title: Incidence of chronic bronchitis in a cohort of pulp mill workers with repeated gassings to sulphur dioxide and other irritant gases.
abstract: BACKGROUND
  Occupational exposure to irritants is associated with chronic bronchitis. The aim of this study was to elucidate whether repeated peak exposures with respiratory symptoms, gassings, to sulphur dioxide (SO2) and other irritant gases could increase the risk of chronic bronchitis.
  
  
  METHODS
  The study population comprised 3,060 Swedish pulp mill workers (84% males) from a cohort study, who completed a comprehensive questionnaire with items on chronic bronchitis symptoms, smoking habit, occupational history, and specific exposures, including gassings. 2,037 have worked in sulphite mills. Incidence rates and hazard ratios (HRs) for the observation period, 1970-2000, in relation to exposure and the frequency of repeated gassings to SO2 and other irritant gases were calculated.
  
  
  RESULTS
  The incidence rate for chronic bronchitis among workers with repeated gassings was 3.5/1,000 person-years compared with 1.5/1,000 person-years among unexposed workers (HR 2.1, 95% confidence interval (CI) 1.4-3.1). The risk was even higher in the subgroup with frequent gassings (HR 3.2, 95% CI 2.0-5.2), particularly among never-smokers (HR 8.7, 95% CI 3.5-22).
  
  
  CONCLUSIONS
  Repeated gassings to irritant gases increased the incidence of chronic bronchitis in our study population during and after work in pulp mills, supporting the hypothesis that occupational exposures to irritants negatively affect the airways. These results underscore the importance of preventive actions in this work environment.
authors.affiliation: Department of Occupational and Environmental Medicine, Sahlgrenska University Hospital, Göteborg, Sweden. eva.andersson@amm.gu.se.
authors.forename: Eva
authors.initials: E
authors.lastname: Andersson
authors.forename: Nicola
authors.initials: N
authors.lastname: Murgia
authors.forename: Tohr
authors.initials: T
authors.lastname: Nilsson
authors.forename: Berndt
authors.initials: B
authors.lastname: Karlsson
authors.forename: Kjell
authors.initials: K
authors.lastname: Torén
mesh_terms: D000328:Adult; D000395:Air Pollutants, Occupational / Q000633:toxicity*; D029481:Bronchitis, Chronic / Q000139:chemically induced / Q000453:epidemiology*; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D005740:Gases / Q000633:toxicity; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009784:Occupational Diseases / Q000139:chemically induced / Q000453:epidemiology*; D016273:Occupational Exposure; D013458:Sulfur Dioxide / Q000633:toxicity*; D013548:Sweden / Q000453:epidemiology
chemical_list: D000395:Air Pollutants, Occupational; D005740:Gases; D013458:Sulfur Dioxide