Environment and Breast Cancer: Science Review

Evidence From Humans
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Noticing pesticide spray drift from agricultural pesticide application areas and breast cancer: a case-control study
El-Zaemey, S., Heyworth, J., Fritschi, L. Aust N Z J Public Health. 2013. 37:6, 547-55.
Topic area
Environmental pollutant - Pesticides
Study design
Population based case-control
Funding agency
Australian National Health and Medical Research Co
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
No analysis based on menopausal status
Number of Controls
Controls: 1,743
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Participants were identified through the Breast Cancer Environment and Employment Study. Cases were included from the Western Australia Cancer Registry, who received a first breast cancer diagnosis between 2009-2011, and were between 18-80 years old. Controls were from the Western Australian Electoral Roll (compulsory in Australia), had no history of breast cancer, and were frequency matched to cases based on age.
Comment about participation selection
Participants who lived near an agricultural area for ≥ 1 year and never noticed spray drift served as the study's reference group.
Exposure Investigated
Exposures investigated
Self-reported information about residence near agricultural area, type of agricultural area, noticing spray drift (and if yes, frequency of drifts and first and last age when noticed drifts).
How exposure was measured
Questionnaire, self-administered
Exposure assessment comment
The types or mixtures of pesticides were not known; however, DDT heptachlor, dieldrin, endosulfan, and organophosphate pesticides were registered for use in Western Australia during the recall period in this study. Sensitivity analysis was conducted to account for recall bias: 10% of cases were assumed to over-report, and 20% of controls were assumed to under-report observing pesticide spray drift. Additional assumptions about reporting among non-responding participants were made to account for possible biased sampling. To account for reporting bias, beliefs of pesticides and breast cancer risk were evaluated.
Early life exposures considered
Yes, exposure window before age 20 captures sensitive periods of breast development.
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.
Socio-Economic Indexes for Areas (SEIFA), household and occupational pesticide exposure, access to health services, education, country of birth, family history, age at menarche, age stopped periods, contraceptive use, age at first birth, breast fed at lea
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
Compared to women who never reported noticing spray drift:
Noticed spray drift: OR 1.43 (95% CI 1.15-1.78)
Noticed spray drift from farm: OR 1.39 (95% CI 1.09-1.76)
Noticed spray drift from vineyard: OR 3.16 (95% CI 1.40-7.14)
Noticed spray drift from market garden and nursery: OR 1.52 (95% CI 1.01-2.29)
Noticed spray drift <20 years before diagnosis: OR 1.13 (95% CI 0.70-1.82)
Noticed spray drift ≥20 years before diagnosis: OR 1.51 (95% CI 1.19-2.16)
>20 years old when first noticed spray drift: OR 1.27 (95% CI 0.95-1.72)
≤20 years old when first noticed spray drift: OR 1.61 (95% CI 1.19-2.16)
<10 years old when first noticed spray drift: OR 1.23 (95% CI 0.83-1.85)
≥10 years old when first noticed spray drift: OR 1.51 (95% CI 1.18-1.94)
Noticed spray drift <20 weeks total: OR 1.18 (95% CI 0.79-1.18)
Noticed spray drift 20-65 weeks total: OR 1.32 (95% CI 0.86-1.77)
Noticed spray drift >65 weeks total: OR 1.99 (95% CI 1.42-2.79)
Results Comments
The association between breast cancer risk and noticing spray drift was not significantly different among those who believed that pesticides increases breast cancer risk vs. does not increase breast cancer risk.
Reviewers Comments
Risk remained elevated after adjustment for other sources of pesticide exposure; 88% of both cases and controls reported household pesticide use. Results from household use are reported by the study authors in a different paper.