title: Geographic variation in radon and associated lung cancer risk in Canada.
abstract: OBJECTIVE
  Radon is an important risk factor for lung cancer. Here we use maps of the geographic variation in radon to estimate the lung cancer risk associated with living in high radon areas of Canada.
  
  
  METHODS
  Geographic variation in radon was estimated using two mapping methods. The first used a Health Canada survey of 14,000 residential radon measurements aggregated to health regions, and the second, radon risk areas previously estimated from geology, sediment geochemistry and aerial gamma-ray spectrometry. Lung cancer risk associated with living in these radon areas was examined using a population-based case-control study of 2,390 lung cancer cases and 3,507 controls collected from 1994-1997 in eight Canadian provinces. Residential histories over a 20-year period were used in combination with the two mapping methods to estimate ecological radon exposures. Hierarchical logistic regression analyses were used to estimate odds ratios for lung cancer incidence, after adjusting for a comprehensive set of individual and geographic covariates.
  
  
  RESULTS
  Across health regions in Canada, significant variation in average residential radon concentrations (range: 16-386 Bq/m3) and in high geological-based radon areas (range: 0-100%) is present. In multivariate models, a 50 Bq/m3 increase in average health region radon was associated with a 7% (95% CI: -6-21%) increase in the odds of lung cancer. For every 10 years that individuals lived in high radon geological areas, the odds of lung cancer increased by 11% (95% CI: 1-23%).
  
  
  CONCLUSIONS
  These findings provide further evidence that radon is an important risk factor for lung cancer and that risks are unevenly distributed across Canada.
authors.affiliation: University of British Columbia. phystad@gmail.com.
authors.forename: Perry
authors.initials: P
authors.lastname: Hystad
authors.forename: Michael
authors.initials: M
authors.lastname: Brauer
authors.forename: Paul A
authors.initials: PA
authors.lastname: Demers
authors.forename: Kenneth C
authors.initials: KC
authors.lastname: Johnson
authors.forename: Eleanor
authors.initials: E
authors.lastname: Setton
authors.forename: Alejandro
authors.initials: A
authors.lastname: Cervantes-Larios
authors.forename: Karla
authors.initials: K
authors.lastname: Poplawski
authors.forename: Alana
authors.initials: A
authors.lastname: McFarlane
authors.forename: Alan
authors.initials: A
authors.lastname: Whitehead
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Nicol
mesh_terms: D000368:Aged; D002170:Canada; D016022:Case-Control Studies; D004781:Environmental Exposure / Q000009:adverse effects*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008175:Lung Neoplasms / Q000139:chemically induced*; D008297:Male; D008875:Middle Aged; D011886:Radon / Q000032:analysis* / Q000506:poisoning*; D012111:Residence Characteristics / Q000706:statistics & numerical data*; D012307:Risk Factors
chemical_list: D011886:Radon
keywords: Canada; Radon; case-control; geographic; lung cancer
references.citation: Soc Sci Med. 2013 Nov;97:95-103
references.pmid: 24161094
references.citation: Epidemiology. 2005 Mar;16(2):137-45
references.pmid: 15703527
references.citation: BMJ. 2005 Jan 29;330(7485):223
references.pmid: 15613366
references.citation: BMJ. 2009 Jan 06;338:a3110
references.pmid: 19129153
references.citation: Cancer Causes Control. 2013 Nov;24(11):2013-20
references.pmid: 23982909
references.citation: Radiat Prot Dosimetry. 2011 Jul;146(1-3):2-5
references.pmid: 21561948
references.citation: Environ Health. 2012 Apr 04;11:22
references.pmid: 22475580
references.citation: Cancer Epidemiol Biomarkers Prev. 2011 Mar;20(3):438-48
references.pmid: 21212062
references.citation: J Expo Anal Environ Epidemiol. 2004 Sep;14(5):365-77
references.pmid: 15361895
references.citation: Can J Public Health. 2013 Mar 06;104(3):e240-5
references.pmid: 23823889
references.citation: Environ Res. 2012 Oct;118:130-6
references.pmid: 22749110
references.citation: Radiat Prot Dosimetry. 2011 May;145(2-3):110-6
references.pmid: 21460365
references.citation: Environ Health Perspect. 1994 Jun;102(6-7):590-1
references.pmid: 9679121
references.citation: J Toxicol Environ Health A. 2006 Apr;69(7):533-97
references.pmid: 16608828
references.citation: Am J Public Health. 2013 Mar;103(3):443-7
references.pmid: 23327258
references.citation: Radiat Prot Dosimetry. 2012 Nov;152(1-3):9-13
references.pmid: 22874897
references.citation: Am J Epidemiol. 1994 Aug 15;140(4):310-22
references.pmid: 8059766
references.citation: J Environ Radioact. 2012 Oct;112:83-9
references.pmid: 22683900
references.citation: Clin Cancer Res. 2009 Sep 15;15(18):5626-45
references.pmid: 19755391