142nd APHA Annual Meeting and Exposition

Annual Meeting Recordings are now available for purchase

A GIS-Based Model of Historical Pesticide Exposure on the Risk of Breast Cancer

142nd APHA Annual Meeting and Exposition (November 15 - November 19, 2014): http://www.apha.org/events-and-meetings/annual
Monday, November 17, 2014 : 9:30 AM - 9:50 AM

Carrie Tayour, MPH , Toxics Epidemiology Program, Los Angeles County Department of Public Health, Los Angeles, CA
Myles Cockburn, PhD , Department of Preventive Medicine, University of Southern California, Los Angeles, CA
A geographic information system (GIS)-based model of historical pesticide exposure, set in California’s Central Valley, the most agriculturally productive region in the United States, was used to evaluate risk of postmenopausal breast cancer from hormone-related pesticides in a pilot case-control study. Lifetime residential and occupational histories were geocoded and linked to the California Pesticide Usage Reporting System data combined with land use surveys to determine exposure to specific pesticides. Cases (N=155) were women diagnosed with breast cancer in 2007-8 from the California Cancer Registry and controls (N=150) were recruited from tax assessor and Medicare listings in the same geographic area from 2001-2011.

Compared to unexposed women, those exposed at both residence and workplace had an increased risk of breast cancer from exposure to chlorpyrifos, an estrogen receptor agonist (OR = 1.83, 95% CI: 1.02, 3.28). We found null associations for 1,3-dichloropropene and diazinon, two pesticides without known endocrine-disrupting effects that were included to evaluate the specificity of our model.

Although we observed only a modest increase in breast cancer risk for a selected group of estrogen-mimicking organochlorine insecticides (OR = 1.40, 95% CI: 0.89, 2.19), we found differential effects among women aged 55-64 compared to women aged 65-74 years. Younger women had an increased risk of breast cancer (OR = 1.65, 95% CI: 0.66, 4.15) compared to older women (OR = 1.10, 95% CI: 0.47, 2.59), and although this finding was not statistically significant, it is suggestive of an exposure window that warrants further study. Women exposed to exogenous hormone-like chemicals during critical periods of breast development may be important for breast cancer risk later in life.

 The GIS-based methods presented here provide a more comprehensive exposure assessment using historical data than has been done previously. Methods used in other epidemiologic studies of breast cancer risk and exposure to pesticides typically aggregate pesticides of varying toxicological properties. When we considered exposure to all pesticides combined, we also observed no increase in breast cancer risk, suggesting that less specific methods of measuring pesticide exposure are biased towards the null.

Learning Areas:

Environmental health sciences
Public health or related research

Learning Objectives:
Evaluate breast cancer risk due to exposure to specific hormone-related pesticides

Keyword(s): Geographic Information Systems (GIS), Chemical Exposures & Prevention

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: As an epidemiologist with the Los Angeles County Toxics Epidemiology Program, I have conducted studies and public health interventions aimed at finding and preventing the link between toxic exposures in the environment and adverse health outcomes. Concurrently, I am a PhD candidate conducting a pilot study of breast cancer risk from exposure to pesticides using a GIS-based model that I have helped to improve and expand its capabilities.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.