3 Companies Now Make Biodegradable Polyester. Is It Greenwashing or Real?
We use way too much polyester in our fashion, that is a fact. Nobody needs a polyester sundress, button down, or pajamas. But it’s also a fact that we haven’t yet found a natural, plastic-free way to make a performance sneaker or a lightweight hiking jacket. So even the most outdoorsy climate scientists are currently stuck with at least some synthetic clothing.
One potential solution? Biodegradable synthetic fabrics. There are three different companies who have created a synthetic fiber with an additive that makes it break down in the presence of bacteria. And this raises several important questions:
- Do these materials just break down into micro or nano particles (which are more toxic)?
- Do these materials poison the water or soil with toxic chemicals when they break down?
- What are these special additives, and are they safe?
- Can these biodegradable polyesters truly help solve fashion’s plastic problem?
Yeah, I have some concerns about this. But I dug into the science, interviewed researchers, and had multiple long conversations with these innovators and their scientists to understand what exactly is going on here.
So, can you have your polyester performance gear and biodegrade it too? Let’s find out.
Polyester’s Problem 1: Synthetic Fashion Waste
A 2024 study of American post-consumer waste streams conducted by Fashion For Good found that 28% of post-consumer garments are primarily polyester. And right now, it’s safe to assume that any synthetic textile, when it’s done being used or worn, will end up in the landfill, the incinerator, or in the environment.
Photos and testimonials from Ghana’s beaches and smoking landfills as well as Chile’s Atacama desert have shocked even regular consumers who don’t consider themselves eco shoppers. But how big is this problem? While US figures for textile collection are rather opaque, on average, 62% of the volume of clothing that comes to market each year in six Western European countries ends up in landfills or incinerators, according to a study by Fashion for Good. That includes textiles that are trashed by consumers, and textiles that are landfilled or incinerated by sorting facilities because they are not recyclable or re-wearable. Of the textiles collected from consumers, about 43% are sent to the landfill or incinerator, 2% are recycled, about 5% are resold domestically, and 50% are shipped outside of Europe.
That means the majority of used clothing is landfilled or incinerated in developed countries, or end up in the environment or poorly managed landfills in developing countries.
The fact that it takes likely hundreds of years for synthetic fashion to biodegrade also makes consumers feel guilty about their purchases. (Though perhaps not enough to change their shopping behaviors.)
There are promising technologies emerging to chemically recycle synthetic fabrics. However, when or if these technologies are scaled, there is a good chance recycling facilities will still only take in pre-consumer textiles, a.k.a. off-cuts from factories. These textiles can be sourced efficiently and affordably, and have not yet been mixed up and contaminated with trims, potentially hazardous finishes, and other waste.
In short, there will be no collection of post-consumer synthetic textiles for recycling for the foreseeable future, and used synthetic clothing will continue to end up in landfills and waterways.
Polyester’s Problem 2: Synthetic Microfibers
Synthetic textiles shed microfibers at all times. When washed, synthetic materials release microfibers into the wastewater treatment system and to septic tanks fields. From there, they are either released with “purified” water into waterways, or stay a part of wastewater sludge, which is eventually applied to large farms as fertilizer. A 2024 study of a wastewater treatment plant in Hungary found that while most of the microfibers were cellulosic (disintegrated toilet paper), polyester dominated the synthetic fibers.
Microplastics have been found in our bowels, blood, placentas, lungs, and testes. Scientists are just at the beginning of researching the myriad potential health effects of microplastics on our bodies — from cancer, heart disease, and kidney disease; to Alzheimer’s, chronic bowel disease, and fertility.
But regular folks understand, even without the support of studies, that it’s not good to be ingesting microplastics. Just this year, for example, the Washington Post has published four stories on microplastics: their effects on our health, how we breathe them in, more evidence of microplastics health effects, and how to filter them from your tap water.
When worn or used, synthetic materials also release microfibers into the air or into the home, where they accumulate in house dust. From there, we can then breathe them in or ingest them.
What’s worse, according to Susanne Brander, an associate professor and ecotoxicologist at Oregon State University, micro and nanofibers are more toxic than microplastics that come in other shapes, such as pellets or beads. “That has been shown in a number of studies. If you expose larval fish to a type of plastic, and one of the treatments is in fiber form, and the other treatment is in a pellet or sphere form, the fibers are more toxic. They also have the propensity to get caught up in the gills as well of aquatic organisms, and they’re hard to excrete, hard to remove, at that point.”
Polyester’s Problem 3: Toxic Plastic Fabrics
Some consumers are waking up to the fact that polyester and nylon are types of plastics made from petroleum, and a smaller subset are concerned about the toxicity of plastics and the impact on their health. For example, the most popular article on EcoCult by far is a shopping guide to “plastic-free activewear.”
A 2024 flagship report from Europe estimated that there are 16,000 chemicals used in plastics. An estimated 4,200 of them are “of concern” because they are persistent, bioaccumulative, mobile, and/or toxic, while over 10,000 of them entirely lack safety information. Polyester-spandex blends from large brands have been tested by the advocacy organization Center for Environmental Health have been found to have high levels of BPA.
Bioplastics do not have a good history when it comes to toxicity. A 2023 study based on lab experiments, for example, found that the chemicals in compostable plastic bags were more toxic to living cells than virgin and recycled plastics. A 2023 study found that compost containing biodegradable food packaging contained PFAS levels up to 20 times higher than compost from manure, food waste and yard waste.
To my knowledge, there has been no independent research into the toxicity of any of these biodegradable polyesters, just testing commissioned by the innovators themselves. Researchers prefer to study and test materials for toxicity when there is transparency on what exactly is in them. That’s why research so far has focused on PLA packaging and foodware, the most widespread bioplastic. “It’s not possible for us to do assessments of hazard or potential harm without knowing what’s even in the materials,” says Bethanie Almroth, a professor of ecotoxicology and environmental science at the University of Gothenburg, Sweden.
The three researchers I spoke to laid out questions and concerns that come up when considering the toxicity of biodegradable synthetics:
- Are they safe to manufacture, for workers and for communities surrounding the factory?
- Are these materials themselves a non-toxic product?
- Are they free from harmful substances?
- Are they non-toxic to humans, soil organisms, and marine life?
- Are products made with these materials non-toxic?
Problem 4: Biodegradable Plastics That Don’t Biodegrade
According to a recent report by Beyond Plastics, many plastics marketed as biodegradable and compostable are not. A 2019 study found that “biodegradable” plastic bags were still fully intact three years after being buried. Plastics marketed as “compostable” must be sent to a commercial compost facility, many of which don’t accept these products because of the risk of microplastic contamination.
The researchers I spoke to are concerned that quicker breakdown leads to more micro and nanoplastics, which are more toxic than larger plastics. “They’re small enough to cross the epithelial lining of the gut. They’re small enough to get into the bloodstream, if they’re inhaled, and get in through the gills, for example, or on a terrestrial animal, through the lungs,” Brander says. “If an animal might only live for a couple of years, having something break down in five years exceeds the lifespan of that animal. And so it’s still going to be exposed to all of the breakdown products.”
It’s for that reason that oxo-degradable plastics — plastics with additives designed to break them down in open environments, landfills, industrial composting facilities, and water — have been banned in Europe starting in 2019.
It’s also illegal in California, Maryland and Washington to use the term ‘biodegradable’ in marketing claims related to plastic products. AB 1201 in California requires that compostable products meet ASTM standards and be certified by third-party organizations like BPI. The bill also prohibited the use of misleading terms like “biodegradable,” “degradable,” and “decomposable” on plastic products.
But none of the materials in this guide — CiCLO, PrimaLoft, Celys — are oxo-degradable or UV degradable, which is where plastic breaks apart into smaller pieces. They’re all based on hydrolytic biodegradability, which is where, in moist environments, microbes munch on the plastic and turn it into oxygen, methane, CO2, and humus. It’s the most complete form of biodegradation. So I’m tentatively saying that incomplete biodegradation into fragments is not a concern for these material innovations. I could be wrong.
So, now that we’ve outlined all the problems with synthetic fabrics, let’s see if these innovations can solve them.
Intrinsic Textiles Group was spun out of a uniforms and branded merchandise agency in Silicon Valley that served technology and food service clients. In trying to solve its own problem, the merchandise agency ended up inventing the technology behind CiCLO. (There’s no photo for this one because it’s currently going through a rebrand that will not debut until next year, the press representative tells me.)
CiCLO is meant to address the problem of synthetic fibers and microfibers ending up in the landfill or in the environment by helping them biodegrade within a few years, depending on the conditions.
CiCLO chemistry combines a carrier polyester resin and a proprietary chemical mixture. That resin mixture is incorporated into a melted synthetic textile material (polyester or nylon) at the factory. It’s added at around a 2% rate, before the material is extruded through spinnerets to be formed into threads and fabric. The final synthetic textile has “biodegradable spots” throughout that attract bacteria that purportedly break it down completely, leaving behind no microplastics.
Founder Andrea Ferris stressed that the plastic doesn’t disintegrate but is broken down by microbial activity, leaving behind carbon dioxide, water, and microbial biomass (dead bacteria or nutrient rich dirt).
“Our perspective is that biodegradation can be beneficial when used for applications where plastics are unavoidably leaking into the environment and cannot be recovered,” Founder Andrea Ferris wrote via email. “Such is the case with synthetic microfibers shedding from necessary, durable textiles. CiCLO is a specialized solution for the sector of synthetic textiles to reduce unavoidable pollution, and not to be considered a silver bullet solution to plastic pollution of all types.”
To be clear, CiCLO does not claim compostability, either in a backyard or commercial compost facility. Ferris tried to set her company apart from “bad actors doing things like having a very specific fiber, or fibers, certified compostable, then marketing a ‘biodegradable’ yarn for textiles.” (That may be a reference to another innovator, below.)
It claims accelerated biodegradability in a variety of natural and landfill environments where clothing might be sent on purpose or end up accidentally. “We promote CiCLO to brands as one solution to this complex problem of synthetic microfiber pollution and it should be deployed alongside other actions. Source reduction of synthetics, redesigning to shed less, and improving filtration are first lines of defense,” Ferris wrote.
CiCLO synthetics are as durable as regular synthetics. “They can be loved for a really long time, which is why we’re using synthetics in the first place, right?” Ferris says.
Ferris claims that CiCLO has been subject to 10 years of testing, with well over 100 samples — including fibers, yarns, finished fabrics that have been dyed and treated — in third party lab studies by Intertek and Bureau Veritas using ASTM and ISO test methods, compared against the exact same materials without the CiCLO additive.
The simulated environments include biologically active landfills, wastewater treatment plant sludge, natural soil, and seawater, aerobic, anaerobic, and a range of temperatures of up to 125 degrees Fahrenheit to simulate landfill conditions.
CiCLO synthetics can biodegrade anywhere they are exposed to moisture and microbes over an extended period of time. Like all natural materials, CiCLO synthetics will biodegrade the fastest in hot, moist, aerobic environments, and will biodegrade slowest in cold, dry environments. CiCLO has not been tested for biodegradation in commercial composting facilities “because industrial composters actually do not take textiles, nor do I think that they will,” Ferris says.
Not only the polyester or nylon will degrade — any carbon-based chemicals in or on the fabric, including certain dyes, can be broken down by microbes. (Note that dyes can have non-organic chemicals, such as arsenic, in them.)
Ferris is careful to not use exact numbers for speed of biodegradation. “We don’t know exactly where it’s going to wind up. We don’t know or control these environmental conditions, which are truly endless. But what we do know and can confidently confirm is that it’s like incredibly accelerated rates of biodegradation, so it doesn’t persist.”
Ferris claims that CiCLO synthetics biodegrade at a similar rate to wool, and CiCLO has published its test results:
Degradation in Seawater: ≈90% in ≈700 days
Degradation in Soil: ≈75% in ≈300 days
Anaerobic Digester Conditions (simulating landfill): ≈75% in ≈500 days
So, depending on the conditions, we can expect CiCLO synthetic fibers to mostly biodegrade between one and two years. Ferris says that they “fully biodegrade in 3-4 years.”
Is CiCLO Entirely Non-Toxic?
Because CiCLO’s formulation is proprietary, there are some things we cannot know for sure, except based on what the company tells us and what third-party tests show, which are commissioned and reported by CiCLO. However, patents assigned to Intrinsic Advanced Textiles Inc. indicate the active ingredient is calcium carbonate.
CiCLO is manufactured in North Carolina by Parkdale Mills. Calcium carbonate has clear OSHA restrictions on exposure, leading me to conclude manufacturing safety is not a concern.
Five products by CiCLO are certified by Oeko-Tex ECO Passport. Oeko-Tex ECO Passport is meant as a B2B certification to assure suppliers who want to source safe chemistry products for their certified factories.
CiCLO products are certified at ZDHC Level 1, the most basic level. It means the chemicals in CiCLO were screened using their CAS identification numbers against Oeko-Tex’s list of 2,500 chemicals of concern. CiCLO also completed a self-assessment to verify working conditions and environmental management.
According to Ferris, non-carbon-based substances in synthetic fibers, such as antimony, will not biodegrade. That means they will be present in the final biodegraded product. This category would also include PFAS, which is a persistent, highly toxic class of chemicals. It’s important that a brand using CiCLO work with suppliers that are reputable and certified by bluesign, ZDHC, or Oeko-Tex, for assurance that the fiber containing CiCLO doesn’t have any persistent hazardous substances.
One product, CiCLO 102 for Polyester, has a restriction for heavy metal content, related to the presence of antimony in the polyester carrier. But CiCLO comes in an antimony-free version.
Ferris claims that the products from biodegraded CiCLO have also been tested for toxicity to marine and plant life. “Adding CiCLO to synthetics does not add any additional risk. We have done testing on our chemistry technology itself, and also leftover seawater and soil from long term biodegradation samples.” She added later by email, “Non-toxicity studies have been conducted by Coastal Bioanalysts and Eden Research Lab using bioluminescent bacteria, mysid shrimp, and bean, corn and wheat plants.”
“That substance [calcium carbonate] is not likely to increase the toxicity of the fiber,” agrees Mike Belliveau, founder and former president of Defend Our Health, now founder of Bend the Curve.
Brands That Have Used CiCLO
There was a spate of CiCLO launches by brands in 2022, starting with Billabong. What is concerning is that most of the early adopters are brands that exist as licensed names by financial groups — Nautica, Aeropostale, Lucky Brand, Lane Bryant, Oakley, Champion, and Landau Scrubs — and have very few sustainability efforts, if any. Almost all are American brands, save for one British brand, and most of the products are either gone or on clearance. There are two brands that have sustainability as a core part of their identity who have launched CiCLO products: Girlfriend Collective and Finisterre. Neither still carries them.
The idea for PrimaLoft Bio was born in 2014 when a PrimaLoft product manager said during a weekly research and development meeting, “Why can’t we just make a jacket insulation that we can bury in the backyard?”
PrimaLoft takes water bottles, mechanically recycles them into PET, and adds in a proprietary recipe of additives to make it appetizing to microbes in the landfill, wastewater, and ocean. It then forms that biodegradable PET into insulating fill for puffy coats.
The patent indicates that the additives “may comprise at least one of an aliphatic-aromatic ester (some sort of polymer/plastic), a polylactide, an organoleptic, a monosaccharide, an aldohexose or a combination thereof.” So, some combination of polymers/plastics, sugars, and something that tastes or smells good to bacteria. Cassava says that they didn’t invent a new chemical compound, but created a recipe out of known chemical compounds PrimaLoft already uses in its manufacturing.
The product debuted in 2018. “We consider it a holistic solution for every step of a product’s continued journey,” says PrimaLoft CEO Anne Cavassa. If PrimaLoft Bio fibers end up in the landfill, wastewater, or ocean, they turn into water, CO2, methane, and humus.
So how biodegradable is it? In ASTM D5511 conditions (accelerated landfill environment) PrimaLoft Bio fibers reach 93.8% biodegradation in 646 days. In ASTM D6691 conditions (accelerated marine/ocean environment) it reaches 76.6% biodegradation in 973 days, and in ASTM D5210 conditions (wastewater environment) it reaches 17.8% biodegradation in 241 days.
PrimaLoft testing, using pyrolysis mass spectrometry (PYMS) analysis, found no compounds, fragments, monomers or additives consistent with PET in the biodegraded product. That is, there are no micro or nano particles left behind.
Wait, so how is it possible that there is no microplastics left behind if it’s only 94% biodegraded? Shawn Flavin, Vice President, Advanced Concepts & Innovation at PrimaLoft, explained that the ASTM tests put a sample of the PrimaLoft Bio, inoculum (bacteria), and soil together in a certain biodegradable environments, then measures the methane and C02 off-gassing. They then deduct that from the PrimaLoft mass to deduce how much has been biodegraded. “They basically do the mass balance calculation of the methane and the CO2 from the chemical components in the original structure. It’s not an equal balance based on the chemical structures, meaning there is some carbon that’s left over,” he says.
Is PrimaLoft Bio Entirely Non-Toxic?
While Primaloft is based in New York State, the manufacturing is done globally in Primaloft facilities in Asia, Europe, and North America, and it’s certified as non-toxic by Oeko-Tex and bluesign.
Primaloft does not use antimony as a catalyst, and because right now it’s used for insulation, there are no dyes added. So these are not concerns when it comes to hazardous substances left behind after biodegradation. Flavin adds that the ASTM 1963 tests exposed plants to biodegraded Primaloft Bio and saw no inhibition to plant growth.
Primaloft insulation is not currently in a takeback program, but Cavassa says if it were collected and separated from the jacket, it could be recycled into new insulation. In 2019, third party testing proved it could be chemically recycled.
Primaloft Bio is currently more expensive than regular Primaloft insulation, but Cavassa says that they plan on scaling production. “We’re thinking it will be no additional cost to our brand partners as we start to roll it out across our other products,” she says.
Brands That Have Used PrimaLoft Bio
In Sept 2020, PrimaLoft announced it was launching the Bio line over a dozen European outdoor brands including Icebug, Jack Wolfskin, Maloja, Namuk, and Norrøna, and said the bigger brands Helly Hansen, Houdini, Montane and Rossignol would follow with their own styles in upcoming seasons.
However, the list of brands currently using PrimaLoft Bio is rather short: Ecco Shoes, Maloja, Reusch, Namuk, Aether, and Everlane.
The company that makes CELYS was founded in 2014 in Sydney, Australia by a group of scientists, but didn’t launch its product until early 2024.
CELYS is a biodegradable polyester by Intimiti, a company based between Sydney and Shanghai. Through its partnership with polyester manufacturers in China, it inserts a chemical in the PET manufacturing process to create “hydrolysable linkages in the polymer backbones, thus greatly accelerating the whole biodegradation rate.” In other words, the polyester breaks down more quickly in the presence of water than regular polyester.
CELYS polyester has a different feel and touch from regular polyester, with low-temperature dying, and a soft, cotton-like touch. It is manufactured in short-staple form, like cotton, and then can be used to make a 100% CELYS garment, or blended with cotton, modal, lyocell, or wool. It’s best for knit and woven fabrics, like for t-shirts and hoodies. The downside is that it is not as durable or strong as regular polyester — it’s closer to cotton.
It also claims natural moisture management that stems from its ability to absorb water (unlike hydrophobic regular polyester) and channels that wick moisture away from the skin. Right now, you can only get sweat-wicking with polyester or merino wool. So perhaps the best use case for this fiber is in biodegradable, sweat-wicking sportswear with the soft feel of cotton.
One major difference in CELYS from CiCLO and PrimaLoft Bio is the conditions it biodegrades under: industrial composting. CELYS claims complete microbial decomposition — 95.4% decomposition in 179 days under industrial composting conditions — leaving nothing but biomass, carbon dioxide and water.
CELYS seems to compare itself to CiCLO on this page, saying that while a competitor’s “additive based ‘biodegradable’ polyester” is “partially biodegradable” with “very slow biodegradation” CELYS’s biodegradability is intrinsic to the polyester, and is “complete (>90%) within 180 days.”
In 2023, ANTA Sports, a Chinese brand, launched a compostable sweatshirt made with CELYS polyester. The t-shirt was sent to TUV Rheinland lab in China, where it was placed in a compost bin. CELYS claims within a few months, the t-shirt “had completely disappeared!”
It has the BPI certification indicating third-party verification of compostability for consumers, end-users, and composters. “In the textile industry, CELYS fiber is the only one that has been certified by both DIN CERTCO and BPI to be biodegradable while holds [sic] the same or even superior physical properties of the ordinary PET,” it says on its website.
But, the company warns brands to only use the BPI mark if the entire final product is certified compostable. So, if you had a synthetic label, printing, or polyester stitching, for example, your product can’t be sent to a composting facility.
Well, actually, composting facilities, especially in the United States, won’t accept textiles as of right now. But, Weng says, that’s okay, because the certification’s value is in communicating the biodegradability of the fiber. “Once you are certified even for industrial compostability, it naturally means that it’s fully biodegradable. And also it means that it will generate less accumulation of the micro plastics in the environment, whether it’s in the compost or in the soil.”
“I believe we will have a lot of products for different industries, even bottles, films, packaging materials. Everything made out of this polyester polymer will be biodegradable naturally,” says Weng.
Is CELYS Entirely Non-Toxic?
I was unable to find out through searching patents what that third chemical ingredient might be, but Helen Weng, Global Sales Director, says it’s an easily available chemical already on the market. CELYS has Oeko-Tex 100 certification for chemical safety, and passed the TUV Rheinland test for earthworm and plant toxicity. But without knowing the additive, it’s hard to say with certainty it’s safe.
CELYS is manufactured with partner facilities in China, but Weng and the press representative would not share with me what safety or chemical certifications these manufacturers might have, citing confidentiality. However, this technology can be dropped into any polyester manufacturing facility anywhere in the world. Still, the fact that the entire company seems to operate in China does give me some pause.
It can be dyed with plant dyes, and without disperse dyes, the type of skin-sensitizing dyes that are used on regular synthetics.
Will These Innovations Solve Polyester’s Problems?
And it might be hard to market these materials to consumers. Regular folks can’t compost these textiles in their backyard, and they can’t send them to a composting facility either. So their interactions with these textiles will feel exactly the same: wear it, then donate it or trash it.
At least with CELYS, sensitive consumers wouldn’t have a health reaction the way they do with regular synthetics that have disperse dye. And consumers never touch or even see PrimaLoft Bio because it’s inside items. But anyone who is sensitive to polyester would still react to CiCLO polyester on their skin.
Perhaps that’s why after an initial flurry of product launches from CiCLO and PrimaLoft Bio, large brands haven’t incorporated these innovations into their general product line. It’s just a hard sell.
It’s also worth pointing out that a microbial-based breakdown of microfibers, while reducing the number of microfibers in soil and water, will not address microfibers that we breathe in or ingest from the air or dry indoor environments, nor will it address fashion waste in desert environments.
If all synthetic fabrics were made biodegradable, but everything else stayed the same, we would still be exposed to substances such as endocrine disruptors and heavy metals that may leach out of microfibers when they are in our bodies, or substances that are in the fiber that don’t biodegrade, including antimony and PFAS. But if fashion brands are also forced to clean up their textiles, these biodegradable fabrics would not contribute to the toxic load in our bodies or the environment.
There is a world I could imagine in which, if every synthetic textile was biodegradable, there would be a noticeable and beneficial reduction in the amount of synthetic materials and microfibers in the environment and landfill. So while I can make the case for legislation mandating biodegradability, the business case is much less clear.
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