Environment and Breast Cancer: Science Review

Evidence From Humans
Print this page
Occupational exposures to engine exhausts and other PAHs and breast cancer risk: A population-based case-control study
Rai, R., Glass, D. C., Heyworth, J. S., Saunders, C., Fritschi, L. Am J Ind Med. 2016. 59:6, 437-44.
Topic area
Environmental pollutant - Air pollution Vehicle exhaust
Study design
Population-based case-control
Funding agency
National Health and Medical Research Council Austr
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
Stratified analysis based on menopausal status.
Number of Controls
Controls: 1,785
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
The Breast Cancer Environment and Employment Study (BCEES) enrolled 1,205 women aged 18-80 years residing in Western Australia (WA) who were diagnosed with first incident invasive breast cancer between May 2009 and July 2011. The study also enrolled 1,789 controls free of breast cancer from among a random selection from the WA Electoral Roll frequency matched to the expected age distribution of cases. Other eligibility criteria included having a correct address, adequate English, and not in poor health or deceased. Cases and controls were excluded from this analysis if they had not completed the occupational history section of the study questionnaire.
Comment about participation selection
These response rates are relatively low and might raise concern about selection bias, especially among the controls. The authors performed sensitivity analyses to consider possible bias. Of note, many studies do not report response rates so it is difficult to determine relative about selection bias in this study compared to others.
Exposure Investigated
Exposures investigated
Lifetime occupational exposure to diesel exhausts, gasoline exhausts, and other exhausts, estimated using OccIDEAS job-specific modules to identify tasks (self-reported) with probable exposure for all jobs held for ≥ 6 months. Frequency, duration, and l
How exposure was measured
Questionnaire, self-administered
Exposure assessment comment
Self-reported occupational exposure made after a breast cancer diagnosis may be subject to recall bias. Authors considered this in analysis.
Early life exposures considered
Yes, exposure before birth of first child
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, country of birth, access to health care services, education, physical activity, alcohol consumption, family history of breast cancer, number of children, age at first child's birth, duration of breastfeeding, HRT use, current BMI and BMI at age 30, S
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
Exposure to engine exhausts, probable exposure vs. none:

Diesel exhaust: aOR 1.07 (95% CI 0.81-1.41)
Gasoline exhaust: aOR 0.98 (95% CI 0.74-1.28)
Other exhaust: aOR 1.08 (95% CI 0.29-4.08)

Premenopausal women
Diesel exhaust: aOR 1.29 (95% CI 0.77-2.18)
Gasoline exhaust: aOR 1.39 (95% CI 0.80-2.43)
Other exhaust (2 cases and 2 controls with probably exposure): aOR 1.07 (95% CI 0.15-7.69)

Postmenopausal women
Diesel exhaust: aOR 0.99 (95% CI 0.72-1.38)
Gasoline exhaust: aOR 0.87 (95% CI 0.63-1.20)
Other exhaust (3 cases and 2 controls with probably exposure): aOR 1.09 (95% CI 0.18-6.50)

Parous women
Diesel exhaust before birth of first child: aOR 1.04 (95% CI 0.68-1.58)
Gasoline exhaust before birth of first child: aOR 1.09 (95% CI 0.57-1.39)
Results Comments
Number of exposed cases/controls not specified for analysis of parous women. Sensitivity analyses of selection bias suggest that (1) if at least 25% of non-responding cases were probably exposed to diesel exhaust (i.e. exposure more prevalent among non-responding cases) or (2) if at most 1% of non-responding controls were probably exposed to diesel exhaust (i.e. exposure less prevalent among non-responding controls), then the unadjusted OR for overall breast cancer would have been strongly positive and statistically significant. For sensitivity analyses of recall bias for diesel exhaust, there was no significant alteration in the unadjusted OR for diesel exhaust and overall breast cancer when it was assumed that 10% of cases over-reported exposure and 20% of controls under-reported exposure.
Author address
School of Public Health, Curtin University Western Australia, Perth, Western Australia. Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria. School of Population Health, The University of Western Australia, Perth, We