Most Bed Sheets Are Awash in Harmful Dyes. They Don’t Have to Be

When Michel May was studying in Japan 14 years ago, his mother back home was diagnosed with brain cancer. Throughout her three years of treatment, May flew back and forth to their home in Munich to be with her and help manage her care. When she developed dark sores on her skin, an oncologist suggested they might be caused by the dye used to color her bed sheets.

“I thought, next this guy is going to bring crystals and moonlight,” May says. “It didn’t make any sense to me.” But he bought organic, light-colored sheets, and her sores went away. “It could have been a coincidence, but I thought, well, what is color made of? Where does it come from?” May did a bit of research, and the answer was: petrochemicals. Almost all dyes, even ones used on certified organic textiles, are made from petrochemicals.

This brain worm—the question of what is in the dyes in textiles and what they do to our bodies—stayed with him after his mother passed away and as he started to work for a German medical device company. Around 2017, he decided he would either let the issue go or follow it down the rabbit hole.

He chose the latter, which led him to founding Aizome. He calls it a health care company that sells bed sheets infused with herbal dyes and absolutely nothing else. May did not set out to launch a twee artisan brand; in fact, there are several brands selling undyed or naturally dyed bed sheets already. Instead, with Aizome, May wants to prove that what we wear and what we sleep in has an impact on our health. And that by using modern technology, we can go back to a time before we were saturated in environmental pollutants.

Person cuddled up in bed with blue sheets
Photograph: Aizome

Bright Colors, Dark Days

Azo dyes, which make up 70 percent of the 9.9 million tons of industrial dye colorants used globally each year, are a controversial topic.

Some are known skin sensitizers—causing rashes and other skin problems—but it’s not the dyes themselves that cause the most serious harm. Manufactured from petroleum and natural gas, many dyes release a basic chemical building block called amines when they come in contact with the bacteria that live naturally on our skin. Many of these amines are suspected to be carcinogenic, mutagenic, and genotoxic, meaning they could cause genetic changes in human cells, along with cancer. The European Union has banned 22 dyes for this reason. But there are thousands of dyes and other chemical products used in fashion that have never been tested at all.

“I see every day, just in our raw data that the instruments produce, that there are often thousands of chemicals in a sample that can’t be matched to a known chemical,” Kirsten Overdahl, who has published research on azobenzene disperse dyes used in children’s apparel, told me in 2022 in an interview unrelated to Aizome. “That’s absolutely terrifying. This doesn’t mean that every chemical is bad. Maybe it’s harmless. But if we can’t match a name to a chemical structure, it means that the data is not out there. So you can’t say it’s not safe, but you also can’t say it is safe.”

Heather Stapleton, an environmental chemist and exposure scientist at Duke University who guided Overdahl’s research, agreed. “When it comes to someone’s health and particularly the health of a child or an infant, I think we need to be more transparent—in particular, chemicals used in products that come in direct contact with our skin and our bodies,” she told me. “If we don’t, it’s going to make it harder to understand what’s contributing to cancer and asthma and all these other diseases that are out there.”

Beyond the mysterious dyes, many other known harmful substances can contaminate textiles. According to the industry group Afirm, heavy metals are sometimes used to cheaply create or brighten certain colors and can show up in the final product that’s on shelves. There can also be pesticides, biocides, formaldehyde-based wrinkle-free finishes, and other finishes and contaminants.

In the US, there’s nothing illegal about selling sheets or other textiles that are saturated in these substances to adults. If you’re selling in California, you need to slap a warning label on your products. But otherwise, shoppers never get a full ingredient list of what is in and on their sheets.

“People who have TSW [topical steroid withdrawal], people with eczema, people who have hypersensitivity to textiles, there’s no product they can choose that can promise them that it’s safe and free of [synthetic] chemicals,” May says.

Indigo Gets a Glow-Up

Strands of white fabric getting dipped into blue dye

A natural indigo dye.

Photograph: sornwut tubtawee/Getty Images

Michel May started spending his evenings downloading and poring through research about the medicinal benefits of plant-based dyes. In 17th-century Japan, samurai wore indigo-dyed undershirts to promote wound healing, and regular people wore indigo-dyed cotton to heal their eczema. In Japan, indigo dying is called aizome. (As evidence of his single-minded focus, May took his now-wife to a natural dye workshop in Japan’s countryside for their first date.)

One problem with natural dyes and indigo in particular is that they can bleed, and people don’t like it when their blue jeans rub off onto their car seats and couches. As May dove deeper into fabric dyeing, he found a stark ideological split between the East and the West. Most of the research on whether plant dyes can be used in colorfast modern clothing is from Asian universities. They witness the terrible pollution from dye factories and dye houses and want to find a solution. But an Italian dye maker told May at a trade show that Western brands won’t pay even a 1 percent markup for safer, healthier dyes. Reason being, there’s no demand for it.

Eventually, May found a Chinese professor at Beijing University who was setting up a pilot factory for plant-dyed fabrics, intending to market it as Chinese medicine. The order minimum was 5,000 meters.

So in 2018, May created crowdfunding campaigns at Indiegogo and Kickstarter to build a business selling natural-dyed bed sheets, figuring as squares of fabric, they’re the simplest product to use up that 5,000 meters. Plus, we spend more time touching our sheets than any other textile product. He got $125,000 in sales within a week from all over the world. (His biggest customer base was in, you guessed it, California.)

Midway through that first hectic year, he quit his day job. By the time he delivered all the sheets, May’s bank account was drained. But emails came in from customers who deeply appreciated the sheets. One wrote to May saying he was dealing with end-stage cancer, and the sheets gave him comfort. Another Indiegogo backer offered May more funding to keep the business going.

Now, Aizome has a team of six people and offers what it calls “plant-made, consciously produced bedding without synthetic chemicals” that the company claims is naturally antibacterial, free of allergens, and friendly to the human microbiome. The organic cotton fabric is infused with herbal dyes using a patented ultrasound process. Then it’s washed only with water—no caustic soda, detergents, or bleach—and treated with bio-enzymes instead of silicone or other synthetic finishes.

Hand holding a vial of liquid with 2 clear containers to the right

Aizome launched a skincare line in 2023 that reuses its own wastewater.

Photograph: Aizome

To prove its point, last year Aizome released a skin-care product called Wastecare created from Aizome’s own industrial wastewater, racking up awards for creative advertising from Cannes Lions International Festival of Creativity, the Webby Awards, and Fast Company. It’s collaborating with a pharmaceutical company in Japan to register its wastewater as an active cosmetic ingredient with the International Nomenclature of Cosmetic Ingredients system so other companies can use it in their products.

The first orders of Aizome’s naturally dyed, medicinal T-shirts—the start of its Healthware line—should ship in July.

Totally Intended to Treat

At first, I wasn’t sure what to make of May. I’ve encountered many overambitious social entrepreneurs who say they’re going to change the world one purse or pair of shoes at a time. May is ambitious, but strategic. He founded Aizome to prove a point: that modern, colorfast, naturally dyed textiles are possible, that they are better for us, and that people will pay more for textiles that are free of harmful chemicals.

When I first talked to May in December 2023, he was in northern Thailand for a two-month working retreat. He had brought Aizome’s six-person team along with him, as well as his wife (Aizome’s cofounder), his newborn, and an environmental lawyer, Karen Wade Cavanagh.

Cavanagh has spent her career working on the legal side of building decontamination efforts after anthrax attacks and natural disasters such as Hurricane Katrina. Her job was about protecting people in public spaces and commercial buildings from hazardous contaminants and harsh chemicals. “We know these chemicals are not safe,” she says, referencing things like formaldehyde. “We don’t expect to be living with them, breathing with them, sleeping with them.”

What she’s saying is that unless you’re truly scrupulous, your home is likely full of poorly regulated consumer products off-gassing noxious volatile organic chemicals, leaching endocrine disruptors like BPA and phthalates, and shedding plastic microfibers infused with hazardous chemicals.

Cavanagh was attracted to Aizome because of the complexity of navigating regulations on health products set by the US Food and Drug Administration. And she wishes something like Aizome had been available when her kids were young. Cavanagh’s now-grown children have suffered from allergies, ulcerative colitis, and asthma so severe they’ve landed in the hospital. One couldn’t stand the feel of clothing tags touching his skin. “I know that my son was always sensitive to what he was wearing. I didn’t understand it, but I knew it was real,” she says. “And yet, people with these problems, they go to the doctor, and they’re either told it’s in their head, which is not helpful, or they’re given medication and are told there’s nothing they can do.”

While most supplements have a disclaimer that they’re not intended to treat, mitigate, or cure any diseases, Aizome sheets are now registered with the FDA as Class 1 medical devices intended to mitigate and alleviate skin problems.

This strategy seems to be working. Aizome is big in the eczema community—it was recommended by the National Eczema Association until last year when, ironically, the NEA scrapped the entire textile category, saying textile products are too complicated to assess.

May has been single-minded about proving his theories. He was one of the authors, along with two Egyptian researchers and a University of Cambridge researcher, of a 2022 study in the Journal of Applied Biomedicine showing indigo’s wound-healing properties. Aizome is opening a research division to use government grants to test the medicinal properties and microbiome effects of dyed fabrics. Research showing indigo’s antibacterial properties has been around for a while (Aizome claims these properties help neutralize body odor).

Even if you think all of this is total bunk, if you have the money to spend, there’s no real downside to slipping into classy pastel cotton sheets for a good night’s sleep, free of the anxiety about what synthetic chemicals could be lurking in them. A calm mind leads to better rest.