Environment and Breast Cancer: Science Review

Evidence From Humans
Print this page
Exposure to traffic-related air pollution and the risk of developing breast cancer among women in eight Canadian provinces: A case-control study
Hystad, P., Villeneuve, P. J., Goldberg, M. S., Crouse, D. L., Johnson, K. Environ Int. 2015. 74, 240-8.
Topic area
Environmental pollutant - Air pollution NO2
Study design
Population based case-control
Funding agency
Canadian Institute for Health Research Frederick B
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Analyses stratified by menopausal status
Number of Controls
Controls: 1,624
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Cases and controls were identified from a collaborative population-based case-control study, the National Enhanced Cancer Surveillance System with at least 18 years of residential history information in 8 Canadian provinces between 1975-1994.Controls were matched on age and gender.
Comment about participation selection
Premenopausal cases were over-sampled to explore relationships between exposure to air pollution and breast cancer in younger women.
Exposure Investigated
Exposures investigated
Geocoded postal codes from self-reported residential history used to estimate mean residential NO2 exposure (considered marker of traffic-related air pollution) over the period 1975-1994 with: (1) Ground-level NO2 estimates from 2005-2011 satellite NO2 le
How exposure was measured
Environmental sample GIS/Geographic location
Exposure assessment comment
Study accounted for participants moving addresses during the study period.
Breast cancer outcome investigated
Primary incident breast cancer
Confounders considered
Other breast cancer risk factors, such as family history, age at first birth, and hormone replacement therapy use, that were taken into account in the study.
Age, study province, age at menarche, years of menstruation, parity, age at first full-term pregnancy, ever breast fed, bilateral oophorectomy, BMI, smoking pack-years, years since smoking cessation, alcohol consumption, median household income, and years
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
Strength of associations reported
Among all women:
Scaled satellite NO2, per 10 ppb: aOR 1.13 (95% CI 0.99-1.27)
National LUR model, per 10 ppb: aOR 1.08 (95% CI 0.90-1.28)

Among premenopausal women:
Scaled satellite NO2, per 10 ppb: aOR 1.32 (95% CI 1.05-1.67)
National LUR model, per 10 ppb: aOR 1.28 (95% CI 0.92-1.79)

Among postmenopausal women:
Scaled satellite NO2, per 10 ppb: aOR 1.10 (95% CI 0.94-1.28)
National LUR model, per 10 ppb: aOR 1.07 (95% CI 0.86-1.32)
Results Comments
Number of years living near roadways was not significantly associated with breast cancer. Premenopausal ORs were attenuated in models using residence at study entry, compared to all 18 years of residential history.
Author address
College of Public Health and Human Sciences, Oregon State University, Corvallis, OR, USA. Electronic address: perry.hystad@oregonstate.edu. Department of Health Sciences, Carleton University, Ottawa, Ontario, Canada. Department of Medicine, McGill Univers