That's why Susan Teitelbaum, assistant professor in the department of community medicine at Mount Sinai School of Medicine in New York, and colleagues recently completed a study looking at the effects of household pesticides on breast-cancer risk among women on Long Island.
The study, published online Dec. 13 in the American Journal of Epidemiology, found an association between lifetime residential pesticide use and breast-cancer risk in a sample of 1,508 women diagnosed with breast cancer between 1996 and 1997, as compared to 1,556 random controls. The study asked the women to self-report their exposure.
The research is part of a larger initiative called the Long Island Breast Cancer Study Project, which investigated breast-cancer risk due to environmental exposures among women in New York's Nassau and Suffolk counties. United Press International spoke with Teitelbaum about what drove her research and the Long Island project.
Q. Why had no one looked at this topic before?
A. Pesticides have been studied extensively in occupational settings, since that's where you get the highest exposures. The Long Island Breast Cancer Study (Project) was specifically designed to look at the environment and breast cancer, and pesticides fall into environmental exposure. There was not a focus on breast cancer prior to this study; a law was passed to create this study in 1994. It takes a long time for epidemiological studies to get data collected, analyzed and published.
Q. Were you surprised by the findings?
A. We really didn't know what we would find when we began the analysis. The primary (aim) of the study is to look at blood samples and measure organochlorine (compounds) in the (study participants') blood. (Scientists have) reported an increasing risk (of cancer) with higher levels of DDT exposure.
If women were using DDT personally -- and lots of the pest problems that we ask questions about in that questionnaire were treated with DDT -- then initially you would expect we'd see an increased risk.
In the analysis of the blood samples for organochlorine, it was interesting to find women who reported using pesticides especially for lawn and garden problems did show an increased risk for breast cancer.
Q. Why was no association found with exposure to insect repellents or products to control lice, for example?
A. It's hard to know -- each of the problems is treated with different chemicals. Many pesticides have been identified as carcinogens, and others not. The (women's) exposure also may not have been very great, even if they used a pesticide.
Q. And you didn't see a dose-response?
A. We see an association. Our ability to measure exposure with just a report may not be sufficient to detect a dose-response.
Q. Why focus on Long Island?
A. The history of the Long Island Breast Cancer Project (involves) a very well-organized advocacy movement. Women on Long Island were very concerned about their high rates of breast cancer. They lobbied for having a study conducted to see what's going on. A public law was passed to have the Long Island Breast Cancer Study Project conducted. It was funded by both (the National Cancer Institute) and the (National Institute of Environmental Health Sciences). The case control study is completed (for the study), but data analysis goes on and on.
Q. Is pesticide use common? Can this be generalized to other places in the United States?
A. In all the women who participated in the study (there were) very few who reported absolutely no pesticide use. When we were trying to create a reference group -- a group not exposed -- what we had to do was take the lowest quarter of the women (who were exposed), since all women had some reported pesticide use. (So) pesticide use is very common.
Q. It seems it has infiltrated in our society.
A. (Yes, and there are) reasons -- you don't want ants in your house. It's the way life is. You (just) don't necessarily think about it until you ask questions like this. There has been a big movement to use alternative methods like (integrated pest management), which I think is great.
Q. How does your research advance this field of study?
A. Because no one looked at the relationship between residential pesticide (use) and breast cancer, and because we found it's the lawn and garden pesticide use that is related to an increased risk, what it can do is make people think about whether or not they need to use pesticide on their lawns, or to look for alternative methods. If you don't use pesticides, (their absence) is not going to affect your health. If in further studies (pesticides) are shown to be a risk factor, (at least) it is a modifiable risk factor.
Q. Is there a public health message?
A. I don't see why people who read this can't say, "I need to stop using pesticides."
Q. What are you doing next?
A. I am looking at various environmental chemicals, particularly endocrine disruptors, in relation to breast cancer.