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.
Key words: Radon, lung cancer, geographic, case-control, Canada
Résumé
OBJECTIF: Le radon est un important facteur de risque du cancer du poumon. Nous utilisons ici des cartes de variation spatiale du radon pour estimer le risque de cancer du poumon associé au fait de vivre dans les régions du Canada fortement exposées au radon.
MÉTHODE: Nous avons estimé la variation spatiale du radon à l’aide de deux méthodes de cartographie. La première a fait appel à une enquête de Santé Canada regroupant 14 000 mesures du radon dans les habitations par région sanitaire, et la deuxième, à des estimations antérieures des régions exposées au radon par la géologie, la géochimie sédimentaire et la spectrométrie gamma aéroportée. Nous avons examiné le risque de cancer du poumon associé au fait de vivre dans ces zones exposées au radon à l’aide d’une étude populationnelle cas-témoins menée entre 1994 et 1997 auprès de 2 390 cas de cancer du poumon et de 3 507 témoins dans huit provinces canadiennes. Nous avons combiné les lieux de résidence des sujets au cours des 20 années précédentes avec les deux méthodes de cartographie pour estimer les expositions écologiques au radon. Des analyses de régression logistique hiérarchiques ont permis d’estimer les rapports de cotes de l’incidence du cancer du poumon, après avoir tenu compte d’un ensemble exhaustif de covariables individuelles et géographiques.
RÉSULTATS: Les régions sanitaires du Canada diffèrent considérablement en ce qui a trait à leurs concentrations moyennes en radon dans les habitations (intervalle: 16–386 Bq/m3) et aux zones géologiques fortement exposées au radon (intervalle: 0–100 %). Dans les modèles multivariés, une hausse de 50 Bq/m3 du radon dans une région sanitaire moyenne était associée à une hausse de 7 % (IC de 95 %: −6–21 %) de la probabilité de cancer du poumon. Pour chaque tranche de 10 ans pendant laquelle les sujets avaient vécu dans des zones géologiques fortement exposées au radon, la probabilité du cancer du poumon augmentait de 11 % (IC de 95 %: 1–23 %).
CONCLUSIONS: Ces constatations sont des preuves supplémentaires que le radon est un important facteur de risque du cancer du poumon, et que les risques sont inégalement répartis au Canada.
Mots clés: radon, tumeurs du poumon, régions géographiques, études cas-témoins, Canada
References
- 1.Darby S. Radon in homes and risk of lung cancer: Collaborative analysis of individual data from 13 European case-control studies. BMJ. 2005;330(7485):223–30. doi: 10.1136/bmj.38308.477650.63. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.IARC. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. 2012. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Krewski D, Lubin JH, Zielinski JM, Alavanja M, Catalan VS, Field RW, et al. A combined analysis of North American case-control studies of residential radon and lung cancer. J Toxicol Environ Health A. 2006;69(7–8):533–97. doi: 10.1080/15287390500260945. [DOI] [PubMed] [Google Scholar]
- 4.Samet JM, Avila-Tang E, Boffetta P, Hannan LM, Olivo-Marston S, Thun MJ, et al. Lung cancer in never smokers: Clinical epidemiology and environmental risk factors. Clin Cancer Res. 2009;15(18):5626–45. doi: 10.1158/1078-0432.CCR-09-0376. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Chen J, Moir D, Whyte J. Radiat Prot Dosimetry. 2012. Canadian population risk of radon induced lung cancer: A re-assessment based on the recent cross-Canada radon survey. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 6.Létourneau EG, Krewski D, Choi NW, Goddard MJ, McGregor RG, Zielinski JM, et al. Case-control study of residential radon and lung cancer in Winnipeg, Manitoba, Canada. Am J Epidemiol. 1994;140(4):310–22. doi: 10.1093/oxfordjournals.aje.a117253. [DOI] [PubMed] [Google Scholar]
- 7.Turner MC, Krewski D, Chen Y, Pope CA, Gapstur S, Thun MJ. Radon and lung cancer in the American Cancer Society cohort. Cancer Epidemiol Biomarkers Prev. 2011;20(3):438–48. doi: 10.1158/1055-9965.EPI-10-1153. [DOI] [PubMed] [Google Scholar]
- 8.Bräuner EV, Andersen CE, Sørensen M, Jovanovic AZ, Gravesen P, Ulbak K, et al. Environ Res. 2012. Residential radon and lung cancer incidence in a Danish cohort. [DOI] [PubMed] [Google Scholar]
- 9.Government of Canada. Cross-Canada Survey of Radon Concentrations in Homes–Final Report. 2012. [Google Scholar]
- 10.Radon Environmental Corp. Radon Potential Map of Canada. 2012. [Google Scholar]
- 11.United States Geological Survey. Geologic radon potential of the United States. 1995. [Google Scholar]
- 12.Johnson KC, Mao Y, Argo J, Dubois S, Semenciw R, Lava J. The National Enhanced Cancer Surveillance System: A case-control approach to environment-related cancer surveillance in Canada. Environmetrics. 1998;9(5):495–504. doi: 10.1002/(SICI)1099-095X(199809/10)9:5<495::AID-ENV318>3.0.CO;2-H. [DOI] [Google Scholar]
- 13.Hystad P, Demers PA, Johnson KC, Brook J, Donkelaar AV, Lamsal L, et al. Spatiotemporal air pollution exposure assessment for a Canadian population-based lung cancer case-control study. Environ Health. 2012;11(1):22. doi: 10.1186/1476-069X-11-22. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14.Hystad P, Carpiano RM, Demers PA, Johnson KC, Brauer M. Neighbourhood socioeconomic status and individual lung cancer risk: Evaluating long-term exposure measures and mediating mechanisms. Soc Sci Med. 2013;97:95–103. doi: 10.1016/j.socscimed.2013.08.005. [DOI] [PubMed] [Google Scholar]
- 15.Health Canada. Radon–Environmental and Workplace Health–Health Canada. 2012. [Google Scholar]
- 16.Statistics Canada. CANSIM–153-0098–Households and the environment survey, knowledge of radon and testing, Canada and provinces. 2010. [Google Scholar]
- 17.Tollefsen T, Gruber V, Bossew P, Cort MD. Status of the European indoor radon map. Radiat Prot Dosimetry. 2011;145(2-3):110–16. doi: 10.1093/rpd/ncr072. [DOI] [PubMed] [Google Scholar]
- 18.Gray A, Read S, McGale P, Darby S. BMJ. 2009. Lung cancer deaths from indoor radon and the cost effectiveness and potential of policies to reduce them. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 19.Bochicchio F. The newest international trend about regulation of indoor radon. Radiat Prot Dosimetry. 2011;146(1–3):2–5. doi: 10.1093/rpd/ncr093. [DOI] [PubMed] [Google Scholar]
- 20.Lantz PM, Mendez D, Philbert MA. Am J Public Health. 2013. Radon, smoking, and lung cancer: The need to refocus radon control policy; pp. e1–e5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 21.Krewski D, Lubin JH, Zielinski JM, Alavanja M, Catalan VS, Field RW, et al. Residential radon and risk of lung cancer: A combined analysis of 7 North American case-control studies. Epidemiology. 2005;16(2):137. doi: 10.1097/01.ede.0000152522.80261.e3. [DOI] [PubMed] [Google Scholar]
- 22.Peterson E, Aker A, Kim J, Li Y, Brand K, Copes R. Cancer Causes Control. 2013. Lung cancer risk from radon in Ontario, Canada: How many lung cancers can we prevent? [DOI] [PMC free article] [PubMed] [Google Scholar]
- 23.Heid IM, Küchenhoff H, Miles J, Kreienbrock L, Wichmann HE. Two dimensions of measurement error: Classical and Berkson error in residential radon exposure assessment. J Expo Sci Environ Epidemiol. 2004;14(5):365–77. doi: 10.1038/sj.jea.7500332. [DOI] [PubMed] [Google Scholar]
- 24.Hauri DD, Huss A, Zimmermann F, Kuehni CE, Röösli M. A prediction model for assessing residential radon concentration in Switzerland. J Environ Radioact. 2012;112:83–89. doi: 10.1016/j.jenvrad.2012.03.014. [DOI] [PubMed] [Google Scholar]
- 25.Rauch SA, Henderson SB. A comparison of two methods for ecologie classification of radon exposure in British Columbia: Residential observations and the Radon Potential Map of Canada. Can J Public Health. 2013;104(3):e240–e245. doi: 10.17269/cjph.104.3794. [DOI] [PMC free article] [PubMed] [Google Scholar]