Environment and Breast Cancer: Science Review

Evidence From Humans
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Air pollution from traffic and cancer incidence: a Danish cohort study
Raaschou-Nielsen, O., Andersen, Z. J., Hvidberg, M., Jensen, S. S., Ketzel, M., Sorensen, M., Hansen, J., Loft, S., Overvad, K., Tjonneland, A. Environ Health. 2011. 10, 67.
Topic area
Environmental pollutant - Air pollution
Study design
Prospective cohort
Funding agency
Danish Agency for Science, Technology and Innovati
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
No analyses based on menopausal status
Number in Cohort
Cohort: 27,735 women
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
The Danish, Diet and Health cohort enrolled 57,053 individuals between 1993-1997, including 28,435 women aged 50-64 years living in Copenhagen and Aarhus areas, and followed them until 2006 in the Danish Cancer Registry and Danish Pathology Data Bank. Participants were excluded from this analysis if they had a cancer diagnosis before enrollment, had an uncertain date of diagnosis, address could not be geocoded, address history was not available in central registry for at least 80% of time until diagnosis or censoring at date of death, loss to follow-up, or diagnosis with a cancer other than the one under study.
Exposure Investigated
Exposures investigated
Up to 35-year (1971-2006) geocoded residential history obtained from Central Population Registry and linked to time-weighted average NOX levels estimated with Danish AirGIS modeling system. AirGIS includes data from 1960-2005 on local air pollution from s
Exposure assessment comment
NOx is considered a marker for traffic-related pollution. This exposure assessment accounted for changes in NOX levels over time and changes in participants' addresses.
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.
BMI, education, alcohol, number of childbirths, age at first childbirth, lactation, HRT use, benign breast disease, physical activity, and occupation
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
Average NOx (per 100 μg/m3 increase) 1971-2006 or diagnosis/censoring: aIRR 1.16 (95% CI 0.89-1.51)

Residential markers of traffic exposure at time of enrollment (1993-1997):
Residence within 50m of major street (vs. no): aIRR 0.98 (95% CI 0.78-1.22)
Per 104 vehicle km/day within 200m of residence: aIRR 0.98 (95% CI 0.88-1.10)
Results Comments
Most women in this study were postmenopausal
Author address
Institute of Cancer Epidemiology, Danish Cancer Society, Copenhagen, Denmark. ole@cancer.dk