title: Is potroom asthma due more to sulphur dioxide than fluoride? An inception cohort study in the Australian aluminium industry.
abstract: OBJECTIVE
  Although an asthma-like syndrome has been recognised in aluminium smelter workers for over 70 years, the causal agent has been difficult to identify.
  
  
  METHODS
  An inception cohort study was conducted at two Australian aluminium smelters where 446 employees participated over a period of 9 years. Cumulative exposures between interviews were estimated from job histories using a task exposure matrix based on measurements in the smelters. Participants completed an MRC respiratory questionnaire, spirometry and methacholine challenge test. Data were analysed with generalised estimating equations to allow for repeated measurements of each participant.
  
  
  RESULTS
  Wheeze and chest tightness, the two symptoms most closely related to asthma, showed associations with occupational exposures. SO(2) exposure was significantly associated with these symptoms, bronchial hyper-responsiveness (BHR) to methacholine (a feature of asthma), airflow limitation (reduced forced expiratory volume in 1 second/forced vital capacity ratio) and longitudinal decline in lung function. Fluoride exposure was associated with the same outcomes, but less strongly. Inhalable dust and the benzene soluble fraction (BSF) were associated with symptoms of asthma and BHR. Although many of the exposures were highly correlated, further modelling suggested that of the known respiratory irritants, SO(2) was more likely than fluoride to be primarily responsible for the symptoms observed. Fluoride, inhalable dust and SO(2) were the most important airborne contaminants associated with effects on lung function.
  
  
  CONCLUSIONS
  The observed effects were detected at contaminant levels within occupational exposure standards, so further reductions are required, particularly in SO(2) exposures.
authors.affiliation: Department of Epidemiology & Preventive Medicine, Monash University, School of Public Health & Preventive Medicine, The Alfred, Melbourne, Victoria 3004, Australia. michael.abramson@monash.edu
authors.forename: Michael John
authors.initials: MJ
authors.lastname: Abramson
authors.forename: Geza Paul
authors.initials: GP
authors.lastname: Benke
authors.forename: Jisheng
authors.initials: J
authors.lastname: Cui
authors.forename: Nicholas Hubert
authors.initials: NH
authors.lastname: de Klerk
authors.forename: Anthony
authors.initials: A
authors.lastname: Del Monaco
authors.forename: Martine
authors.initials: M
authors.lastname: Dennekamp
authors.forename: Lin
authors.initials: L
authors.lastname: Fritschi
authors.forename: Arthur William
authors.initials: AW
authors.lastname: Musk
authors.forename: Malcolm Ross
authors.initials: MR
authors.lastname: Sim
mesh_terms: D000328:Adult; D017677:Age Distribution; D000535:Aluminum; D001249:Asthma / Q000139:chemically induced* / Q000453:epidemiology / Q000503:physiopathology; D001315:Australia / Q000453:epidemiology; D004812:Epidemiologic Methods; D005260:Female; D005459:Fluorides / Q000633:toxicity*; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008297:Male; D008669:Metallurgy; D008875:Middle Aged; D009784:Occupational Diseases / Q000139:chemically induced* / Q000453:epidemiology / Q000503:physiopathology; D016273:Occupational Exposure / Q000009:adverse effects / Q000032:analysis; D017678:Sex Distribution; D013458:Sulfur Dioxide / Q000633:toxicity*; D014797:Vital Capacity / Q000187:drug effects; D055815:Young Adult
chemical_list: D013458:Sulfur Dioxide; D000535:Aluminum; D005459:Fluorides