A GIS-Based Model of Historical Pesticide Exposure on the Risk of Breast Cancer
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
Evaluate breast cancer risk due to exposure to specific hormone-related pesticides
Keyword(s): Geographic Information Systems (GIS), Chemical Exposures & Prevention
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.