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The Greatest Medical Disaster that No One Talks About: The First Endocrine Disruptor

Published by Connealy, MD on January 14, 2025

The Greatest Medical Disaster that No One Talks About The First Endocrine Disruptor

A pill meant to save lives instead caused millions of cancer cases, birth defects, and lifelong health issues. Diethylstilbestrol (DES) is one of the most catastrophic examples of pharmaceutical, governmental, and medical failure—a breakdown of the very systems we rely on to protect us.

Despite its devastating legacy, the story of DES remains largely untold. It’s not taught in medical schools, rarely discussed in history, and absent from public discourse. Why? Perhaps because confronting the fallout of DES would force us to reckon with the pervasive role of estrogens in our modern world—whether in birth control, plastics, or the many endocrine disruptors we encounter daily.

For me, this story isn’t just historical—it’s personal. When my mother was pregnant, her doctor prescribed DES to prevent miscarriage, unaware of its long-term consequences. It wasn’t until I was 16 that I learned the full scope of its impact. MD Anderson contacted me about participating in research on prenatal DES exposure. That was the first time I understood what had happened before I was even born—and the lifelong implications it carried.

The story of DES isn’t just about the past; it’s a warning for the present and future. It’s a reminder that the systems meant to protect us don’t always succeed—and that the consequences can last generations.

My whole life I struggled with hormonal imbalances–I have never had 2 consecutive menstrual cycles in a row, had to go through fertility treatments, and in my 60’s underwent 16+ hours of back surgery for scoliosis, a condition tied to structural deformities that was caused by DES.


DES was the first synthetic estrogen, created in 1938 by British chemist Sir Charles Dodds. It was three times more potent than natural estrogen and cost just two dollars per gram to produce, compared to three hundred dollars for natural estrogen. Because DES was developed in a publicly funded lab, it couldn’t be patented. This opened the door for pharmaceutical companies to mass-produce and profit from it.

DES binds strongly to estrogen receptors in the body, triggering the same cellular responses as natural estrogen, such as cell growth and differentiation in reproductive tissues. Unlike endogenous estrogens, DES is not metabolized as quickly, leading to prolonged activation of these receptors. This overstimulation of these receptors causes an excess of estrogenic activity.

At the time, understanding of hormones was still in its infancy, and the medical community had only recently discovered that estrogen played a key role in pregnancy. Scientists theorized that miscarriages were caused by hormonal imbalances, specifically a lack of estrogen. DES, they believed, could artificially restore balance and stabilize pregnancy.

The problem? This theory was completely untested and based on little more than speculation. By the early 1940s, DES was fast-tracked for use in pregnancy, despite no concrete evidence that it worked—or was safe. The initial studies advocating for DES  as a miscarriage preventative were significantly flawed– the research conducted lacked proper control groups, making it impossible to determine whether observed outcomes were due to DES.

Regardless, in 1941, the FDA approved DES for use in pregnant women, and soon it was marketed as a miracle solution for any pregnancy complication, including prior miscarriage, bleeding, or diabetes.

A few months after synthesizing DES in 1938, Dodds published a paper demonstrating that DES could prevent and terminate pregnancies in rats and rabbits, suggesting its potential as a birth control or emergency contraceptive. He strongly opposed its use in humans, cautioning that the female reproductive system was too delicate to tolerate foreign substances. He also warned about the potential cancer risks associated with DES and other synthetic estrogens. Unfortunately, his warnings didn’t stop companies or doctors from promoting its use. 

In fact, doctors were urged to prescribe DES liberally, and pharmaceutical companies like Eli Lilly readily promoted its use. Lilly sent sales representatives directly to physicians’ offices, encouraging them to use DES for their patients. Reps assured doctors that DES was perfectly safe—even as evidence of harm began to surface. Between the 1940s and 1970s, an estimated 5–10 million people worldwide were exposed to DES, in the United States, Canada, Europe, and Australia. 

List of brand names of DES: https://desaction.org/brand-names/


It did not take long for researchers to start questioning DES. In 1953, the landmark Dieckmann study, published in the American Journal of Obstetrics and Gynecology, showed that DES was no more effective than a placebo in preventing miscarriages or preterm births. Pharmaceutical companies ultimately ignored the study, continuing to market DES aggressively for nearly two more decades. It did not matter if DES was ineffective as long as it was profitable. 

From the 1940s-1970s DES was used for:

  • Pregnancy complications
  • Morning-after pill
  • Lactation suppression
  • Menopause, PMS, and other menstrual disorders
  • Cancer treatment
  • Livestock growth promotion
  • Veterinary medicine
  • Acne treatment
  • Vaginitis treatment
  • Hypogonadism and ovarian failure

“DES was found in almost every aspect of American life, although researchers knew that it caused cancer and sexual dysfunction in experimental animals and their offspring. Not only was it widely prescribed as hormone replacement therapy, it was also given to pregnant women at risk for miscarriage. DES became so popular that it was prescribed for normal healthy pregnancies much like vitamin pills, although it was never demonstrated to have beneficial effects, and many women were never informed they were given the drug. DES was also used to treat numerous other medical conditions including breast and prostate cancer, stop production of milk after childbirth for non-nursing women, treat menstrual disorders, treat acne, and halt the growth of young girls considered at risk for getting too tall.” (Langston, 2010)

In 1941, Charles Huggins and Clarence V. Hodges at the University of Chicago began using DES to suppress testosterone, with the notion that testosterone feeds prostate cancer growth. Huggins was even awarded the Nobel Prize in Physiology or Medicine in 1966. Most ironically used to treat breast cancer from 1960-77, DES was later replaced by other therapies, including tamoxifen. 

In 1954, the FDA approved DES as a feed additive for cattle, chickens, and sheep. The estrogenic activity of DES promoted weight gain efficiency in meat production. In the 1960s it was estimated that 90% of U.S. cattle were treated with the hormone. 

“In addition, DES was quickly introduced into veterinary practice to treat infertility and mastitis in livestock, as pellets implanted into poultry and livestock and as feed additives for cattle to improve feed efficiency and promote rapid weight gain. Langston cites a report stating that, by 1955, > 90% of the livestock in this country was being given DES” (Newbold, 2010).

One of the most notorious DES-related incidents occurred in Italy during the 1970s. Residues of DES, used to fatten calves were found in veal that had been incorporated into baby food, inadvertently exposing infants to synthetic estrogen. Reports emerged of male infants developing gynecomastia (enlarged breast tissue), vaginal bleeding in young girls, and other hormonal disturbances due to DES contamination. In 1980, following public outcry, the European Union and FDA banned the use of DES in livestock.

During this period, unmarried women were often coerced into giving up their babies for adoption, driven by societal stigma against single motherhood. In one of the most unethical medical practices in the 20th century, many were administered DES to suppress lactation to sever the maternal bond. Women were often given the drug without their consent and without being informed of the risks. This practice, widespread in countries like Australia during the forced adoption era, compounded the emotional trauma of losing a child with the physical harm of exposure to DES, leaving lifelong scars.


In 1971, the first seismic proof of DES’s dangers came to light. Dr. Arthur Herbst published research in the New England Journal of Medicine linking prenatal DES exposure to clear cell adenocarcinoma (CCA), a rare cancer of the vagina and cervix in young women. This cancer was virtually unheard of in women under 30. 

Herbst’s work revealed the true scale of the disaster: DES didn’t just harm pregnant women; it crossed the placenta, disrupting fetal development. Prior to this discovery, it was commonly believed that the placenta served as a protective barrier, shielding the fetus from potential toxins.

Studies started linking DES exposure during pregnancy to glandular abnormalities in daughters, leading the FDA to advise against its use in pregnant women in 1971. Despite this, research that same year suggested DES could function as an emergency contraceptive, prompting off-label use.  

By 1975, the FDA ordered the removal of high-dose DES tablets from the market and mandated labeling changes to discourage its use as an emergency contraceptive. Although DES remained available for other medical purposes, its use during pregnancy persisted in some countries into the 1980s.

It wasn’t until September 2000 when DES was officially banned by the FDA. It is still used in veterinary practices today. 


DES Daughters:

The legacy of DES is devastating.  Women who were exposed to DES in utero, like myself are referred to as DES Daughters. DES Daughters face significantly increased risk of developing cancers in the vagina, cervix, and breasts, especially after the age of 40 (Palmer et al., American Association of Cancer Research, 2006). Up to 90% of cancer in DES daughters can be attributed to exposure to the drug.

DES daughters often have structural abnormalities in their reproductive systems. Studies, including the influential 1985 research published in the American Journal of Obstetrics and Gynecology, found that up to 75% of DES daughters exhibited deformities such as T-shaped uteruses, cervical hypoplasia, and vaginal ridges. These abnormalities significantly increase the likelihood of infertility, recurrent miscarriages, ectopic pregnancies, and preterm births. The structural malformations disrupt the normal architecture of the reproductive tract, making it difficult for many DES daughters to conceive or carry a pregnancy to term.


DES Sons: 

The effects of DES on sons have been gradually uncovered. Early concerns in the 1970s arose when higher rates of urogenital abnormalities were observed in men whose mothers had taken DES during pregnancy. Studies linked prenatal DES exposure to conditions such as epididymal cysts, hypospadias (a malformation of the urethra), and cryptorchidism (undescended testes). These findings were supported by a 1977 study published in the Journal of Urology, which documented abnormalities in the male reproductive tract and highlighted potential fertility issues.

Further research in the 1990s and 2000s examined the impact of DES on male fertility, with studies suggesting that DES-exposed men may experience reduced sperm count, abnormal semen quality, and testicular hypoplasia.


As for myself, at the age of 16, I was diagnosed with pre-cancer on my cervix. Growing up, I struggled with severe scoliosis. I never had two periods in a row and intense mood swings. I was unable to have children naturally and required hormone treatments. A few years ago, I traveled to Germany for two back surgeries, one of which lasted 16 hours. While the surgeries significantly improved my back, they left me with nerve pain in my leg, causing me to walk with a limp. I don’t share this to seek pity but to highlight the realities of the consequences of this drug. 


Today, DES survivors continue their fight for justice through lawsuits. While some have won settlements for the harm caused by DES exposure, the drug’s generational impact remains immeasurable, making it difficult to fully quantify the damage.

For more information on ongoing lawsuits: https://desaction.org/ 

List of attorneys who deal with DES lawsuits: https://desaction.org/lawyers/attorney-list/ 


DES was the first recognized endocrine disruptor. It’s a cautionary tale about the dangers of unchecked pharmaceutical and industrial practices. Today, we face similar challenges with chemicals in plastics like BPA, pesticides, and food additives. The lessons of DES are painfully relevant: we cannot afford to ignore early warnings or prioritize profit over safety.

DES is more than a medical failure—it’s a lesson in hubris. It’s what happens when doctors and pharmaceutical companies dismiss new research and ignore the harm they might cause.

The medical community trusted DES without sufficient evidence, and millions are still paying the price. There are far too many tragedies like this to justify blind confidence in any treatment or theory. Medicine must remain a field of humility and constant learning.

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