Gender Benders & Endocrine Disruptors around You

By Elizabeth Lee Vliet, MD
Excerpted and condensed from It’s My Ovaries, Stupid, pgs. 83 – 107
Scribner, 2003

For years, I have been exploring the links between environmental chemicals and their effects on our endocrine system. These synthetic, hormone-like substances interact with the estrogen receptors in our body, sabotage our hormones, and increase our long-term risk of disease.

Other chemicals have mixed effects, acting on all of our hormone receptors. These endocrine or hormone disruptors have been found in the body fat and breast milk of humans throughout the world, and well as in terrestrial and aquatic animal life. They are often called gender benders, for reasons that will become apparent later.

Many of these chemicals—such as dioxin, DDT, PCBs, and others—have been linked with increasing rates of cancer and endometriosis. But there are ominous signs that they also damage ovarian function, contributing to the alarming rise in female infertility, ovarian cysts, PCOS, hormone-triggered depression and anxiety, premature ovarian decline or failure, and immune disorders.

What Are Endocrine Disruptors and What Do They Do?

Certain man-made chemicals can act like hormones in the body. Because they persist in the environment for decades or even centuries without being broken down, they are also called persistent organic pollutants, or POPs. POPs pack a whollop to our endocrine system and our bodies: They may accentuate or disrupt, or completely alter or even block the actions of multiple body hormones, and not just estrogen.

Since POPs can mimic or block testosterone, thyroid, insulin, or other hormones, they fit under the broader category of “endocrine disruptors” and can affect anything in our body that is governed by hormones, which means just about everything! There are already hundreds of known POPs, and potentially thousands more.

Diethylstilbestrol, or DES, is a case in point. DES is a highly potent estrogenic compound that was first synthesized in Britain in 1938. Believing that it would prevent miscarriages, doctors subsequently prescribed DES to over 5 million women in the United States, Europe, and Latin America.

Later, DES was even more widely used, with the idea that it would create healthier pregnancies and stronger, healthier babies. Its application was further expanded to include emergency “morning after” contraception, to suppress milk production in women who did not want to nurse, and for treatment of menopausal symptoms like hot flashes. It even became a way to stop growth in teenage girls who were becoming “too tall!” DES was added to animal feed to fatten livestock and given to chickens speed their development. Human ingenuity compiled an absolutely staggering list of uses for DES.

Some Health Consequences of DES

DES Daughters

• Deformed uteruses, fallopian tubes, and ovaries
• Lowered egg production
• Higher rates of infertility, ectopic pregnancies, miscarriages, and premature babies
• Higher rates of endometriosis, uterine tumors, breast tumors, and pituitary tumors
• Increased frequency of ovarian cysts and abnormal follicles  Immune system problems
• Abnormal glucose tolerance and glucose utilization
• Abnormal development of gender-specific sexual behavior in DES offspring (feminized males and masculinized females), suggesting that DES caused abnormal sex differentiation during fetal development

DES Sons

• Increased genital defects, undescended testicles, and stunted testicles and penises
• Low sperm counts, abnormal sperm, and reduced fertility
• Higher rates of testicular cancer at earlier ages
• Immune system problems
• Abnormal glucose tolerance and glucose utilization
• Abnormal development of male sexual behavior

Clearly DES, and more broadly all POPs, can cause a wide range of serious health problems. But it is their specific ability to interfere with sexual development and gender-specific behavioral function that has earned them the dubious distinction of being called “gender benders.”

Why Are Endocrine Disruptors Such a Problem Now?

The short answer is that none of these organic compounds existed before the 1930s. Most have been invented in the “chemical age” that started just prior to WWII. During the period from roughly 1970 through the 1990s, the first human generation ever exposed to DDT and other POPs during fetal life began reaching their own reproductive age. Subtle disruptions began to appear.

Timeline of Synthetic Endocrine Disruptors (POPs)

• 1929: Polychlorinated biphenyls (PCBs) are developed
• 1930s: “Nerve gases” is developed in Germany and later used by the Nazis in WWII; these later became the basis for pesticides
• 1938: DDT is first synthesized and manufactured. DES, the first synthetic estrogenic compound, is produced
• 1940—1945: First widespread use of synthetic chemicals worldwide and widespread exposure to living organisms
• 1940s—1950s: First human generation exposed to synthetic chemicals in infancy
• 1940s—1970s: DES is in widespread use during pregnancy; first human generations are born after being exposed to synthetic estrogenic chemicals, pesticides, and other industrial pollutants (POPS) in the womb
• 1970s—2000: Health problems with DES children become manifest
• 1970s—1990s: First human generation to have been exposed to POPs in the womb is now reaching reproductive age when hormone disruptions become more pronounced and noticeable
• 2000: Second generation DES sons and daughters are now old enough for adverse health effects to be manifest

Where Are Chemical Endocrine Disruptors Found?

Simply put, they are now everywhere. Man-made endocrine disruptors, or POPs, are found in the plastic linings of canned goods, plastic food wrappers, detergents, herbicides, hair dyes, cosmetics, cigarette smoke, and auto exhaust—to name just a few sources. They may even be found in the water we drink, the food we eat, and the air we breathe.

They are also unwittingly added to the environment. Substances that are flushed down the toilet or rinsed down the sink can end up in the water supply, bubbling up in rivers and streams. A U.S. Geological Survey on 140 waterways in 30 states tracked 95 different pollutants, with some surprising results: 74% of the samples contained insect repellents; 48% contained antibiotics; 40% contained reproductive hormones (e.g., birth control pill estrogens and progestins); 32% contained other prescription drugs; and 27% had chemicals used for fragrances. So you may want to think carefully about how you dispose of your old prescriptions!

Since POPs are fat soluble, they become concentrated in the fat tissues of fish, animals, and humans. Anyone or anything at the top of the food chain accumulates the most POPs in body fat because each step in the sequence adds a little more of the pollutants to fatty tissues.

Mechanisms of Endocrine Disruption

Environmental chemicals that mimic hormones may act is several different ways to disrupt normal body function. They:

• Duplicate normal hormone responses but produce slightly different variations
• Interact with receptors to block normal hormone function, to produce an abnormal response, or to exaggerate hormone effect
• Interrupt normal signaling mechanisms that control our body’s ability to make proteins, enzymes, and other hormones
• Alter genes that control critical pathways. An example is the Y chromosome, which has to be turned on at a certain time in development to determine the “maleness” of an embryo. If an endocrine disruptors block the gene that acts as a switch, a male embryo is destined to live out his life in a hormonal and physical “limbo land,” medically called intersex
• Interfere with neurotransmitters, causing a disruption in menstrual and reproductive cycles
• Direct toxic effects on the nerve cells in the pituitary, the ovaries, and the testes
• Bind to hormone receptors on sperm and oocytes (cells that become eggs) to cause abnormal function and impair fertility

Suggested Reading

• Our Stolen Future, by Theo Colburne, Dianne Dumbrowski, and John Peterson Myers
• Living Downstream: A Scientist’s Personal Investigation of Cancer and the Environment, by Sandra Steingrabber

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