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UBC Theses and Dissertations

A spatial assessment of environmental risk factors for lung cancer in Canada : the role of air pollution, radon and neighborhood socioeconomic status Hystad, Perry Wesley


In this dissertation I examined whether three exposures associated with the physical and social residential environment − specifically, ambient air pollution, radon and neighborhood socioeconomic status (SES) − are risk factors for the development of lung cancer in Canada. Throughout this dissertation I used the National Enhanced Cancer Surveillance System (NECSS), a large population-based case-control study conducted in eight Canadian provinces, including 3,280 incident lung cancer cases and 5,073 population controls. In the first section of this dissertation, I developed methods to estimate ambient air pollution, both nationally and retrospectively, and applied these to 20 years of residential histories in the NECSS study. Epidemiological analyses showed that the odds of lung cancer incidence associated with a 10-unit increase in PM₂.₅ (µg/m³), NO₂ (ppb) and O₃ (ppb) were 1.29 (95% CI = 0.95-1.76), 1.11 (1.00-1.24), and 1.09 (0.85-1.39) respectively, indicating that ambient air pollution exposure is associated with lung cancer development in Canada. In the second section, I used maps of radon concentration and potential in combination with the NECSS residential histories to estimate ecological radon exposures. A 50 Bq/m³ increase in average health region radon concentration was associated with a 7% (-6-21%) increase in the odds of lung cancer and for every 10 years that individuals lived in high radon potential zones, the odds of lung cancer increased by 11% (1-23%). This study also indicated that risk mapping may be used to target population health prevention efforts for radon. In the third section, I developed methods to estimate long-term exposure to neighborhood SES and applied these to the residential histories of the NECSS study. The odds of lung cancer cases residing in the most versus least deprived long-term neighborhood SES quintiles were significantly elevated and in the city sub-analysis remained significant (OR: 1.38 (1.01-1.88)) after adjusting for smoking and other lung cancer risk factors. Smoking behavior was the predominant partial-mediating pathway of the neighborhood effect. Collectively, this dissertation contributes to the methodological literature on spatial exposure assessment and spatial epidemiology, as well as to the etiological evidence linking air pollution, radon and neighborhood SES to lung cancer risk.

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