Your Lululemon and Under Armour are destroying your hormones & fertility

Your clothes are made of plastic and nobody told you

Hi, I’m Aastha and thanks for joining Live Longer World as I parse through the snake-oil in longevity. On Health on Easy Mode, you can see my exact collection of non-toxic health products I use (15+ categories including clean water, lighting, air quality, non-toxic kitchen).

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I threw away my polyester clothing. And switched to organic cotton.

Polyester clothing is literally wearable plastic. It’s not just a skin irritant, it might be contributing to the fertility crisis, hormonal imbalance, and reduced energy levels.

Roughly 60% of clothing is made from polyester and other synthetic fibers. Lululemon, Under Armour, Zara, Calvin Klein are all predominantly polyester. Testing on popular sports bras from Nike, Athleta, The North Face, and others found BPA levels up to 40x the safe limit under California law!¹ These brands are great for the booty bump and coolness factor. Not so great for your health.

This is what the modern human looks like. We eat plastic, drink plastic, breathe plastic, and now wear plastic too!

What’s the big deal with polyester clothing?

• Poor sperm health: Polyester traps heat. Tighter underwear and more heat are linked to worse sperm markers. In one study², 14 men who wore a polyester scrotal sling had zero sperm(!) within 5 months. And a 2024 study³ found microplastics in 100% of human semen samples tested. Enough for me to not want my husband to wear plastic down there.

• Disrupted hormone health: Polyester clothing carries phthalates, PFAS (forever chemicals)⁴, BPA⁵ and other finishing chemicals. These are endocrine disruptors - they mimic or block estrogen, testosterone, and thyroid hormones.⁶ A study of children's school uniforms found PFAS in 100% of products tested.⁷

• Loaded with PFAS and heavy metals: Water-resistant, stain-resistant, wrinkle-free, and performance finishes mean added chemicals like PFAS. Polyester is also commonly made using antimony (heavy metal) as a catalyst, and antimony can migrate from polyester textiles into sweat. Antimony is a possible carcinogen. What’s worse is that the antimony keeps leaching even after repeated washes.⁸

• Microplastics contribute to heart disease: A 2024 study⁹ found micro and nanoplastics in the carotid artery plaque of 58% of heart patients. Those with plastics in their plaque had a 4.5x higher risk of heart attack, stroke, or death over the following 3 years.

• Increased inflammation: Synthetic textiles are the dominant source of indoor airborne microplastics. It is estimated that you may shed up to a billion polyester microfibers into the air each year just by moving around. Indoor air contains roughly 6x more microplastic fibers than outdoor air, resulting in oxidative stress and inflammation.¹⁰ Investing in an air filter and opening your windows is worthwhile.

• Skin irritation: Polyester traps heat, sweat, and oils against your skin. Textile dyes and finishes, including formaldehyde (a Group 1 carcinogen used for wrinkle-free finishes), add chemical irritation on top of the physical discomfort.¹¹

So what did I do about it?

• For my undergarments, I only do organic cotton.

• For the rest of my clothing, I do organic cotton or cotton 99.9% of the time. Pact is my favorite - they are affordable and fashionable.

  • Cotton is a natural fiber so it doesn’t come with the same plastic problem. The catch with cotton is that it is the world’s dirtiest crop. It is loaded with pesticides and accounts for 16% of the world’s insecticide use. These chemicals get absorbed into the cotton and don’t necessarily get off your clothes by washing them. Organic cotton is worth the extra money if you can get it.

• Our bedding, blanket, pillows, mattress are all organic cotton or organic wool. Never sleep on polyester sheets. Sleep is when your body is repairing itself, and polyester can even hinder the charge of the mitochondria.

The rest of the post is for paid subscribers. I discuss:

• Other materials that are safe (bamboo is not as safe as you think)

• Why to never wear polyester while working out

• More tips I practice to reduce clothing toxicity

• How to mitigate risk from textile dyes and carcinogenic wrinkle-free finishes. It’s not just the materials that matter, dyes too contain chemicals.

• Safe certifications when picking clothes