Endocrine disruption caused by xenoestrogens is one of the most insidious and harmful health issues affecting young people today.
In Part I of this article series you’ll learn about the sex hormones, the endocrine system, xenoestrogens and why these chemicals pose such a serious threat to you and your unborn children.
WHAT ARE HORMONES?
Hormones are master regulator chemicals. They are produced by different organs in the body and travel through the bloodstream to regulate a wide range of essential functions like sleep, metabolism, digestion and the stress response. You may have heard of such hormones as insulin, growth hormone and thyroid hormone.
Hormones are made and secreted under the strict control of the endocrine system. The endocrine system has the unique job of ensuring the right amounts of hormones are acting at the right places at the right times.
Think of series of on-off switches coordinating a very complex traffic light system, with each tiny switch affecting other switches that in turn affect the flow of cars in a busy intersection. If the wrong lights are turned on at the wrong time you can get pile-ups, slow traffic flow or gridlock.
Specific hormones regulate sexual development and sexual function. Without these hormones, we wouldn’t be able to reproduce.
WHAT ARE ESTROGEN AND PROGESTERONE?
Estrogen comes in a variety of different forms. The most common and important is estradiol and it is made in the female ovaries.
For unborn babies, estrogen is essential for normal growth and development of the uterus, vagina and female reproductive tract.
During puberty, estrogen supports the development of typical female sexual characteristics. It is necessary for proper growth of breast tissue, widening of the hips, and the typical female fat distribution.
During a woman’s adult reproductive life, estrogen supports growth of the lining of the uterus (endometrium), and helps prepare the female body for ovulation and pregnancy.
During pregnancy, estrogen made by the placenta is essential for increasing blood flow to the growing uterus, placenta as well as preparing the breasts for breastfeeding.
Men also make make small amounts of estrogen which helps the normal maturation of sperm in the testes. However, estrogen is maintained at a much lower level in men compared to women, and much lower than the male hormone, testosterone.
Progesterone is also produced by the ovaries and is a key pregnancy hormone. During the female reproductive cycle, it prepares the uterine lining for implantation of the egg. It supports the growing fetus and assists in development of the female breasts for milk production.
Progesterone takes a back seat to estrogen in this story, however an unbalanced ratio between the two (known as estrogen dominance) is a contributory factor in many gynecological and hormonal problems.
WHAT IS TESTOSTERONE?
Testosterone is the primary male sex hormone. It is made in the testes.
For unborn babies, testosterone is responsible for normal development of the penis, scrotum and male reproductive tract.
During puberty, testosterone promotes development of male sexual characteristics including growth of sperm-producing tissues in the testes, enlargement of the penis, increase in muscle mass, deepening of the voice, growth in the jaw, brow and chin.
In adult men, testosterone is essential for the production of sperm. It is also necessary for maintenance of lean muscle mass, bone density and mood.
Low testosterone (also known as androgen deficiency or hypogonadism) is defined as a total serum testosterone level < 300ng/dL1. Testosterone deficiency occurs when low testosterone is accompanied by a range of undesirable symptoms and signs including erectile dysfunction, low libido, fatigue, anxiety/depression, hot flushes, increased body fat, metabolic dysfunction2, loss of bone density and reduced sperm counts3.
Women also maintain a natural level of testosterone, lower in proportion to the female sex hormones. Similar to men, women require testosterone for healthy libido, cognition, bone density and mood4.
WHY ARE THE SEX HORMONES CRITICAL FOR DEVELOPMENT?
As we grow from fetus, to infant, to child to adolescent to adult, the timing and amount of sex hormone exposure dictates whether sexual development proceeds normally or abnormally. Exposure to excessive estrogen signals or inadequate testosterone signals at critical time periods has the potential to irreversibly disrupt normal sexual development.
WHAT ARE XENOESTROGENS?
Certain types of chemicals in our food and environment can actually mimic the effect of estrogen in the body. These are called xenoestrogens (ξένος Greek, ‘foreign’) or estrogenics.
Xenoestrogens are just one class of chemicals known as endocrine disrupting compounds (EDCs), or endocrine disruptors. An endocrine disruptor is any chemical or mix of chemicals that interferes with normal hormone actions of the endocrine system.
Some xenoestrogens are naturally occurring plant or fungus compounds and are found in certain foods (e.g. soy). Most are man-made, including chemicals found in plastics, herbicides, artificial fragrances, cosmetics, medications (e.g oral contraceptives), industrial byproducts, metals and a wide range of daily household products.
Some of the most notorious endocrine disruptors you have have heard of include bisphenol-A (BPA), polychlorinated biphenyls (PCBs), diethylstilbestrol (DES), phthalates, paraben, and atrazine. We’ll explore the specifics of these substances in future articles.
HOW DO XENOESTROGENS WORK?
Many xenoestrogen compounds are chemically similar to the estrogen molecule and therefore bind to the estrogen receptor the same way as naturally-produced estrogen. The obvious consequence is excessive estrogen signals within the body. Unfortunately, your body cannot tell the difference between naturally-produced estrogen and these impostor xenoestrogen compounds.
But that's not the only way these damaging chemicals can mess with the switches of the endocrine system. Many have an anti-androgen effect, meaning they block both the production and the signalling of the male sex hormone, testosterone.
GENERAL EFFECTS OF XENOESTROGENS AND ENDOCRINE DISRUPTORS
Like detectives piecing together evidence of a crime, researchers have used animal experiments and long term human observational studies to clearly demonstrate the harmful effects of a range of endocrine disrupting chemicals.
But we still do not know the full extent of the harms of these compounds, mostly because the damage done to healthy reproduction in humans can take decades to be fully recognized. Let’s take a look at how these chemicals might be affecting you and your family.
EFFECTS ON MEN
As you might guess, repeated or continuous exposure to xenoestrogens that excessively signal estrogen and disrupt testosterone will reduce your testosterone level. You may also suffer the symptoms and signs of low testosterone mentioned previously (sexual dysfunction, mood disorders, hot flushes, increased body fat, loss of bone density and reduced sperm counts) but also signs of feminization including breast growth (gynecomastia).
Reduced semen quality is a particularly concerning effect of xenoestrogen exposure. Phthalates suchs as di-2-ethylhexyl phthalate (DEHP) and di-butyl phthalate (DBP), BPA and pesticide Dichlorodiphenyltrichloroethane (DDT) are just some of the endocrine disrupting chemicals proven to negatively affect the quality of semen, causing lower sperm counts (oligospermia), a higher proportion of deformed sperm and poorly motile sperm5.
Collectively, sperm counts amongst men in countries all over the world have been falling for the past 50 years6, at the same time as industrial xenoestrogen chemicals have increased in our food and environment.
In the 1960s, the lower limit of sperm quantity in men was 60 million /mL. This limit has been further lowered to 15 million/mL7, despite good evidence that fertility becomes meaningfully impacted below 40 million/mL8. Unfortunately, changing reference ranges of ‘normal’ male sperm counts do not change the underlying reality that male fertility is continuing on a downward trajectory.
So men, exposure to xenoestrogen chemicals has the potential to chemically castrate you, tricking your biology into making you more physiologically feminine and reduce your ability to reproduce.
EFFECTS ON WOMEN
The effects of xenoestrogens on women are no less concerning. By artificially increasing estrogen signalling, xenoestrogens disrupt the fine hormonal balance between estrogen and progesterone which required for a healthy menstrual period and normal ovulation.
Polycystic ovary syndrome and endometriosis have both been associated with exposure to BPA9 and phthalates10, both of which are potent xenoestrogens. Exposure to a class of flame-retardant chemicals called polybrominated diphenyl ethers (PBDEs) have been associated with both increased time taken to fall pregnant11 and increased risk of miscarriage12. Women with higher blood levels of BPA have similarly been shown to suffer increased likelihood of first-trimester miscarriage13.
Xenoestrogens can also negatively effect the length of women’s fertile life. Endocrine disruption by the phthalate class of plasticizer chemicals is associated with the Premature Ovarian Failure14, or the exhaustion of a woman’s egg reserves before the age of 40.
EFFECTS ON UNBORN BABIES
Endocrine disruption is particularly harmful during pregnancy, and specifically from 8-12 weeks of gestation, a period known as the Reproductive Programming Window. During this time baby’s genitals and the cells that will become its reproductive cells (sperm/eggs) are developing.
The baby is extremely vulnerable to hormonal disruption that can have irreversible long term effects on its sexual development and future fertility.
For male babies, the amount of testosterone present during this period will determine the size of its penis at birth. Exposure to xenoestrogen chemicals such as di-2-ethylhexyl phthalate (DEHP) or DDT will block the effect of testosterone and can lead to a smaller penis, as well as increased risk of undescended testes (cryptorchism), or a deformed penis (hypospadias)15.
For female babies, the negative effects of xenoestrogens are less clear, but exposure to various endocrine disrupting compounds including Diethylstilbesterol (see below) has been associated with abnormalities of the vagina, uterus and ovaries.
Most concerning, the effects of xenoestrogen exposure during pregnancy may not only affect your unborn children, but your children’s children and children’s children’s children. These are called inter-generational effects and occur through epigenetic changes to DNA. Consider the story of one of the most infamous endocrine disrupting compounds, a synthetic estrogen called diethylstilbestrol (DES).
DES was given to pregnant women in 1940s-70s to prevent miscarriage, in the mistaken belief it would ‘correct’ a supposed hormone imbalance. Not only was DES ineffective at preventing miscarriage, it turned out decades later that the daughters of women treated with DES were at massively increased risk of a rare type of hormone-sensitive cancer16. Vaginal clear cell adenocarcinoma was practically unheard of until it was discovered among these unfortunate young women exposed to DES in the womb.
But cancer wasn’t the only problem associated with this xenoestrogen chemical. These women had increased chance of abnormalities in the structure of their vagina, uterus and cervix that increased their chance of infertility17. Sons were not immune either. Male babies exposed to DES sons had increased risk of infertility, testicular cancer and abnormalities of their genitals and urinary tract18.
WHY ARE ENDOCRINE DISRUPTORS SO INSIDIOUS?
Unlike typical poisons, endocrine disruptors may not directly kill your cells. Standard toxicology practice that relies on ‘the dose making the poison’ simply doesn’t apply when it comes to these compounds19. Xenoestrogens can have hormonally active signalling effects at minuscule doses and synergistically act with other xenoestrogen compounds in a multiplicative manner.
Taken together, its easy to see how establishing a ‘safe’ dose of exposure for xenoestrogen compounds very difficult, if not impossible.
If you’ve followed along this far you’ve done well. Let’s recap.
A range of chemicals in our environment disrupt the hormones of the endocrine system and can
act like estrogen in the body
interfere and block normal testosterone signals
feminize men, disrupt natural cycles of women and cause infertility in both sexes
interfere with normal reproductive development of children andunborn babies
affect the sexual development and future fertility of your unborn child and future unborn generations
In short, these chemicals have the power to disrupt the most key features of our humanity: the ability to reproduce ourselves. It therefore makes sense to adopt a precautionary approach and reduce your family’s exposure to these chemicals as much as possible and especially during pregnancy and childhood.
Know that we are in a full-blown war against xenoestrogens and endocrine disrupting compounds which are ubiquitous in the food and the environment. The future of your family line hangs in the balance.
The Rest Is Up to You….
— RootCause MD
December 19, 2021
Thank you for reading Xenoestrogens and Endocrine Disruption — Part I.
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Countdown by Dr Shanna Swan
Estrogeneration by Dr Anthony Jay
Endocrine-Disrupting Chemicals: An Endocrine Society Scientific Statement, Endocrine Reviews. 2009 Jun; 30(4): 293–342.