Opinion: Hitting the gym or going to yoga? Your workout clothes could be doing more harm than you realize

Editor’s Note: Alden Wicker is an award-winning independent journalist and author of “To Dye For: How Toxic Fashion Is Making Us Sick — and How We Can Fight Back” (Putnam). She manages the website EcoCult and contributes to publications like The New York Times, Vox, Wired and The Cut. The views expressed in this commentary belong to the author. View more opinion at CNN.

In 2022, the Center for Environmental Health, a nonprofit consumer advocacy group based in California, tested sports bras, leggings, athletic shirts and other activewear and found high levels of the chemical bisphenol A (BPA) in those sold by Athleta, PINK, The North Face, Nike and Patagonia, among other brands. (CNN reached out to the companies for comment; a spokesperson for Athleta said the company was committed to safety standards, adding, “We believe the CEH claims have no merit and stand by our products and practices.”) This came just one year after the CEH found high levels of BPA in socks from over 100 brands.

This information spread quickly through women’s groups and group chats. As I was in the middle of researching my book “To Dye For: How Toxic Fashion Is Making Us Sick – and How We Can Fight Back,” my friends asked me how concerned they should be. My answer? Very concerned.

You might remember BPA from the baby-bottle scare more than a decade ago. Or you might recognize it from all the “BPA-free” water bottles and children’s products now on shelves.

BPA is an endocrine disruptor, meaning that it mimics or interferes with the body’s hormones. And as anyone with a thyroid disease can tell you, the endocrine system doesn’t just regulate your reproductive system, it regulates all the important systems in your body, including your immune system, your brain, your metabolism and your cardiovascular system.

It governs weight management and your energy levels, not to mention your skin’s appearance and your ability to fend off illness. More specifically, research has found correlations between BPA exposure and infertility, brain and behavior disorders in infants and children, lifelong health effects for babies exposed to it in the womb, breast cancer, endometriosis and polycystic ovary syndrome (PCOS) and even acne.

According to Oeko-Tex, the safe textile chemistry certification, BPA could have been used to produce polyester-spandex in socks and athletic gear for a variety of reasons: for antistatic and colorfast properties; as dye-fixing agents for polyester; or to produce fungicides, PVC or spandex.

But BPA is not the only endocrine-disrupting chemical found in fashion. There’s also its close cousins bisphenol S and F, which are increasingly used to replace BPA; plus lead, mercury and arsenic, which can be used in the dyeing process; alkylphenol ethoxylates (APEOs), which are surfactants often used in the scouring, dyeing and printing of fabrics; perfluoroalkyl and polyfluoroalkyl substances (PFAS), a class of chemicals that are so persistent they’re known as “forever chemicals” and are often used in clothing for water and stain resistance; and phthalates, which are used to make bendy, pliable vinyl for things like pleather skirts and clear shoe straps.

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Whenever someone tests a fashion product, they seem to find at least one endocrine disruptor. When H&M and IKEA collected secondhand clothing (not theirs) from around the world and had them tested, the results presented in 2021 showed that almost all the wool samples were found with APEOs, and the phthalate DEHP was detected in 1 out of 4 of the polyester samples.

And when the Canadian Broadcasting Corporation (CBC) tested 38 pieces of clothing — including children’s apparel — it found that 1 in 5 had elevated levels of toxic chemicals like lead, PFAS and phthalates. The clothes found with unhealthy levels of chemicals were from ultra-fast fashion brands Zaful, AliExpress and Shein; a toddler’s jacket and red purse from Shein exceeded Canada’s limits on the amount of lead permissible for children by almost 20 times and more than five times, respectively. (All three companies pulled the items in response and told the CBC they would be investigating further.)

“It is deeply disturbing … The children’s clothing, that’s the thing that got me,” North Carolina–based fertility doctor Ashley Eskew told me after I sent her the news. “That’s an especially high-risk population.”

Meanwhile, exposure to PFAS, a class of chemicals that includes an estimated 12,000 types — whether it’s from drinking contaminated water or working in certain occupations like chemicals manufacturing — has been linked to obesity, developmental issues, liver damage and several types of cancer, according to the US Environmental Protection Agency.

High amounts of PFAS have also been found in period panties by Thinx, which also finalized a $5 million settlement in a class-action lawsuit in June that accused the company of using and not telling customers about PFAS. (Thinx denied all the allegations as part of the settlement, saying it was not an admission of guilt.)

Industry folks often roll their eyes at these fashion tests. Fearmongering, they call them. Others have tried to argue that some of the chemicals in clothing fell within the legal and regulatory limits.

But here’s the thing about the limits on the amount of hazardous substances allowed in textiles: In the US, they’re largely voluntary limits set by the industry itself — some companies choose to follow them, and many do not. Federal regulations around hazardous substances in clothing are lax, largely centered around flammability, clothes manufactured within the US (which make up a very small percentage of the items we wear) and lead and phthalates, but only when it comes to children’s clothing. California, which has some of the most stringent state laws on chemicals, only requires a label to identify clothing that has hazardous substances.

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I found in my research that the set thresholds for certain chemicals are often based on shoddy science and best guesses. Furthermore, endocrine disruptors don’t follow the old adage, “The dose makes the poison.”

Traditional toxicology has always assumed that the smaller the dose, the less the harm. It follows that scientists can find an amount below which there’s no harm at all, implying that exposure from fashion isn’t something to worry about, even if your sweat is drawing substances out of the fabric onto your skin. But more and more researchers agree that there is no “safe” dose of endocrine disruptors. “Even small changes in the hormone level could have drastic changes in the biological effect,” Dr. Laura Vandenberg, an associate professor of environmental health sciences at the University of Massachusetts Amherst, said in a July 2022 National Institute of Environmental Health Sciences-funded podcast episode titled “The Dose (Doesn’t) Make the Poison.”

Just reckon with the fact that an amount of an endocrine-disrupting chemical so small as to be equal to a drop in an Olympic-size swimming pool can cross the placenta and measurably affect an embryo, and those changes can be permanent, according to the book “Count Down: How Our Modern World Is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperiling the Future of the Human Race,” co-written by Dr. Shanna H. Swan, an environmental and reproductive epidemiologist who has spent more than two decades studying the effects of hormone-disrupting chemicals on our health.

The doses we are talking about, at parts per billion, are absolutely the kinds you can come in contact with while wearing clothes containing these substances.

For example, research by Notre Dame professor Dr. Graham Peaslee shows that PFAS comes off of treated textiles at the parts-per-million level. That’s 1,000 times more. There’s evidence that damage caused by endocrine disruptors can be passed from both parents to children, increasing their risk of developing reproductive abnormalities and other health issues.

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The signs that something is very, very wrong with our reproductive health and endocrine systems are myriad.

According to Swan, the prevalence of women seeking fertility treatment in the US who had a diminished ovarian reserve — a low number of eggs to give in IVF — increased from 19% to 26% between 2004 to 2011, a 37% jump in just seven years. Miscarriage rates are also increasing by about 1% percent a year, and it’s not because we’re waiting longer to start families — the most dramatic fertility reductions are in young people.

Sperm counts have plummeted by more than 50% in the previous 40 years, and if the trend continues, the majority of couples will need an intervention to get pregnant. Swan put the blame squarely on “the ubiquity of insidiously harmful chemicals in the modern world,” and especially “chemicals that interfere with our body’s natural hormones.” (Some researchers have disputed Swan’s findings, arguing that conclusions about a potential “spermageddon” are overblown, while others have made the case that global fertility declines are due to socioeconomic factors and other factors including obesity or stress.)

Girls are maturing and getting their periods earlier. There’s evidence that conditions like PCOS, endometriosis and fibroids are becoming more common, and a 2021 study out of Spain showed women who reported high use of cosmetics like hair spray, face creams, hair dyes and lipsticks had higher levels of endocrine-disrupting chemicals, which is associated with a risk of endometriosis.

“I mention it at every single first patient encounter that I have, and they are like, ‘I had no idea,’” Eskew said of her advice to patients to detoxify to improve their chances of getting pregnant. “If we get a small amount from our food, and if we get a small amount from our clothes, and we get a small amount from our personal care products, then what does that look like at the end of the day? That additive effect, if you actually looked at that, then I guarantee that all of these things would be high enough to cause some sort of symptom and problem. But we’ve normalized that.”

It’s anecdotal, but Eskew has noticed that a lot of her patients have seen various health problems like fatigue, constipation and hair loss clear up in the process of detoxifying so they can start a family. “I definitely think that there’s a big link there,” she said.

So what can you do to protect yourself from endocrine disruptors in your clothing? There are a few strategies that will reduce your exposure, if not completely eliminate it. Avoid performance finishes, especially stain-proofing and water-resistant finishes, which are usually provided by PFAS unless otherwise stated.

Avoid synthetic materials whenever possible. For example, the advocacy group CEH found BPA only in polyester spandex blends, not in cotton products. (Never fear: There are at least a dozen fashion brands that produce majority-cotton leggings and sports bras.) Also avoid PVC products like cheap vegan leather shoes and fashion, which contain phthalates.

Avoid counterfeit and ultra-cheap fashion brands — the kind with gibberish names you come across on social media and marketplaces like Amazon and that ship straight to you from the factory. Look for labels like bluesign, Oeko-Tex and GOTS.

Wash all new clothing before you wear it in fragrance-free detergent and avoid the use of scented dryer sheets and fabric softeners.

Finally, if it smells bad, package it back up and send it back.

After all, you might be undoing the benefits of hitting the gym every day when your workout clothes could be doing so much damage to your health.