This week I have a slightly different essay for you. As the resident science nerd in my social group, I often distill  — in the least nerdy way possible, if you can believe — key learnings from recent health papers and podcasts. I thought I’d share the latest one with you, because it’s a doozy.

Plastics and pesticides are way worse than we all thought

Today we’ll be breaking down the newest pod on hormone-disrupting chemicals.

It will leave you wondering why the hell aren’t we screaming about this from the rooftops? 

But then you’ll do a ~little inventory~ of your own daily sources of endocrine disruptors and be overwhelmed by the sheer number. Before scuttling off to order a $500 water distiller and throw a metric ton of shit out of your kitchen and bathroom. 

Anyway, let’s jump right in, with some key points:

• We are exposed to a smorgasbord of endocrine (hormone) disruptors in our daily lives

• This is drastically impacting our fertility — so much so that in the future, medical-assisted reproduction may become compulsory

• Boys born to mothers with high exposure to endocrine disruptors during pregnancy have smaller penises and lower sperm counts

• These chemicals may also be affecting the way babies’ brains develop and impacting their behavior long term

• There are actionable ways to decrease our exposure, and I’ll list these

This podcast featured Dr. Shanna Swan, who’s spent most of her life studying endocrine disruptors and human fertility. She’s about to turn 89!, and she’s one of the sharpest minds you’ll ever have the pleasure of listening to.

Some housekeeping:

• This covers chemical endocrine disruptors, not lifestyle factors (like sleep and exercise)

• I’m not going to footnote and reference stuff, it’s all done here 

• This is a science-based topic and essay, and uses the terms female, male, and female-like, in the *biological sense,* okay!

Cool let’s go

we’re in a fertility crisis

And not just because many of us (hi) are choosing not to have kids. Male sperm count has plunged ~60% in the last 50 years. One in three Americans have turned to fertility treatments, or know someone who has. The percentage of babies born via IVF is rising each year. 

Something is not right.

That something is endocrine disruptors. They’re present in plastics and pesticides we are exposed to daily. 

But let’s start at the beginning of this scientific journey.

small rat penises

A few decades ago, a study found that pregnant female rats who had higher exposure to phthalates — very common chemicals used to make plastic more flexible and stuff like lotion more absorptive — gave birth to male rats with smaller penises. 

Interesting. 

Biologically, it makes sense, because phthalates interfere with testosterone signaling. And testosterone is vital for the development of male characteristics. So when phthalates messed with testosterone in the womb, some male rats were born with smaller penises, undescended testicles, and ‘incompletely masculinized’ genitals. 

Anyway scientists called this “phthalate syndrome” and, seemingly, kept it under wraps.

Until further studies went on to show that phthalate syndrome also occurs in humans.

The more phthalates a baby boy is exposed to in the womb, the smaller his penis is likely to be.

Now you might ask yourself, as I did, how are they going around reliably measuring phthalate exposure and tiny weenies? So for the curious:

Phthalates are metabolized and excreted in urine. Throughout pregnancy, women’s urine was collected and measured for these chemicals. And when their babies were born, doctors measured the boys’ anogenital distance — a replicable measurement that is directly correlated with penis size. 

Critically, anogenital distance (AGD) “is forever,” as Dr. Swan puts it. So the babies who had a shorter AGD at birth and infancy also had a shorter AGD as adults. 

Okay Shân but does this actually matter? Indeed it does. Because at reproductive age:

• Shorter AGD/smaller genitals mean lower sperm counts

• In men who are actively trying to conceive, shorter AGD/smaller genitals mean a lower conception rate and fewer offspring

Before every man reading this runs off to find a tape measure, let’s not lose sight of the point, which is: 

Pregnant women need to minimize their exposure to phthalates for the fertility of future generations. Otherwise, according to Dr. Swan and her team, the only way for us to reliably reproduce down the line will be IVF.

But actually, this is not just applicable to pregnant women. Because while we’re focused on fertility here, our endocrine systems are key for a bunch of things — so whoever you are, this shit matters. A lot.

but wait there’s more

Now this is where it gets really wild. In one of these phthalate-penis-fertility studies, researchers asked parents to fill out extensive questionnaires about the behavior of their male children. 

And after controlling for confounding variables, they found that babies exposed to higher phthalate levels during pregnancy developed into boys who displayed less masculine play. 

These kids were way more likely to engage in ‘female-like’ play such as dressing up, having tea parties, and playing with dolls.

This links to previous research done with frogs, showing that behavior and sexual preference can be influenced by exposure to endocrine disruptors during fetal development.

Now, I am not entering into a gender-based-masculine-feminine-sexual-orientation discussion here. I am going to briefly make three factual points:

1. Testosterone impacts the development of both the genitals and the brain

2. This is a huge reason why males and females have differences in their genitals and brains (science calls this ‘sexual dimorphism’)

3. Messing up testosterone signaling during pregnancy, through phthalate exposure, will therefore have effects on both the genitals and brain — and future behavior 

This has led scientists to believe that in utero exposure to chemicals such as phthalates may indeed impact our sexual preferences. Which, I don’t need to tell you, is truly insane. 

okay so what can we do

We all need to minimize our exposure to endocrine-disrupting chemicals. The above research focused on phthalates, but they’re one of many. BPA, BPS, and PFAS also disrupt our hormone systems. We’re exposed to them daily.

And yeah, we can shake our indignant fists at the corporations using these chemicals but at the end of the day, the onus is on us to make the necessary changes.

Obviously, focus on what you can do, which won’t be everything. 

But here are Dr. Swan’s recommendations:

1. NEVER HEAT PLASTIC. BPA and phthalates are added to plastic but are not chemically bound to it. They come out under heat and go into your food. So, use microwave-safe glass. Never leave plastic water bottles in the sun. Ditch all your plastic spatulas and non-stick pans. And that plastic Aeropress of yours? lol

2. Say cheers to cans. The lining of cans is the primary source of BPA. Yes, any can, from beer to soup. Liquid Death might wanna change that packaging.

3. Ditch plastic wherever possible. “BPA-free” doesn’t mean anything, because manufacturers just use BPS and BPF instead, and they’re just as bad. Switch to glass, stainless steel, ceramic, etc.

4. Buy organic food wherever possible. Pesticides contain phthalates to increase their absorption into crops. Organic foods contain less, or no, pesticides. 

5. Choose personal care products wisely. If you can smell it, it’s likely affecting your hormones. If it’s “easily absorbed,” it often contains phthalates. Use this free guide to find safer products.

6. Leave your shoes at the door. Dust contains many endocrine disruptors, including PFAS.

7. Avoid handling receipt paper. It’s packed with BPA/S. Decline receipts or ask for them to be emailed.

8. Water matters. Dr. Swan uses a countertop water distiller to remove endocrine disruptors and other chemicals from tap water. You could also use reverse osmosis filters, but they’re only available for home-wide filtration systems. You could buy reverse osmosis water in refillable glass containers, but this is a pain in the ass.

9. Don’t panic. If you’re concerned about your chemical exposure or are looking to conceive, it’s a good idea to take a simple urine test to check your exposure levels.

looking ahead

Despite decades of research, we’re only beginning to uncover the full story of endocrine-disrupting chemicals and their effect on human health and behavior.

In the future, Dr. Swan reckons chemicals in clothing, especially workout wear, will be something we pay a ton more attention to. Plus the chemicals used in building materials and furniture. 

In terms of business opportunities (because I cannot help myself), I think removing endocrine disruptors from people’s lives will become a service.

Take people starting a family. We’re already (rightly) becoming obsessed with nutrition during pregnancy. Add this data on endocrine disruptors, and most people won’t even know where to start. But they’ll pay big bucks to someone who’ll handle it all for them — and their unborn child. 

~

Footnote: While this was male-fertility-focused, Dr. Rhonda Patrick has some great female-fertility-focused content on endocrine disruptors and the data are just as damaging. 

~

If you found this helpful, click on this link to let me know and I’ll do more (I’ll keep track of how many clicks it gets). 

Thank you for reading! Please forward this to anyone who may be pregnant. Or looking to improve their hormone health. Or actually just everyone because WTF why isn’t this on every health website worldwide

If you liked this, you can sign up here.