Environment and Breast Cancer: Science Review

Evidence From Humans
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Household and occupational exposure to pesticides and risk of breast cancer
El-Zaemey, S., Heyworth, J., Glass, D. C., Peters, S., Fritschi, L. Int J Environ Health Res. 2014. .
Topic area
Environmental pollutant - Pesticides
Study design
Population based case-control
Funding agency
Not reported
Study Participants
Menopausal Status
The menopausal status of women included in this study is listed here.
No analyses based on menopausal status
Number of Controls
Controls: 1,789
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, were between 18-80 years old, and lived in Western Australia. Controls were from the Western Australian Electoral Roll, had no history of breast cancer, and were frequency matched to cases for age.
Comment about participation selection
Women who did not report occupational exposures (for occupational analysis); women who did not report household exposures for household analysis served as the study's reference group, which likely included unemployed women and women with white collar jobs, which could result in underestimation of the association.
Exposure Investigated
Exposures investigated
Self-reported household pesticide use (home gardening, insects inside the house, fleas or ticks for pets, ants or termites in the home, ants or termites in the garden) during adulthood and lifetime occupational (OccIDEAS interview) pesticide use (job hist
How exposure was measured
Questionnaire, self-administered Questionnaire, telephone
Exposure assessment comment
To account for reporting bias, beliefs of pesticides and breast cancer risk were evaluated.
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
Ever vs never mixed or applied pesticides: OR 0.77 (95% CI 0.45-1.32)

Household (ever vs never in adulthood):
Any pesticide OR 1.10 (95% CI 0.86-1.37)
Gardening/landscaping OR 1.05 (95% CI 0.83-1.33)
Spraying insects in home OR 1.10 (95% CI 0.87-1.39)
Results Comments
No statistically significant associations were observed for home pesticide use for other pest categories (flea/ticks on pets, termites in home, termites in garden), frequency of exposure (low, medium, high), or ever/never use. A similar proportion of cases and controls believed pesticides may cause breast cancer, and household pesticide use analyses stratified by belief were not associated with statistically significant differences in risk.
Author address
a The University of Western , School of Population Health , 35 Stirling Highway , Crawley , 6009 , Australia.
Reviewers Comments
Because 90% of the participants reported household pesticide use, lack of variation in exposure may prevent the ability to see risks associated with some pesticide use. The authors state that the occupational risks may be imprecise because there was a small number of exposed women in the study. The timing of exposure to household pesticides was not captured in this study, which limits the ability to evaluate risks from exposure during sensitive windows of mammary gland development.