What Our Breasts Are Telling Us

When Florence Williams was breastfeeding her infant daughter a decade ago, she started thinking more about the mechanics of her body. A longtime science and environmental journalist, Williams began to delve into the purpose and function of women's breasts and to examine the chemicals that were reportedly found in breast milk. Her investigation would span years and would lead her to a dramatic step: testing her own breast milk and, later, having both herself and her young daughter evaluated for chemicals in their bodies.

The result: higher than average levels of the kinds of substances found in common consumer products, such as phthalates, triclosan, and BPA (bisphenol A). Williams and her daughter started a "detox diet," weaning themselves off perfumed soaps and other exposure risks. Her research became the 2012 book, Breasts: A Natural and Unnatural History, which won a Los Angeles Times Book Prize and an Audie audiobook award for general nonfiction.

Editor at Large Sarah van Gelder spoke with Williams about her book and how the environment affects breasts at every stage of life.

Sarah van Gelder: Are there any other organs of the body that go through as many changes?

Florence Williams: There really aren't. And the reason for that is because breasts are really the last organs in our body to develop. They really don't develop until the last trimester of pregnancy in adulthood, and so because of that, they're sort of undifferentiated for a long time. They go through these incredible cellular changes every monthly cycle and then, of course, every pregnancy. They're these incredibly dynamic organs, and then because of that, they are very influenced by the environment.

Evolution designed breasts to be responsive to the environment. They're full of estrogen receptors, which are the body's way of communicating with the outside world. Circulating estrogen tells the breasts when to grow in puberty. Estrogen tells our breasts when we're pregnant and when they need to start building the mammary glands, so they're very hormonally sensitive. Our world is filled with hormones and substances that mimic hormones.

van Gelder: One of the things I found fascinating about your book is that you actually test yourself to find out what kind of chemical body burden you're carrying around and what's going on with your child, as well. Why did you choose to essentially experiment on yourself and your daughter?

Williams: Participatory journalism appeals to me. I think it makes the science a little bit more human. I found out that there were a handful of chemicals that government scientists were looking at to try and figure out why girls were going through puberty earlier. A number of those chemicals could be tested fairly cheaply in urine. My daughter [then around 6 or 7 years old] and I both were curious about our body burdens for those chemicals. We worked with a nonprofit near Boston, the Silent Spring Institute. Their toxicologists walked us through a little study of our own.

van Gelder: What did you find?

Williams: We tested for three or four of these hormonally active chemicals, including phthalates, which are commonly found in products like paint and plastics; and triclosan, which is an antibacterial compound frequently added to products like soaps and cutting boards. We also tested for BPA (bisphenol A). We found out that we had higher than the U.S. average levels for some of these chemicals.

We worked with the toxicologists to try to reduce our levels by doing a "detox diet" and trying to reduce our exposures by avoiding products like scented shampoos and soaps. For some of the chemicals, such as BPA, it was quite easy to reduce our bodies' chemical loads. But for other substances, like the phthalates, we couldn't budge our chemical loads very much. So even though we try to control our exposures, we can only have so much impact on our chemical load because we don't really know where these exposures are coming from.

For me, this brought home the necessity for manufacturers and the government to take responsibility for keeping hazardous substances out of the marketplace. We cannot be totally effective gatekeepers for our own families.

van Gelder: When you went on that low-toxin diet and found that some chemicals weren't reduced, are those the chemicals that bioaccumulate? Whatever chemicals you've been exposed to over the years are just staying with you?

Williams: The chemicals that we tested for were detectable in urine. And those chemicals actually do not bioaccumulate. Our bodies metabolize them pretty quickly, like in a 24-hour cycle. We did that because they're cheaper to test for. The chemicals that bioaccumulate in fat you have to test by testing blood or breast milk. I tested myself, but not my daughter, for flame retardants and some pesticides.

I tested my breast milk when I was still breastfeeding my daughter, so that was a number of years earlier. I found that, again, I had above-average levels of flame retardants, which at the time were very, very pervasive in American consumer products. They've actually since been largely removed, or are in the process of being removed, from upholstered furnishings, for example, because of consumer concern and California being proactive about changing their flammability standards.

van Gelder: So you didn't know why you had above-average ratings?

Williams: No, I really didn't. I tried to find out where these flame retardants were coming from. Flame retardants have a signature sort of fingerprint, so you can tell by the molecular structure what kind of products they tend to be in. I had particularly high levels of flame retardants that are common in upholstered furnishings and also in consumer electronics, like computers. So we think that's where most of them came from.

van Gelder: What was it like for you when you realized that your breast milk that you were feeding to your babies contained these substances?

"They're these incredibly dynamic organs, and then because of that, they are very influenced by the environment."

Williams: Well, it was a big question mark for me. I realized that we don't know all that much about what they do to our health. There's been a lot of research since then, and what we're learning is not reassuring: These flame retardants, especially, tend to interfere with the thyroid hormone and thyroid hormone signaling. And of course, the thyroid hormone regulates all sorts of critical bodily functions, from metabolism to brain and neurodevelopment. What's encouraging is that when the marketplace changes, our bodies, pretty quickly, reflect those changes. So breast-milk levels of flame retardants are dropping quickly. When we change policy, we can really change our bodies. That's empowering and important to know.

van Gelder: You write in your book about men who end up having breast cancer because of environmental contamination. Are male breasts also so sensitive to the environment?

Williams: For a long time we didn't know the causes of cancer in general or of breast cancer. Women's breasts are governed by these monthly cycles, they're governed by pregnancy, and they're governed by menopause. So when women get breast cancer, it's hard to tease out what's going on. But when men get breast cancer, it's a much clearer picture for scientists. When a cluster started emerging on the Camp Lejeune Marine Corps Base, epidemiologists were quickly fascinated. If the men were getting cancer, it probably wouldn't be so hormonally mediated. So there might be a clear link to the chemicals.

The men getting breast cancer who lived on Camp Lejeune seem to have been exposed to a number of carcinogenic chemicals. And the men were unusually young when they were getting the cancers--in their 20s, 30s, and 40s. The average age for men to get breast cancer, which is still quite a rare disease in men, is about 70.

van Gelder: Are there signs that greater awareness about breast health is taking hold? What's the most promising response you're seeing?

Williams: Women are talking more openly about protecting the right to breastfeed in public. Celebrities like Beyonce are modeling breastfeeding, and Angelina Jolie is increasing awareness of genetic vulnerabilities. I wish we'd talk more about body image and social pressures for young girls, who today grow up expecting and wanting their breasts to look a certain way, and this in turn is feeding the plastic surgery beast. I'm hopeful, though, that this and other conversations are ripe to happen soon.