Endocrine Disruptors - From Evidence to Action

We hear a lot (though far from enough) about “endocrine disruptors” and their impact on our health, but how many of us really understand what they are and what their relationship is to our health? Given that we’re eating, breathing, and hosting them in our bottles, cups, cars, homes, foods, and worst of all, our bodies, you might like to know what they are. If you’re at risk for, battling, or determined to avoid cancer, you need to know. But wait. Consider the following quote:

“For too long, emphasis on what is called secondary prevention (detecting cancer early enough to treat it), has obscured the fact that detection of an existing tumor is not prevention. True prevention means identifying and eliminating the preventable causes of the disease before it can occur.” – (Breast Cancer Fund’s 2010 ‘State of the Evidence: The Connection Between Breast Cancer and the Environment)


If this quote strikes a chord of truth with you, then this 2-part blog is for you.

By the time we women give birth, if not long before, most of us have discovered just how sensitive our bodily systems are to our hormone levels. Change them ever so slightly, and our emotions can rage, our abdomens can scream in pain, our hair can fall out (or start growing in all the wrong places), we can suddenly gain or drop weight, sweat profusely, shake, or develop night-time routines of moon-watching or daytime routines of sleeping at random. Sometimes such fluctuations are part of the natural course of being or becoming a woman (think puberty, pregnancy, or menopause). Increasingly though, our hormones and our endocrine systems are responding to synthetic chemicals in our food, consumer products and environment, chemicals that have been developed so as to make our lives more convenient, chemicals that interact directly with our bodies’ hormonal processes. These chemicals are called Endocrine Disruptors (ED’s).


ED’s are synthetic chemicals that when absorbed into the body, either mimic or block natural hormones (especially estrogens) and disrupt the body’s normal functions. The disruption can happen through altering normal hormone levels, halting or stimulating the production of hormones, or changing the way hormones travel through the body, thereby impacting the functions that these same hormones control. ED’s include chemicals used as plastic additives, as product preservatives, in household cleaners, dry cleaners, industrial solvents, pesticides and herbicides, fire retardants, fragrances, petroleum jelly, baby oil, and most cosmetic and bodycare products. In a nutshell, they are everywhere in our modern, industrial societies. Why should we care?

A substantial body of peer-reviewed scientific literature implicates many of these chemicals in the current high rates of breast cancer. Scientists are proposing that the primary way in which ED’s affect breast cancer risk involves mimicking or disrupting estrogen or other endocrine pathways. As far back as 1991, researchers at Tufts University discovered that a chemical leaching from polystyrene laboratory tubes was causing breast cancer cells to grow in vitro (meaning IN THE TUBE), without them having added any estrogens to the culture. They found out that this common plastic additive behaved just like a natural estrogen with respect to breast cancer cell growth and division. Since then, the evidence implicating ED’s as cancer-promoting keeps growing.

Rather than run a complete list of the chemical culprits, let’s just consider three of the most common – Bisphenol A (BPA), phthalates, and parabens.


Bisphenol A:

Bisphenol A (BPA) is finally getting attention in the U.S. due to its use in baby bottles and plastic baby teething toys, in addition to a multitude of other products. Both the European Union and Canada banned its use in baby bottles in 2010. Important progress, but BPA still lurks everywhere.

Researchers at the Center for Disease Control have found BPA in nearly all of 2,517 urine samples taken from a broad national sample of adults. BPA has been found in the blood and urine of pregnant women, as well as breast milk soon after women gave birth. It has also been found in blood samples from developing fetuses and the surrounding amniotic fluid. So we modern day humans are being exposed to this powerful ED before we’ve even formed fingers and toes, and whether we’re breastfed or drinking formula from a bottle, it’s often part of our first and every meal. Fortunately, clearance rates for BPA are extremely rapid, gone with our urine within hours-to-days of absorption. More alarmingly, the fact that BPA is found so extensively in people and even people-to-be, from prenatal to adult age, despite this rapid clearing rate from our bodies indicates just how pervasive this stuff is in our environment.

In a study just published in Environmental Health Perspectives, five families were enlisted in a study in which they first ate their normal diets and had their blood BPA levels measured. They then passed three days eating only freshly prepared organic meals that avoided contact with BPA-containing food packaging, such as canned foods and polycarbonate plastic. Their blood BPA levels were again measured after 3 days on the control diet. They then returned to their normal diets. While the families were eating the fresh-food diet, their BPA levels dropped on average by 60 percent, while those with the highest exposure levels saw reductions of as much as 75 percent!

Now consider this. Recent studies have demonstrated that early exposure to BPA leads to abnormalities in mammary tissue development (breast tissue) that are observable while the developing fetus is still in the womb and that are maintained into adulthood! BPA has been shown to induce cell proliferation (pre-cancerous cell growth) both in vitro and in vivo (meaning in living mammalian bodies). Other studies indicate that the presence of BPA reduces the efficacy of some common chemotherapy agents. And that’s just one of hundreds or thousands of ED’s circulating in our blood, sitting in our fat tissue, and communicating with our cells.



How about Phthalates (pronounced ‘tha-lates’)? They’re in your water bottle, your yogurt containers, your plastic wrap and ketchup bottles, as they are used to make plastics soft and flexible. And what are they doing to us?

Phthalates have been found to disrupt the development and function of male and female reproductive systems. Abnormalities in male offspring exposed prenatally include nipple retention, shortened anogenital distance (the distance between the genitals and anus), and increased incidence of undescended testes. A recent study uncovered an association between shorter anogenital distance and a lower sperm count in men. Exposure of human mothers to phthalates, as measured by analysis of their
urine samples, has also been associated with shortened anogenital distances in their newborn sons – a measure of feminization of external genitalia in our newborn sons (Swan, 2005, cited in Breast Cancer Fund, 2010).

If all that isn’t alarming enough, a recent case-control study examined phthalate levels in apparently healthy girls who went through thelarche (breast development) before the age of 8 and found increased levels of a phthalate associated with the thelarche group but not the control groups. That’s scary if we recall that early breast development in otherwise healthy girls is associated with an increased risk for breast cancer during their lifetime.



Parabens are a group of compounds widely used as antimicrobial preservatives in food, pharmaceutical, cosmetic and body-care products. Parabens are absorbed through the skin and from the gastrointestinal tract and blood. Measurable concentrations of six different parabens have been identified in biopsy samples of breast tumors. Parabens have also reportedly been found in almost all urine samples examined from a demographically diverse sample of U.S. adults. Parabens are estrogen mimickers that can bind to cellular estrogen receptors. They also increase the expression of many genes that are usually regulated by estradiol and cause human breast tumor cells to grow and proliferate in vitro.


The sun is heating up in Florida, so I feel compelled to top off my list of 3 with a 4th source of concern – sunscreens. Many sunscreens contain chemicals that are not only estrogenic but lipophilic (meaning they’re stored in our fat tissue, not passed with urine). Researchers at the University of Zurich’s Institute of Pharmacology and Toxicology tested six common sunscreen chemicals and found that five of them exerted significant estrogenic activity as measured by an increase in proliferation of breast cancer cells in vitro and enlarged uterines in vivo.

What do I do with this information?


First, if this is all or mostly new information to you, take a deep breath. Do not despair. Knowledge is power, but does not necessitate instant life-altering actions. Making small and gradual changes can make a big difference in your and your family’s health. Informing ourselves is the most important step. The more of us making informed choices and voting with our dollars, the more health-protecting and affordable options there will be for all of us. Tune in for Part 2 of 4Women’s ‘Endocrine Disruptors – From Evidence to Action’ blog series for tips on taking your first steps toward a cancer prevention lifestyle.


For more empowering information on Endocrine Disruptors:

Cornell University’s Breast Cancer and Environmental Risk Factors

Breast Cancer Fund

Women to Women

(This blog was written by Michelle Young, Research and Communications Director at 4Women.com, a company that provides fashionable solutions to women and girls with medical hair loss and advocates for a better understanding of the emotional impact of medical hair loss.)


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