Last week a friend of mine forwarded an Instagram story to me from a wellness influencer who was warning her followers against wearing clothing made from recycled bottles. Her theory was that, as a recycled plastic, rPET fabric contains harmful endocrine-disrupting substances that will interfere with your thyroid function and hormones.
It’s not so farfetched. It’s been well-reported that many types of plastics, including water bottles, have chemicals in them that can leach out, especially when water bottles are heated, like if you leave one in your car in the summer. Scientists have found high levels of antimony, a heavy metal and potential carcinogen, though not an endocrine disruptor, in disposable PET water bottles (the kind that are recycled into polyester). Most American-made PET plastic bottles do not contain the endocrine disruptor BPA, which has been linked to breast cancer — it’s more likely to be found in polycarbonate bottles like reusable squeezy sports bottles and food can lining. But that’s not a hard-and-fast rule. BPA has been found in Chinese water bottles, and since most polyester is manufactured in Asia (but not all) it’s possible that your recycled polyester leggings are made from this same type of PET.
In fact, experts recommend that you never reuse a disposable water bottle, because of these chemicals that leach out. But… can you recycle it and wear it and be OK?
Before I get into this, I want to direct you to a couple of readings. One is on whether recycled polyester clothing made from water bottles is sustainable. The other is about synthetic microfibers, which wash out of all synthetic fashion.
But for this one, I’m just going to focus on this question:
Is polyester made from recycled water bottles especially toxic to wear?
To answer this question, I turned to Dr. Martin Mulvihill, a researcher and advisor at the Berkeley Center for Green Chemistry, which he helped create and where he served as the founding initial Executive Director from 2010 to 2015. He’s now the co-founder and partner at Safer Made, a mission-driven venture capital fund that invests in companies and technologies that reduce human exposure to harmful chemicals. In other words, he is a foremost expert.
PET stands for polyethylene terephthalate. If you’re familiar with the world of toxic chemicals, you might have spied “phthalate” in there, which is another known endocrine disruptor. Why should you care? Because endocrine disruptors essentially mimic hormones in a harmful way, leading to thyroid issues, and potentially breast cancer and fertility and developmental issues in children. But, “It is important to recognize that terephthalates are not suspected to be endocrine disruptors in the same way that ortho-phthalates are,” Mulvihill says. They’re not one of the phthalates banned in the European Union, for example. And he’s seen no evidence that any phthalates leach into the water inside PET water bottles, much less leach out of PET polyester clothing wearing it.
He next cites the research I talked about above showing that antimony, which is used to manufacture PET, has leached into the water inside water bottles. It’s a heavy metal and suspected carcinogen, though not an endocrine disruptor. Manufacturers could use titanium instead of antimony to manufacture PET for bottles, but it’s more expensive and doesn’t work as well, so they don’t.
“But I am not overly concerned about it impacting human health,” he says. That’s because the research shows that it takes 38 days of a water bottle being heated to 150 degrees Fahrenheit for antimony to reach unsafe levels, and that is for water that you ingest, not fabric against your skin. The Chinese study on BPA released in water bottles indicated that BPA was even less of a problem at four weeks in 158-degree heat. And let’s be honest: if you’re in 150-degree heat while wearing your workout clothing, you have bigger problems than your hormones.
Finally, ever thorough in his answer (I love scientists), Mulvihill says that recycled PET could be contaminated with other plastics that do have endocrine disruptors. “That said, contamination severely impacts the quality of fiber, so a lot of time and effort goes to removing any non-PET contamination. The amount of contamination probably isn’t zero, but I haven’t seen any data to indicate it is a serious concern.”In conclusion, it looks like there is zero evidence that clothing made from recycled PET water bottles negatively impacts your health compared to other fabrics. Click To Tweet
“I think that this could be an example of how the public messaging around plastic = bad when it comes to food is having an unintended consequence,” Mulvihill concluded in his email.
Why you should care less about the material, and more about the finish.
The type of material does matter hugely when it comes to the environment: energy use, water use, land use, and how it’s disposed of. On that score, recycled polyester is way better than polyester made from virgin oil, especially if it encourages more recycling of plastic water bottles, and helps get them out of the environment.
But in terms of your health, what really matters is the substances that were put on the material, whatever it is. How was it washed and dyed? Are there any toxic finishes on it? If my biggest concern was toxicity, and you presented me with a 100% polyester blouse certified by Oeko-Tex, and an organic cotton blouse that was treated with formaldehyde to prevent wrinkles, I would absolutely choose the polyester blouse.
“In the end, many of us care about both human and environmental health, but I think it is worthwhile to make the distinction,” Mulvihill says. “From an environmental perspective, the rPET is a good thing, but we need to make sure it isn’t coated with harmful chemicals or antimicrobials before we declare it a good option for human health.”
So if you’re reading this because you’re pregnant, or you’re having thyroid, fertility, or reproductive health issues, then my advice to you is to look for companies that care about how their clothing is treated. For small brands, look for Oeko-Tex, GOTS, and bluesign certifications. For big brands, check to see if they’re a member of ZDHC, an industry group that prohibits manufacturers from using certain toxic substances, or Afirm, which helps brands test their products before they get onto shelves. Also avoid anti-microbial, anti-odor, anti-wrinkle, and (with one exception) anti-stain finishes.
If fancy athletic gear made from recycled bottles makes you feel good and motivates you to go for it! If you still would prefer natural fibers, there are a few options, too. Just make sure to check out our roundup of sustainable athletic brands, many of whom are completely non-toxic.