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Breast cancer risk in relation to occupations with exposure to carcinogens and endocrine disruptors: a Canadian case–control study

James T Brophy12*, Margaret M Keith12, Andrew Watterson1, Robert Park3, Michael Gilbertson1, Eleanor Maticka-Tyndale2, Matthias Beck4, Hakam Abu-Zahra5, Kenneth Schneider5, Abraham Reinhartz6, Robert DeMatteo6 and Isaac Luginaah7

Author Affiliations

1 Occupational and Environmental Health Research Group, Centre for Public Health and Population Health Research, University of Stirling, Stirling, Scotland, FK9 4LA, UK

2 Department of Sociology, Anthropology, and Criminology, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada

3 Education and Information Division, National Institute for Occupational Safety and Health (NIOSH), 4676 Columbia Parkway, Cincinnati, Ohio, 45226, USA

4 Queen’s University Belfast, University Road, Belfast, Northern Ireland, BT7 1NN, UK

5 Windsor Regional Cancer Centre, 2220 Kildare Road, Windsor, ON, N8W 2X3, Canada

6 Occupational Health Clinics for Ontario Workers, 15 Gervais Drive, Suite 601, Don Mills, ON, M3C1Y8, Canada

7 Department of Geography, Social Science Centre, University of Western Ontario, London, ON, N6A 5C2, Canada

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Environmental Health 2012, 11:87  doi:10.1186/1476-069X-11-87

Published: 19 November 2012

Abstract

Background

Endocrine disrupting chemicals and carcinogens, some of which may not yet have been classified as such, are present in many occupational environments and could increase breast cancer risk. Prior research has identified associations with breast cancer and work in agricultural and industrial settings. The purpose of this study was to further characterize possible links between breast cancer risk and occupation, particularly in farming and manufacturing, as well as to examine the impacts of early agricultural exposures, and exposure effects that are specific to the endocrine receptor status of tumours.

Methods

1005 breast cancer cases referred by a regional cancer center and 1146 randomly-selected community controls provided detailed data including occupational and reproductive histories. All reported jobs were industry- and occupation-coded for the construction of cumulative exposure metrics representing likely exposure to carcinogens and endocrine disruptors. In a frequency-matched case–control design, exposure effects were estimated using conditional logistic regression.

Results

Across all sectors, women in jobs with potentially high exposures to carcinogens and endocrine disruptors had elevated breast cancer risk (OR = 1.42; 95% CI, 1.18-1.73, for 10 years exposure duration). Specific sectors with elevated risk included: agriculture (OR = 1.36; 95% CI, 1.01-1.82); bars-gambling (OR = 2.28; 95% CI, 0.94-5.53); automotive plastics manufacturing (OR = 2.68; 95% CI, 1.47-4.88), food canning (OR = 2.35; 95% CI, 1.00-5.53), and metalworking (OR = 1.73; 95% CI, 1.02-2.92). Estrogen receptor status of tumors with elevated risk differed by occupational grouping. Premenopausal breast cancer risk was highest for automotive plastics (OR = 4.76; 95% CI, 1.58-14.4) and food canning (OR = 5.70; 95% CI, 1.03-31.5).

Conclusions

These observations support hypotheses linking breast cancer risk and exposures likely to include carcinogens and endocrine disruptors, and demonstrate the value of detailed work histories in environmental and occupational epidemiology.

Keywords:
Agriculture; Breast cancer; Canning; Casino; Carcinogen; Endocrine disruptor; Metals; Occupational; Plastics