Earth to Harvard Med faculty: DES is not an 'endocrine disrupter'

A commentary in this week’s New England Journal of Medicine spotlights how easy it is to forget basic scientific principles even when you’re on the Harvard Medical School faculty.

In “The Long-Term Effects of In Utero Exposures — The DES Story“, Harvard faculty members Annekathryn Goodman, John Schorge, and Michael F. Greene (also an editor at the NEJM) attempt to label the now-banned synthetic estrogen diethylstilbestrol (DES) as an “endocrine disrupter” — just like enviro crank Theo Colburn tried to do with her 1996 book, “Our Stolen Future.” They wrote:

Chemicals that affect human fetal development are now called endocrine-disrupting chemicals, and an understanding of the changes caused by DES, the prototypical endocrine disruptor, has led to the identification of genetic pathways that govern the development of the reproductive tract… The lessons learned from the DES story are powerful. Endocrine disruptors may cause alterations in the reproductive tract that have severe consequences and form the basis of disease in adults decades later. Endocrine disruptors may come not only from ingested medicines, but potentially also from the environment through food. It is very difficult to recognize a teratogenic consequence of a prenatal exposure when the malformation does not manifest until 20 years later.” [Emphasis added]

First, DES was designed to be a hormone and it was. It was not some some treatment that inadvertently acted like a hormone or disrupted hormones. It functioned like it was intended. So DES is not an “endocrine disrupter” — especially as the enviros use the term.

DES was a drug that was administered in relatively high doses. In contrast, the endocrine disrupters of enviro fantasyland are manmade chemicals in the environment to which people are exposed to on a trace-level basis. There is no evidence that these have harmed anyone ever in a manner consistent with the endocrine disrupter hypothesis (a generous term for it).

It’s the dose that makes the poison and the therapeutic doses of DES administered to pregnant women turned out to be a poison for many. But the same is not so for manmade chemicals in the environment — or food, as the commentary’s authors intimate.

Ironically, Texas A&M researcher Stephen Safe compared the relative estrogenic activity in human exposures in a 1994 analysis. The highest — except for the birth control pill and hormone replacement therapy — was from the natural phytoestrogens in the diet. Synthetic chemicals, such as BPA were at much lower levels.

Drs. Goodman, Schorge and Greene should stick to teaching obstetrics and gynecology — and leave the junk science to others.

5 thoughts on “Earth to Harvard Med faculty: DES is not an 'endocrine disrupter'”

  1. What expertise do you have to counter the assessments made by these Harvard faculty? Can you elaborate on what you mean by “DES was designed to be a hormone and it was,” especially in terms of the lack of the four-ring chemical structure that all naturally occurring hormones exhibit? What is your understanding of the intended function of DES? In what ways did DES “function as it was intended?” What is your definition of “endocrine disruptor”? The Natural Resources Defense Council (self-defined “nation’s most effective environmental action group,” i.e. an “enviro” in your terminology), among many others, claim: “An endocrine disruptor is a synthetic chemical that when absorbed into the body either mimics or blocks hormones and disrupts the body’s normal functions. This disruption can happen through altering normal hormone levels, halting or stimulating the production of hormones, or changing the way hormones travel through the body, thus affecting the functions that these hormones control. Chemicals that are known human endocrine disruptors include diethylstilbesterol (the drug DES), dioxin, PCBs, DDT, and some other pesticides.” ( What “enviros” are you talking about? What exactly is the purpose of your post, in other words what’s the point of your dispute? Are you suggesting that “endocrine disruptors” as you define them pose no threat?

  2. Sarah, basic definitions aren’t hard to find.
    Endocrine Disruptor (
    DES ( I’m not going to copy them here.

    As Mr. Milhoy said, DES is a hormone. Calling it an endocrine disruptor is like calling dynamite “flammable”. Dynamite isn’t flammable, it’s explosive. DES isn’t an endocrine disruptor, it’s a homone treatment. Just as you cannot lump engine oil with dynamite, you cannot lump BPA with DES.

    And using this definition of endocrine disruptor, no, there has been no demonstrated health effect. There has been wild extrapolation, appeals to authority, and wild mass guessing, but no definitive evidence. This is why you cannot lump the two types of chemicals together.

  3. Ben, you are misinformed. Google BPA and DES to see what turns up. Here’s an article to get you started. All of these researchers are not wrong. But you are.

    New Haven, Conn. — Exposure in the womb to chemicals like Bisphenol-A (BPA) and Diethylstilbestrol (DES) can increase an offspring’s risk of breast cancer, researchers at Yale School of Medicine report in a study published in current issue of Hormones and Cancer, a journal of The Endocrine Society.

    BPA, DES and similar compounds are known as endocrine-disrupting chemicals, which are substances in the environment that interfere with the proper functioning of hormones. This disruption results in adverse developmental, reproductive, neurological and immune effects in both humans and wildlife.

    BPA is a weak estrogen and DES is a strong estrogen, but both have a profound effect on gene expression in the breast throughout life, according to lead author of the study Hugh S. Taylor, M.D., professor in the Department of Obstetrics, Gynecology & Reproductive Sciences at Yale School of Medicine. Taylor and his colleagues treated pregnant mice with BPA or DES and then studied the adult offspring. They found that the mammary glands in these offspring produce higher levels of EZH2, a protein that controls the expression of all genes. Higher EZH2 levels are associated with an increased risk of breast cancer in humans. The team demonstrated a mechanism by which endocrine-disrupting chemicals regulate developmental programming in the breast.

    “These results show that all estrogens, even weak ones can alter the development of the breast and place our children at risk,” said Taylor, who is also a member of Yale Cancer Center. “We many not be able to see the final effects of these exposures until our children reach the age when breast cancers start to appear.”

    “The data, coupled with our data on DES and BPA effects on the uterus, clearly demonstrate a lasting effect of prenatal exposure to estrogens on the breast and uterus,” Taylor added. “This study generates important safety concerns about exposures to environmental endocrine disruptors such as BPA and suggests a potential need to monitor women exposed to these chemicals for the development of breast lesions as adults.”

    Other Yale authors on the study include Leo Doherty, Jason Bromer, Yuping Zhou and Tamir Aldad.

    Citation: Hormones and Cancer doi: 10.1007/s12672-010-0015-9

    Contact: Karen N. Peart,Tel: 203-432-1326

    Source: Yale University

  4. I suspect Sarah that whether accidentally or deliberately you are acting as if a large distinction is a non distinction. BPA in the environment is not the same as DES administered deliberately in a large dose. I am sure the latter has a significant effect. Claims that BPA in the environment have similar effects on pregnant women has clearly not been shown and is frankly unlikely. Harvard Med school professors not withstanding. Six or seven orders of magnitude in dosage does make a difference.

  5. DES interferes with “normal” hormone action of the estrogen signaling pathway, leading to cancer in reproductive organs and other associated morbidities, thus it is classified as a disruptor, as, no matter its design, its end result is an alteration in normal estrogenic activity.
    The limits of the thinking behind what you write are truly shocking. I am wondering how much you might be paid by industry?

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