What are endocrine disruptors?

What are EDCs?

What are endocrine disruptors and why aren’t we freaking out over the endocrine disrupting nature of phytoestrogens?

Today’s episode is jam packed.  Originally intended to talk about the endocrine disrupting potential of some chemical sunscreens, it felt a bit disingenuous to leap into that conversation without a couple of primers on EDCs first, so this week and next we’re laying the groundwork.

This week, we’re covering what your endocrine system is, how endocrine disrupting chemicals aka endocrine disruptors aka EDCs aka endocrine disrupting molecules can interrupt the normal process, and we’re also talking about phytoestrogens and other naturally occurring compounds that act as natural endocrine disruptors.

My sincerest hope is that you walk away from this conversation with a new-found understanding of EDCs that maybe this term isn’t the four-letter word we’ve been led to believe and what all factors should be considered when determining which EDCs are good and bad for your health and how this shifts from childhood to adulthood.

What is the endocrine system?

Your endocrine system includes any gland or organ that secretes hormones.  Starting at your head and working down your body, these organs are your:

  • Hypothalamus
  • Pineal gland
  • Pituitary gland
  • Parathyroid glands
  • Thyroid
  • Thymus
  • Adrenals
  • Pancreas
  • Ovaries
  • Testes

Each of these organs and glands secrete at least one hormone and often these hormones are responsible for telling other organs in your endocrine system whether to scale-up hormone production or take a little break.

For example, your pituitary gland secretes thyroid stimulating hormone commonly referred to by the acronym TSH.  This hormone then signals your thyroid to generate the hormones T3 and T4.

Your pituitary gland also secretes luteinizing hormone, LH, and follicle stimulating hormone, FSH, two hormones that help regulate estrogen and progesterone production throughout your menstrual cycle.

Hormones do much more than just communicate with other endocrine organs.  Hormone receptors are found on many cells within your body, and hormones are one of your body’s ways of communicating with itself acting as messengers within your body.

Endocrine disrupting chemicals interfere with these hormonal messengers, and they can do this in a number of ways.

I’ll be using estrogen as an example as we look at the ways in which EDCs can interfere with your natural hormone messaging system.  Just keep in mind that estrogen is only one of the 75 hormones your body makes.  And, whether you’re male or female, each one of these hormones is important, and we’ll dive into why later in today’s conversation.

For now, let’s look at the ways EDCs can interfere with your body’s hormonal messaging system.

How do endocrine disruptors interfere with your body's hormones?

Direct disruption

EDCs might bind directly with the hormone receptor.  This is known as direct disruption.  For estrogen, the EDC may preferentially bind to either one or your two types of estrogen receptors.

Once bound to a hormone receptor, an EDC might mimic the hormone.  When an EDC bound to a hormone receptor mimics a natural occurring hormone, it instigates the same cellular response cascade that the natural hormone triggers.  The technical term for this is the EDC acts as an agonist.

An EDC might also cause a contradictory response.  In this case, the EDC blocks or counters the natural hormone’s response when it binds to the hormone receptor.  In this case, the EDC acts as an antagonist.

Depending on the EDCs binding affinity for the hormone receptor, the impact may be weaker or stronger than that of the hormone itself.

What are binding affinities for some common EDCs?

Let’s start by looking at the binding affinities for the 3 types of naturally occurring estrogens in your body. 

Estradiol is the most potent of the 3 naturally occurring estrogens in your body. It’s about 10 times more potent than estrone and depending on which study you’re looking at about 10 to 100 times more potent than estriol.

Estradiol is so strongly binding for both estrogen receptor alpha and estrogen receptor beta with roughly equal affinity for both that it’s generally assigned the maximum binding affinity or used as the reference molecule in binding affinity assays.

Now let’s circle back to the question what are binding affinities for some common EDCs?

PCBs are about 400 to 10,000 times weaker than estradiol depending on which PCB we’re talking about.  PCBs are a class of molecules known as polychlorinated biphenyls.  They're a persistent organic pollutant and their manufacture was banned in the US in the late 1970s due to health concerns and to their bioaccumulative nature.  They were once commonly used as coolants and in carbonless copy paper.  PCBs are so persistent that soil is commonly contaminated with them.

BPA is about 13,000 times weaker than estradiol.   The parabens most commonly used as preservatives are on the order of 100,000 to 300,000 times weaker than estradiol.

If these compounds are so much less able to bind to the estrogen receptor compared to estradiol, what’s the big deal?  Why do they raise such a level of concern?

Estrogen production by men and women

Both men and women naturally produce estrogen.  Men make about 40-50 micrograms of estradiol daily.  Women’s ovaries alone produce between 70 to 500 micrograms estradiol daily depending on the phase of your menstrual cycle.

Did you catch those units?  Micrograms?  A microgram is 1,000,000th (1 millionth) of a gram.  How much is a gram?  It’s just under ¼ teaspoon (1 teaspoon holds about 1.25 grams depending on the density of the material being weighed).  Men make between 0.00004 grams and 0.00005 grams estradiol daily while women’s ovaries make between 0.00007 grams and 0.0005 grams estradiol daily.

Care to guess how much phthalate you’re exposed to daily?  Studies predict your body is exposed to about 1 gram of phthalates every single day.  Phthalates can enter your body through the foods you eat, the drinks you drink, and because phthalates are volatile, they can also enter your body through the air you breathe.

If you’re a woman, even on your highest estradiol producing days, you’re still exposed to 2,000 times more phthalates daily through your environment than to your body’s own naturally occurring estradiol.  For men, that exposure level can be up to 25,000 times higher.

And, that’s just your expected daily exposure to a single class of man-made EDCs.  Speaking of phthalates.  Were you wondering why I didn’t mention their ER binding affinity?   

Phthalates don’t even register as binding to estrogen receptors… even DEHP.  Does that mean phthalates aren’t endocrine disrupting?  No, not by a long shot.  Estrogen receptors are just one type of hormonal receptor in your body and even though phthalates don’t directly bind or interact with your body’s estrogen receptors doesn’t mean they’re not affecting your hormones.

For your reproductive organs, phthalates work by binding to sex hormone binding globulin (SHBG), a protein that normally interacts with your body’s natural hormones dihydrotestosterone, testosterone, and estradiol.  So, phthalates still impact your body’s natural state of hormonal balance.

And, direct interaction with hormone receptors is just one way endocrine disrupting chemicals can interfere with hormonal regulation.

Indirect disruption

EDCs can work indirectly by speeding up or slowing down the generation and breakdown of naturally occurring hormones, in other words, EDCs can alter your body’s metabolism of hormones.

Natural endocrine disruptors

Why is your body made this way?

Have you ever noticed how your body responds when you bite into a ripe strawberry or take the first bite of your favorite sun-ripened fruit?

How about when you brush up against a lavender plant and the soft fragrance permeates the air?  Can you feel your body relax?  Some signals aren’t as profound as this aromatherapy example.  For instance, the color of sunlight at sunrise and sunset is different than mid-day, being more red at first light and as it sinks back below the horizon than in mid-day when its rays are more blue.  This color shift impacts your circadian rhythm.

Simply said we are creatures made to interact with our environment.  Our environment provides our mind and body signals and cues and these come in a variety of ways some so stark that our conscious mind notices and some far more subtle.

These environmental signals provide key information to your body and mind and many environmental cues are so subtle your conscious mind isn’t even aware of them. 

Many plant molecules, including phytoestrogens, belong to this class of environmental signals surrounding you at the subconscious level. 

These molecules are made to interact with your body or rather your body is made to interact with them in subtle ways, as gentle reminders that each one of us is so much more interconnected with our world than we can fathom.

Phytoestrogens are one group of plant compounds that interact with our bodies.  Phytoestrogens are endocrine disrupting, and we'll talk about the health implications of that and why you should reconsider soy formula for infants a few episodes from now.

Fragrance compounds of plants are another class of molecules that interact with your body.  Depending on how these fragrance compounds work, the fragrance compound can also be endocrine disrupting.  For instance, a quick way to reduce your cortisol levels is by smelling lavender or rosemary.

Endocrine disruptors is not a four-letter word. 

Many naturally occurring endocrine disruptors such as phytoestrogens and the aromatic compounds in essential oils can be good for your body and help regulate hormones (we'll talk about this a little more in a few weeks), and even some man-made aka synthetic EDCs can be beneficial to you in certain circumstances… a large number of drugs used to battle cancer belong to this class.

Unfortunately, the word EDC itself has become a dirty word and is now being used to warn people off phytoestrogens and certain herbs and holistic therapies.

And, I want to be crystal clear... many synthetic endocrine disruptors that we're exposed to through plastics, printer ink, coolants, and pesticides need to be banned because they are dangerous to your health and the health of the environment.  Here's why:

  1. they’re bioaccumulative, meaning they don’t readily break down in the environment so their concentration in the air or in the soil or wherever they persist increases over time
  2. many are volatile meaning they carry easily on the wind and can wind up in remote places
  3. they're produced in abundance... roughly half a billion pounds of phthalates were manufactured worldwide in 2006, and recent production levels of BPA exceeded 5 billion pounds per year worldwide
  4. these molecules enter the bodies not just of yourself and your loved ones,  but also wildlife and once inside, they unnaturally alter the natural hormonal pathways within your body, the bodies of your loved ones, and the bodies of the birds, fish, amphibians, crustaceans and mammals
  5. even if you do your absolute best to avoid products containing these synthetic endocrine disruptors, you're still exposed to some level of these on a daily basis because many are ubiquitous in the environment due to their inability to break down in the environment combined with their volatility and massive production quantities. 

    That's not to say you shouldn't try your best to limit your exposure to these compounds, it's just another way of saying we need to act beyond ourselves and push our regulatory bodies to implement stricter laws controlling these substances and demand truly safe alternatives.

As citizens of America, we’re routinely exposed to chemicals that have been banned in other parts of the world due to health concerns.  And, that’s the real story.  Regardless of whether these chemicals are classified as endocrine disruptors or are called for what they are, their:

  1. indestructibility
  2. high rates of production
  3. and in many cases their overwhelming links to health problems creates a solid case for demanding that regulatory bodies like the EPA and FDA step in with stricter regulations restricting these chemicals.

One of the greatest lessons from the pandemic is how agile companies of all sizes are, and when required, change happens. 

Next week’s a bonus episode.  We’ll be talking about two common EDCs.  One almost everybody in America is exposed to daily, and the second leads into my own personal story and some connections I’m only just now discovering.

Until next time,



https://pubmed.ncbi.nlm.nih.gov/17291597/ lavender and rosemary decrease cortisol level in saliva

https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/estrogen-receptors ERs are expressed either in cellular cytoplasm or in the cell’s nucleus





https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6151497/#:~:text=Ovaries%20are%20the%20major%20source,through%20aromatase%20actions%20(708).  Estrogens in male physiology







Brandy Searcy founder Rain Organica

About the Author

Brandy's a formulation scientist and self-proclaimed health geek who loves hiking, gardening, bird-watching, and body boarding. 

Her struggle with acne during her teens and 20s led to a holistic and healthy approach to skincare, embracing skin as an organ to be loved and cared for rather than a canvas to wage war on. 

Since 2008, she's been developing all-in-one products for a simple routine at home, & Rain Organica started when her backpacking friends asked for a portable skincare routine to keep their skin healthy & happy on and off the trails.

You can try Rain Organica for yourself with The Essentials Kit, a complete skincare routine in just 3 steps.

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