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The Globe and Mail

What's the most misunderstood body part? Breasts

Cinders McLeod / The Globe and Mail/Cinders McLeod / The Globe and Mail

After reading Breasts: A Natural and Unnatural History, by Colorado writer Florence Williams, you'll never look at mammaries the same way again: Evolutionary marvels. Pleasure domes. Toxic sponges.

Unnerved by reports of industrial chemicals in breast milk, Ms. Williams, then nursing her second child, had her own milk tested. The results shocked her, and kicked the environmental journalist into action. To understand what modern life was doing to her breasts, Ms. Williams interviewed leading biologists, anthropologists and medical researchers to create a fascinating portrait of this highly fetishized, but little understood, body part.

They're alive!

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The breast is the only organ that does all of its developing after birth, building itself out of nothing at puberty. Over the course of each menstrual cycle, breast volume varies by 13.6 per cent because of cell growth and water retention. And once a woman becomes pregnant, hormones trigger milk-making structures, which shut down and shrink after a baby has been weaned.

"For many women, we go decades and decades until our breasts really grow up, which finally happens during the final trimester of pregnancy," Ms. Williams says in an interview. It is only then, according to a theory she outlines in the book, that stem cells in the breasts "differentiate into cancer-resistant, high-performance dairy equipment … But when the stem cells are waiting around for decades for their dance card, they're either weaker or more likely to proliferate into cancer."

A blast of pregnancy juice

A woman who has her first child before the age of 20 has about half the lifetime risk of breast cancer as a non-mother, or a woman who waits until her 30s to have children. "Something about pregnancy rebuilds the breast and armours it, by changing the architecture of either the cells or the proteins around it," Ms. Williams says, adding that there is no consensus among scientists as to why or how this happens. "We know that pregnancy is protective, so there are some scientists thinking maybe there's a patch or shot a woman can get when she's 20 that will trick the breasts into protecting themselves," she says. "But we also know that using high doses of hormones can have unintended consequences, so it's not something to take lightly."

The canary in the human body

"We live in constant conversation with our air, our water and our food, and it turns out our bodies are more like trees than they are like temples," says Ms. Williams, who describes modern breasts as marinating in hormones and toxins. "We know that breasts get more tumours than any other organ in the body after skin, and I was interested, as so many people are, in the relationship between carcinogens and breast tissue." She also was fascinated by the breast's vulnerability to the latest man-made environmental villain, endocrine disrupters. Breasts, she writes, contain "a dense supply of receptors that sit on cell walls like hungry Venus fly traps, waiting around to catch passing molecules of estrogen, nature's first hormone."

Scarier than zits and mood swings

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Cancer researchers Drs. Jose and Irma Russo have discovered that puberty is a particularly bad time for cells to be exposed to possible carcinogens. "There are so many things that [girls]are vulnerable to at these ages and now it turns out their breast tissue is really vulnerable, too," says Ms. Williams, who has a daughter and a son. "It's a bad time to get X-rays, or do a lot of drinking and smoking. The cells seem to be more vulnerable to mutation when they're growing so fast."

Sour milk

"When we nurse our babies, we feed them not only the fats and sugars that fire their immune systems, cellular metabolisms and cerebral synapses," Ms. Williams writes. "We also feed them, in albeit minuscule amounts, paint thinners, dry-cleaning fluids, wood preservatives, toilet deodorizers, cosmetic additives, gasoline byproducts, rocket fuel, termite poisons, fungicides and flame retardants." These chemicals can linger in the body for decades. "The most efficient way to detox your body is to breastfeed and put those toxins in your infant," she says.

If that's not shocking enough, she writes in Breasts, "some of the chemicals we pass on to our daughters will stay in their bodies long enough for them to bequeath them to their offspring. Even if we cleaned up our planet tomorrow, the industrial detritus of the last generation has created a three-generation problem."

Nothing to see here

"I was surprised to learn that in toxicity testing of chemicals required by the government, often the mammary gland is not tested," Ms. Williams says. "It's thrown out. And the lab animals they use are tested as adults or as infants, but puberty is not considered a standard time to test an animal for toxicity. But from the breast's perspective, that's when they should be tested."

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Beware of the couch

Ms. Williams doesn't smoke, gets regular exercise, buys mostly organic food, has a three-stage reverse osmosis filter on her taps and doesn't heat plastic in the microwave. So she was confident she wouldn't have an elevated level of flame-retardant chemicals in her bloodstream. She was wrong. "It's a funny world when you have to biopsy your furniture," she says, after discovering a new generation of flame retardant called TDCPP (classified by the U.S. Environmental Protection Agency as a moderate cancer hazard) in the cushions of a new couch. "It does make me mad that so many items in our homes are dripping with flame retardants when there's really no evidence that they actually save lives in a fire. Why live with the uncertainty of what these endocrine disrupters can do to our bodies if we don't need to?

The breast course of action

"We live in a crazy world, and we can make ourselves over-anxious by worrying about every single thing. Ultimately, our personal choices don't make a lot of difference; it's more about our genes and the environment," says Ms. Williams, who jokes about packing quinoa in her kids' paper lunch bags. "Women and mothers can be powerful politically and become strong advocates for getting chemicals out of breast milk and making safer chemicals in the first place." And this is a cause with built-in male appeal. "Everyone likes breasts, so we need to work together to protect them."

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