title: Residential radon and risk of lung cancer: a combined analysis of 7 North American case-control studies.
abstract: BACKGROUND
  Underground miners exposed to high levels of radon have an excess risk of lung cancer. Residential exposure to radon is at much lower levels, and the risk of lung cancer with residential exposure is less clear. We conducted a systematic analysis of pooled data from all North American residential radon studies.
  
  
  METHODS
  The pooling project included original data from 7 North American case-control studies, all of which used long-term alpha-track detectors to assess residential radon concentrations. A total of 3662 cases and 4966 controls were retained for the analysis. We used conditional likelihood regression to estimate the excess risk of lung cancer.
  
  
  RESULTS
  Odds ratios (ORs) for lung cancer increased with residential radon concentration. The estimated OR after exposure to radon at a concentration of 100 Bq/m3 in the exposure time window 5 to 30 years before the index date was 1.11 (95% confidence interval = 1.00-1.28). This estimate is compatible with the estimate of 1.12 (1.02-1.25) predicted by downward extrapolation of the miner data. There was no evidence of heterogeneity of radon effects across studies. There was no apparent heterogeneity in the association by sex, educational level, type of respondent (proxy or self), or cigarette smoking, although there was some evidence of a decreasing radon-associated lung cancer risk with age. Analyses restricted to subsets of the data with presumed more accurate radon dosimetry resulted in increased estimates of risk.
  
  
  CONCLUSIONS
  These results provide direct evidence of an association between residential radon and lung cancer risk, a finding predicted using miner data and consistent with results from animal and in vitro studies.
authors.affiliation: McLaughlin Centre for Population Health Risk Assessment, University of Ottawa, Ottawa, Ontario, Canada. dkrewski@uottawa.ca
authors.forename: Daniel
authors.initials: D
authors.lastname: Krewski
authors.forename: Jay H
authors.initials: JH
authors.lastname: Lubin
authors.forename: Jan M
authors.initials: JM
authors.lastname: Zielinski
authors.forename: Michael
authors.initials: M
authors.lastname: Alavanja
authors.forename: Vanessa S
authors.initials: VS
authors.lastname: Catalan
authors.forename: R William
authors.initials: RW
authors.lastname: Field
authors.forename: Judith B
authors.initials: JB
authors.lastname: Klotz
authors.forename: Ernest G
authors.initials: EG
authors.lastname: Létourneau
authors.forename: Charles F
authors.initials: CF
authors.lastname: Lynch
authors.forename: Joseph I
authors.initials: JI
authors.lastname: Lyon
authors.forename: Dale P
authors.initials: DP
authors.lastname: Sandler
authors.forename: Janet B
authors.initials: JB
authors.lastname: Schoenberg
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Steck
authors.forename: Jan A
authors.initials: JA
authors.lastname: Stolwijk
authors.forename: Clarice
authors.initials: C
authors.lastname: Weinberg
authors.forename: Homer B
authors.initials: HB
authors.lastname: Wilcox
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D004781:Environmental Exposure; D005260:Female; D006798:Housing; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D009656:North America / Q000453:epidemiology; D016017:Odds Ratio; D011886:Radon / Q000506:poisoning*; D018570:Risk Assessment
chemical_list: D011886:Radon