Evidence From Humans
 
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Using residential history and groundwater modeling to examine drinking water exposure and breast cancer
Gallagher, L. G., Webster, T. F., Aschengrau, A., Vieira, V. M. Environ Health Perspect. 2010. 118:6, 749-55.
Topic area
Environmental pollutant - Drinking Water Wastewater
Study design
Population based case-control
Funding agency
NCI NIEHS
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: 842
Participant selection: Inclusion and exclusion criteria
Criteria used to select participants in the study.
Study participants were drawn from among permanent residents of 5 towns on Cape Cod. Cases were women diagnosed with breast cancer between 1983 and 1993, identified using the Massachusetts Cancer Registry. Frequency-matched controls (by date of birth and vital status) were chosen by random digit dialing (<65 years) or selected from CMS databases (>=65 years). Deceased controls were selected randomly from death certificates, frequency matched by age and year of death. Proxy respondents (next of kin) for cases or controls who were deceased or unable to participate in the interview were used.
Exposure Investigated
Exposures investigated
Exposure to wastewater effluent from Barnstable Water Pollution Control Facility (BWPCF) in drinking water at self-reported residential address 1947-1993, based on groundwater modeling and historical data on the public water supply. Exposure modeled for b
How exposure was measured
GIS/geographic location Environmental sample
Exposure assessment comment
Because of limited available historical data, specific contaminants in drinking water were not identified. Additional exposures not related to the waste water treatment facility implicated in this study were very possible. Furthermore, exposures experienced off Cape Cod and drinking water activity patterns related to exposure are not assessed. Never-exposed women whose drinking water (public or private supply) was not affected by BWPCF effluent served as the study's reference group.
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 at diagnosis, vital status at interview, family history, personal history of breast cancer, age at first live birth or stillbirth, education, race, study population
Genetic characterization included
If the study analyzed relationships between environmental factors and inherited genetic variations, this field will be marked “Yes.” “No”, if not.
No
Strength of associations reported
High pumping rate scenario:
Ever vs. never exposed, 0-year latency: OR 1.1 (95% CI 0.9-1.5)
>0-5 years exposure, 0-year latency: OR 0.9 (95% CI 0.5-1.5)
>5 years exposure, 0-year latency: OR 1.3 (95% CI 0.9-1.8)
>10 years exposure, 0-latency: OR 1.3 (95% CI 0.9-1.9)

Ever vs. never exposed, 10-year latency: OR 1.3 (95% CI 0.9-1.8)
>0-5 years exposure, 10-year latency: OR 1.1 (95% CI 0.6-1.8)
>5 years exposure, 10-year latency: OR 1.4 (95% CI 0.9-2.2)
>10 years exposure, 10-latency: OR 1.6 (95% CI 0.8-3.2)
Results Comments
Highest ORs were observed in sub-analysis stratifying by bottled water use. ORs = 2.5 (1.2-5.3) and 1.0 (0.3-3.3) for non-bottled users and bottled water users, for ever vs never use, allowing a 20 year latency. Results were not substantially different for >10 years of exposure, for 10 year latency period, or in sensitivity analysis assuming lower pumping rate.
Abstract
Background: Spatial analyses of case-control data have suggested a possible link between breast cancer and groundwater plumes in upper Cape Cod, Massachusetts.Objective: We integrated residential histories, public water distribution systems, and groundwater modeling within geographic information systems (GIS) to examine the association between exposure to drinking water that has been contaminated by wastewater effluent and breast cancer.Methods: Exposure was assessed from 1947 to 1993 for 638 breast cancer cases who were diagnosed from 1983 to 1993 and 842 controls; we took into account residential mobility and drinking water source. To estimate the historical impact of effluent on drinking water wells, we modified a modular three-dimensional finite-difference groundwater model (MODFLOW) from the U.S. Geological Survey. The analyses included latency and exposure duration.Results: Wastewater effluent impacted the drinking water wells of study participants as early as 1966. For > 0-5 years of exposure (versus no exposure), associations were generally null. Adjusted odds ratios (AORs) for > 10 years of exposure were slightly increased, assuming latency periods of 0 or 10 years [AOR = 1.3; 95% confidence interval (CI), 0.9-1.9 and AOR = 1.6; 95% CI, 0.8-3.2, respectively]. Statistically significant associations were estimated for ever-exposed versus never-exposed women when a 20-year latency period was assumed (AOR = 1.9; 95% CI, 1.0-3.4). A sensitivity analysis that classified exposures assuming lower well-pumping rates showed similar results.Conclusion: We investigated the hypothesis generated by earlier spatial analyses that exposure to drinking water contaminated by wastewater effluent may be associated with breast cancer. Using a detailed exposure assessment, we found an association with breast cancer that increased with longer latency and greater exposure duration. Editor's SummaryPrevious research suggested a possible link between breast cancer and groundwater plumes in upper Cape Cod, Massachusetts. However, the geographic relationship between breast cancer clusters and groundwater plumes alone does not establish exposure. To test the hypothesis that drinking water contaminated by municipal wastewater effluent from a specific source is associated with breast cancer, Gallagher et al (p. 749) integrated residential histories, public water distribution systems, and groundwater modeling within geographic information systems to examine the association between exposure to drinking water contaminated by wastewater effluent and breast cancer. Exposure was assessed from 1947 to 1993 for breast cancer cases diagnosed from 1983 to 1993. The authors report that wastewater effluent affected the drinking water wells of study participants as early as 1966. Using detailed exposure assessment, the authors report an association with breast cancer that increased with longer latency and greater exposure duration.
Author address
Department of Environmental Health, and.
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