Skip to main content

A natural and unnatural history of, breasts

Q&A with Author Florence Williams

I had the opportunity to sit down with Florence Williams and discuss her new book Breasts: A natural and unnatural history, and how it relates reforming our out of date laws on toxic chemicals. I thoroughly enjoyed her book and thought it was a smart analysis of the scientific, cultural and chemical ways in which breasts have been shaped by modern life. Thank you to Moms Clean Air Force who granted me permission to re-post this Q&A from their blog. — Lindsay Dahl, Deputy Director

Why did you write a book about breasts?

I first got interested in this topic after my daughter was born. I was reading reports that there were industrial chemicals in breast milk. I had never really thought much about my breasts before I became a mother, but then they sort of amazed me, what they were capable of. When I found out about this research, I thought it would be interesting to tell that story using my own breast milk. So I sent it to a lab in Germany, which at the time, was one of the few places in the world where you could do these tests. It came back positive for trace amounts of a pesticide, and slightly above average levels of flame retardants. Then I set out on this journey to find out what that meant, for my health and for my daughter’s health.

From there, I became really interested in the field of environmental health, and learning how our bodies are kind of permeable. The way we treat our environment gets reflected back in our own cells. Breasts are very sensitive to the environment at every single life stage, from earliest embryonic development, through puberty and pregnancy and lactation and menopause. So it turns out that they’re really sentinel organs in our bodies.

Tell me more about the contaminants in your breast milk. What were they, and how did they get there?

The largest source of flame retardants in our bodies is dust in our homes. Many of the things in our homes are filled with flame retardants, from our upholstered furnishings to carpet padding to thermoplastics, like the casings of our TV sets and computers. We are exposed to the dust through inhalation, and probably ingestion, and even dermal contact. It also means I’m maybe a bad housekeeper!

But really, we all have these compounds in our homes. And if we’re worried about our breast milk having it, we should also be worried about our babies crawling around in it, whether they’re breast fed or not. For them, breast milk is just one exposure.

Did this lead to changes in your personal life?

It did lead to some. I feel like the impact is sort of superficial. Because really we are not going to be able to have a big impact until we change the way products are made. But there are some things I do. I often pack my kids’ lunches in cloth or in glass — but again it’s a little bit futile because I pull the carrots out of the plastic bag in the fridge.

Can we solve this problem by purchasing different products?

I actually don’t think we can, and it’s an unrealistic burden to put on individuals. Plus we don’t know where all our exposures are coming from, since products are not typically labeled with questionable endocrine disruptors. For example, I deliberately tried to lower my body burden of phthalates (which are added to personal care products) over several days in an experiment designed by the Silent Spring Institute. I could only lower them about 50 percent with some pretty extreme dietary and personal habit changes. This is why we need manufacturers to use safe chemicals to begin with, and why we need government agencies to test and regulate compounds in a meaningful way. Unfortunately, this is not currently the case.

What did you learn about the environmental links to breast cancer?

I learned that breast cancer is an incredibly complex disease that seems to have many factors contributing to it, some of which are environmental – and I’m including pharmaceuticals in that category. For example, women who take Hormone Replacement Therapy are at a higher risk of breast cancer. And many studies have shown that women who take birth control pills, especially the higher dose ones from several decades ago, seem to be at higher risk.

We know that there are many substances in our environment, some of which are pharmaceutical but some of which are industrial, that are estrogenic. So that is a logical place to look for possible breast cancer associations. There have been some intriguing findings. Women who were exposed to DDT as girls are at higher risk for breast cancer later on. The timing around puberty is a really vulnerable time for us in terms of exposure to carcinogens. We know that’s true of X-rays and radiation, and now we see it with some pesticides.

Some industrial chemicals have a multigenerational effect. When you expose a pregnant mouse to BPA, it alters the development of the mammary gland in her offspring. We’ve seen this in humans too with DES, which is a drug that was given to pregnant women for several decades before 1970. The daughters of those women given the drug are at higher risk for breast cancer as well as reproductive deformities, and their daughters now are also showing a higher rate of breast cancer. So we are seeing three generations so far of the effects of DES.

These breast cancer studies I would say are full of caveats. We need to have more studies and we need to be testing chemicals actually on mammary glands. Typically when chemicals are tested, even the few that are tested by our government, they are not actually looking at effects of mammary glands. They’re looking at effects on the liver and the heart and the brain. And those are all good endpoints to look at, but we know that the mammary gland is one of the most sensitive organs we have. It is the most common site for tumors in the body.

A lot of women agree that we have spent a lot of money on breast cancer studying the wrong things. We have put so much money into screening and treatment, and those are really important, but by the time you catch a breast cancer tumor on a mammogram, it’s too late. She already has the tumor. We need to prevent those tumors from growing in the first place.

What is happening with puberty?

The scientific consensus now seems to be after much discussion and controversy that breasts are developing younger in girls. To some degree this is biologically expected because girls are healthier now, and they have better nutrition, than they did before the industrial revolution. But the age of puberty is falling faster than it should be, faster than you would expect. Even since the 1970s it has fallen, and certainly infections and nutrition haven’t changed that much since then. Now one thing that has changed is rates of obesity. And it looks like there is some link between the age of puberty and body fat. But that also doesn’t seem to be explaining the entire phenomenon, so researchers are looking harder at other factors, some of which are social. For example, rates of divorce seem to affect age of puberty, and how much exercise girls get, and how much fiber they get. But scientists are also looking at these estrogenic chemicals in their diets and their households.

What should moms be doing about all of this?

I think that moms can be a really powerful group for change. When we found DDT in breast milk, that’s when we banned it. And when we found strontium, a radioactive isotope in baby teeth, again, that’s when we became more active in nuclear issues. Mothers can cross a lot of cultural and political divides. Everyone cares about breast cancer. Everyone cares about child health. These issues can be really unifying and powerful sources of change. I would encourage women to get informed and active. In fact, I think nothing is going to happen unless they do.

Take action NOW

Florence Williams is a contributing editor at Outside Magazine and a freelance writer for New York Times, New York Times Magazine, Slate, Mother Jones, High Country News, O-Oprah, W., Bicycling and numerous other publications. Recently she was a visiting scholar at the University of Colorado’s Journalism School. Her work often focuses on the environment, health and science. Her first book, BREASTS: A Natural and Unnatural History, was recently published by W.W. Norton. It was named a Notable Book of 2012 by the New York Times and nominated for the 2013 Los Angeles Times book prize.

Find her on Facebook at and follow her on twitter at