely related to asthma, showed associations with exposures at the sites. Workers who were exposed to fluoride, inspirable dust, SO2 and BSF were more likely to report wheeze. Chest tightness was associated with exposure to dust, SO2 and BSF. Many of the exposures were highly correlated, but it is most likely that fluoride and SO2, known respiratory irritants, were responsible for the symptom effects observed. Fluoride, inspirable dust and SO2 were the most important agents having an effect on lung function. A significant reduction in the FEV1/FVC ratio (an …

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