title: Occupational exposure to asbestos and lung cancer in men: evidence from a population-based case-control study in eight Canadian provinces.
abstract: BACKGROUND
  Asbestos is classified as a human carcinogen, and studies have consistently demonstrated that workplace exposure to it increases the risk of developing lung cancer. Few studies have evaluated risks in population-based settings where there is a greater variety in the types of occupations, and exposures.
  
  
  METHODS
  This was a population based case-control study with 1,681 incident cases of lung cancer, and 2,053 controls recruited from 8 Canadian provinces between 1994 and 1997. Self-reported questionnaires were used to elicit a lifetime occupational history, including general tasks, and information for other risk factors. Occupational hygienists, who were blinded to case-control status, assigned asbestos exposures to each job on the basis of (i) concentration (low, medium, high), (ii) frequency (<5%, 5-30%, and >30% of the time in a normal work week), and (iii) reliability (possible, probable, definite). Logistic regression was used to estimate odds ratios (ORs) and their corresponding 95% confidence intervals (CI).
  
  
  RESULTS
  Those occupationally exposed to (i) low, and (ii) medium or high concentrations of asbestos had ORs for lung cancer of 1.17 (95% CI=0.92 - 1.50) and 2.16 (95% CI=1.21-3.88), respectively, relative to those who were unexposed. Medium or high exposure to asbestos roughly doubled the risk for lung cancer across all three smoking pack-year categories. The joint relationship between smoking and asbestos was consistent with a multiplicative risk model.
  
  
  CONCLUSIONS
  Our findings provide further evidence that exposure to asbestos has contributed to an increased risk of lung cancer in Canadian workplaces, and suggests that nearly 3% of lung cancers among Canadian men are caused by occupational exposure to asbestos.
authors.affiliation: Population Studies Division, Health Canada, Ottawa, Ontario, Canada. Paul.Villeneuve@hc-sc.gc.ca
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Villeneuve
authors.forename: Marie-Élise
authors.initials: MÉ
authors.lastname: Parent
authors.forename: Shelley A
authors.initials: SA
authors.lastname: Harris
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Johnson
mesh_terms: D001194:Asbestos / Q000009:adverse effects*; D002170:Canada / Q000453:epidemiology; D016022:Case-Control Studies; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D009784:Occupational Diseases / Q000453:epidemiology / Q000209:etiology*; D016273:Occupational Exposure / Q000009:adverse effects*; D016017:Odds Ratio; D011795:Surveys and Questionnaires
chemical_list: D001194:Asbestos