Chemicals’ Role in Breast Development
A new report finds that chemicals can affect the development of mammary glands in fetuses and infants. Scientists believe these changes may lead to breast cancer. Bruce Gellerman talks with Dr. Marion Kavanaugh-Lynch, director of the California Breast Cancer Research Program, about implications for chemical testing in the future. (Photo: Steven Depolo, Flickr Creative Commons)
GELLERMAN: From the Jennifer and Ted Stanley Studios in Somerville, Massachusetts, this is Living on Earth. I’m Bruce Gellerman. There’s a lot we can learn about breast cancer from laboratory rats and mice. The latest research indicates some common chemicals - and maybe some foods - can act like hormones and disrupt the body’s delicate endocrine system during early development. They can alter how mammary glands grow later in life and increase the risk of breast cancer in women - and men. The results of these experiments on lab animals, conducted by the government and independent scientists, appear in the online journal Environmental Health Perspectives. Dr. Marion Kavanaugh-Lynch wrote the commentary accompanying the article.
KAVANAUGH-LYNCH: The studies tell us that exposure to chemicals, prenatally or early in life, can change the way the breast develops. And we think that some of those changes can then make you more susceptible to cancer later in life or can cause cancer later in life.
GELLERMAN: These are exposures to chemicals in fetal development.
KAVANAUGH-LYNCH: Fetal and, you know, the breast is kind of unusual as a human organ in that a lot of its development happens after birth. So the breast continues to change and develop in structure, in function, throughout infancy, adolescence, and then actually goes through more changes in a first pregnancy.
GELLERMAN: What kind of chemicals are we talking about here?
KAVANAUGH-LYNCH: So we’re talking about pesticides, such as atrazine; we’re talking about what are referred to as perfluorinated compounds, which are found in Teflon coating and stain-resistant coating; chemicals that are used in everyday products such as bisphenol A, which is used in the lining of many food cans and is found in many plastics and bottles; products that you can be exposed to without knowing it and be exposed to on a daily basis.
GELLERMAN: So it’s in natural products - foods!
KAVANAUGH-LYNCH: That’s correct - there are chemicals that can mimic estrogen that are found in commonly eaten foods, such as genistein and soy.
GELLERMAN: Genistein is what?
KAVANAUGH-LYNCH: Genistein is a compound that is found in high concentrations in green tea and also found in coffee.
GELLERMAN: So are you recommending people don’t drink tea, coffee, or eat soy?
KAVANAUGH-LYNCH: We’re not ready to make that recommendation at this time. There have been a lot of studies of the effects of soy and genistein on breast cancer, and what we know at this point is that the story is very complicated. You can have effects in early life that you then don’t see in adult life. And there could be even opposite effects between exposure in childhood, or in utero, and exposure in adulthood. In countries where people eat a lot of soy and consume a lot of genistein-containing products, the incidence of breast cancer is much, much lower than it is in the U.S. So we don’t know, for example if you don’t grow up eating soy on a daily basis, what the effect is if you start eating it as an adult.
GELLERMAN: What kind of exposures are we talking about here to these chemicals?
KAVANAUGH-LYNCH: We’re talking about exposures that are at lower levels than effects we see on other organs. So, for example, in many of these studies, the effects seen on the mammary gland happened at much lower doses than you see effects on other organs. And so the breast was actually the most sensitive organ to damage of any of the organs that were looked at in these animals.
GELLERMAN: Now when we talk about breast cancer, we commonly assume it’s females, but the researchers also studied males. Can men get breast cancer from these chemicals?
KAVANAUGH-LYNCH: We believe that they can. The incidence of breast cancer is much lower for men than for women - about a hundred times lower. But we actually think that they may be more susceptible to some of these chemicals, partly because women are exposed through their own bodies to hormones throughout much of their lives, whereas men in general are not. So it may be that they can be more sensitive to estrogenic-like compounds than women are.
GELLERMAN: So the obvious question is: if these things are ubiquitous, all around us, are these chemicals being tested adequately?
KAVANAUGH-LYNCH: We think they are not. In standard chemicals testing, it is not common procedure to actually look at the mammary gland of the animals that you are testing. And that is one of the things that the articles provide evidence for and that we are calling for - is that looking at the breast, or the mammary gland, in mice and rats is critical to help us understand these effects. If you want to find out what chemicals may cause breast cancer, you ought to be looking at the breast and the developing breast.
GELLERMAN: Am I right that there were studies done by the EPA that are included in this analysis?
KAVANAUGH-LYNCH: Yes, there are studies done by scientists who work at the EPA, in this particular field, included in this analysis, yes.
GELLERMAN: So federal regulators know about these effects?
KAVANAUGH-LYNCH: They do, it is true. Actually, worldwide, I think these effects are both known and have not yet been incorporated into governmental regulations at all. The European Union is quite a ways ahead of the U.S. in terms of regulating chemicals and requiring testing on chemicals. But even at this point, they’re not requiring examination of the mammary gland in early life in mice or rats in their studies.
GELLERMAN: Okay, so what are we waiting for?
KAVANAUGH-LYNCH: We’re waiting for the agencies to take notice of these effects and to consider it important enough to start incorporating into their everyday policies.
GELLERMAN: So what can I do - what can any of us do?
KAVANAUGH-LYNCH: As an individual, there are actually many things we can do. So one is we can try to reduce our own exposures to chemicals or other products that may be of harm to us. And work in your community to reduce community exposures, such as, for example, BPA - there's been fair amount of legislative activity, both on the state level and on the federal level, to remove BPA from at least some of the products that creates exposure for us. That can’t be the only action - a common phrase used among people who talk about this is, ‘we cannot shop our way to health.’ But we can demand better testing for chemicals and demand that the testing that is done include endpoints that are important to breast cancer. And then we can advocate for stronger regulation of these chemicals and removing some of them from our environment.
GELLERMAN: Well, Dr. Kavanaugh-Lynch, thanks so much, I really appreciate it.
KAVANAUGH-LYNCH: It’s my pleasure, thank you for inviting me.
GELLERMAN: Dr. Marion Kavanaugh-Lynch is director of the Breast Cancer Research Program in Oakland, California.
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