Exposure to ambient air pollution and the incidence of lung cancer and breast cancer in the Ontario Population Health and Environment Cohort
- DOI
- Language of the publication
- English
- Date
- 2019-07-15
- Type
- Article
- Author(s)
- Bai, Li
- Shin, Saeha
- Burnett, Richard T.
- Kwong, Jeffrey C.
- Hystad, Perry
- van Donkelaar, Aaron
- Goldberg, Mark S.
- Lavigne, Eric
- Weichenthal, Scott
- Martin, Randall V.
- Copes, Ray
- Kopp, Alexander
- Chen, Hong
- Publisher
- Wiley
Abstract
Lung and female breast cancers are highly prevalent worldwide. Although the association between exposure to ambient fine particulate matter (PM2.5) and lung cancer has been recognized, there is less evidence for associations with other common air pollutants such as nitrogen dioxide (NO2) and ozone (O3). Even less is known about potential associations between these pollutants and breast cancer. We conducted a population-based cohort study to investigate the associations of chronic exposure to PM2.5, NO2, O3 and redox-weighted average of NO2 and O3 (Ox) with incident lung and breast cancer, using the Ontario Population Health and Environment Cohort (ONPHEC), which includes all long-term residents aged 35–85 years who lived in Ontario, Canada, 2001–2015. Incident lung and breast cancers were ascertained using the Ontario Cancer Registry. Annual estimates of exposures were assigned to the residential postal codes of subjects for each year during follow-up. We used Cox proportional-hazards models adjusting for personal- and neighborhood-level covariates. Our cohorts for lung and breast cancer analyses included ~4.9 million individuals and ~2.5 million women, respectively. During follow-up, 100,146 incident cases of lung cancer and 91,146 incident cases of breast cancer were diagnosed. The fully adjusted analyses showed positive associations of lung cancer incidence with PM2.5 (hazard ratio [HR] = 1.02 [95% CI: 1.01–1.05] per 5.3 μg/m3) and NO2 (HR = 1.05 [95% CI: 1.03–1.07] per 14 ppb). No associations with lung cancer were observed for O3 or Ox. Relationships between PM2.5 and NO2 with lung cancer exhibited a sublinear shape. We did not find compelling evidence linking air pollution to breast cancer.
Plain language summary
"Under the Federal Clean Air Regulatory Agenda (CARA), Health Canada conducts scientific research to evaluate the health risks of ambient air pollution. Exposures to common air pollutants such as fine particulate matter (PM2.5) are known to increase cancer-related mortality and morbidity. Although the association between ambient PM2.5 and the incidence of lung cancer has been well established, evidence is inconclusive for the associations of lung cancer with other common air pollutants such as nitrogen dioxide (NO2) and ozone (O3). Even less evidence exists about the associations of long-term exposure to these pollutants with the incidence of breast cancer, a leading cancer among women worldwide. Health Canada led a large cohort study in collaboration with researchers from other organizations to investigate the associations between air pollution and incidence of lung cancer and breast cancer and also to describe the shape of pollutant-disease relationships. In this study, a population-based cohort comprising about 4.9 million long-term Ontario residents was followed in 2001-2015. The occurrence of lung cancer and breast cancer were established from data linkage to population-based cancer registry in the province. Increased risk for lung cancer was found in association with PM2.5 and NO2, with a 2-5% higher risk of developing lung cancer after adjusting for various covariates. No associations with O3 or a novel measure of oxidative capacity of gaseous pollutants (Ox) were found for lung cancer. Additionally, the associations for lung cancer with PM2.5 and NO2 exhibited a sublinear shape (ie, more drastic increase in the risk of lung cancer at the higher levels of air pollution). In contrast, there was no strong evidence linking these pollutants to breast cancer incidence. These results suggest that ambient air pollution is linked to the onset of lung cancer, even at the relatively low concentrations typically seen in Ontario. This study also highlights the importance of considering outcome- and pollutant-specific shapes when conducing health impact assessments of air pollution."
Subject
- Health,
- Health and safety