Environment and Breast Cancer: Science Review

Evidence From Humans
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Mortality in small geographical areas and proximity to air polluting industries in the Basque Country (Spain)
Cambra, K., Martinez-Rueda, T., Alonso-Fustel, E., Cirarda, F. B., Ibanez, B., Esnaola, S., Calvo, M., Aldasoro, E., Montoya, I. Occup Environ Med. 2011. 68:2, 140-7.
Topic area
Environmental pollutant - Air pollution
Study design
Retrospective cohort
Funding agency
Fondo de Investigaciones Sanitarias
Study Participants
Number of Cases
Not reported
Menopausal Status
The menopausal status of women included in this study is listed here.
No analyses by menopausal status
Number in Cohort
Cohort: 1,645 census sections, with a mean size of 1,257 inhabitants
Cohort participation rate
Not applicable. This study was records-based.
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
The study population consisted of all residents in the 2001 Basque County census. Census sections with more than 500 inhabitants were the unit for analysis (average 1,257 inhabitants). Smaller census sections were integrated into adjacent sections.
Comment about participation selection
No individual data, such as the length of residency or breast cancer risk factors were included.
Exposure Investigated
Exposures investigated
Proximity of residence listed in 2001 Housing Census to industries operating in 2001 that had declared pollutant emissions to the European Pollutant Emission Register (EPER).
How exposure was measured
Geographic location
Exposure assessment comment
Exposure was measured by proximity to industrial sites that declared pollutant emissions to the European Pollutant Emission Register. The two proximity measures were either the center of census sections 1,000 meters from a polluting site, or 2,000 meters from a polluting site. Although the Besag, York, and Mollie (BYM) models include a spatial component, as well as proximity to a polluting industry, the proximity measurements do not include air dispersion modeling, which may affect the distribution of pollutants in the census sections.
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.
Mortality cause, distance from polluting industry, type of industrial activity, and socioeconomic status.
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
Census section centroid < 1 km from:
Energy industry: RR 0.97 (95% CI 0.70-1.31)
Metal processing industry: RR 1.12 (95% CI 0.98-1.27)
Mineral industry: RR 0.97 (95% CI 0.78-1.21)
Chemical industry: RR 0.83 (95% CI 0.65-1.03)
Waste industry: RR 0.83 (95% CI 0.42-1.42)
Results Comments
The authors state that excess mortality from breast cancer in the 2,000 meter buffer needs a further investigation to discriminate if the excess is in cancer incidence or mortality. Authors note that per the EPER data, among industries in the study area, metal processing industries were the main source of heavy metal, polycyclic aromatic hydrocarbons (PAHs) and benzene emissions, as well as a major source of particulate matter emissions.
Author address
Directorate of Public Health, Department of Health, Basque Government, C/ Donostia-San Sebastian 1, 01010, Vitoria-Gasteiz, Spain. kcambra@telefonica.net
Reviewers Comments
This is an exploratory study that does not include residential history, work history and exposures, and well-known risk factors for breast cancer. The latency of disease is not captured by a cross-sectional study, and because many women survive breast cancer, mortality is an insensitive outcome.