You notice it the moment you put on great activewear: the stretch, the support, the confidence before you have even started moving. But increasingly, people are asking a different question — what is actually in the fabric?
Searches for "PFAS in clothing," "PFAS in activewear," and "are PFAS in gym clothes safe" are rising across the UK, as awareness grows around the materials used in everyday wear.
PFAS (per and polyfluoroalkyl substances) are a large group of synthetic chemicals widely used for their ability to repel water, oil and stains. In activewear and performance fabrics, that has often meant durable, easy care finishes that hold their shape and look over time.
But there is a trade off. PFAS are often called "forever chemicals" because they break down very slowly and persist in the environment. As research, regulation and consumer awareness evolve, more people are looking to understand what this means — not just for the environment, but for everyday products worn close to the skin.
In this guide, we will break it down clearly and objectively:
- What PFAS are and why they matter
- Where they show up in clothing and activewear
- What the science actually says about health (without panic or exaggeration)
- Why activewear has been a focus and what is changing
- How to choose PFAS free activewear in the UK
Because at Seissense, the goal is simple: activewear that performs, feels refined, and is designed with intention — starting with what is left out, not just what is added. From day one, Seissense has taken a clear approach: designing products without PFAS. Shop the PFAS Free collection
PFAS in clothing: what they are and why they matter
PFAS stands for per and polyfluoroalkyl substances — a broad group of chemicals, with thousands of individual compounds. They are used because the carbon fluorine bond is extremely stable, which is why they are effective at repelling water and oil and why they are often called "forever chemicals."
The US Environmental Protection Agency (EPA) describes PFAS as widely used, long lasting chemicals that break down very slowly over time, and notes they are found globally in the environment and in people's blood at low levels. The UK Government similarly frames PFAS as a long term, complex chemical challenge because of their persistence and widespread presence.
Why the definition matters (and why "PFAS free" can be confusing)
Because PFAS is a large family, it is easy for messaging to get messy. The OECD has published guidance to reconcile PFAS terminology and definitions, specifically because the universe of PFAS is broad and has expanded significantly over time.
That is why the most trustworthy approach is:
- Clarity on what is excluded (PFAS and fluorinated finishes), and
- Proof through materials and supply chain controls, not vague claims
Where PFAS are found in activewear and textiles
PFAS have been used for decades in clothing and textiles to provide functional properties like water repellence, oil repellence, stain resistance, durability and thermal stability.
The European Environment Agency (EEA) notes that both polymeric and non polymeric PFAS are used in textile products, and that PFAS can be released during a product's lifespan — including when textiles are washed.
"But I am not buying a rain jacket — why would gym clothes contain PFAS?"
Not every legging contains PFAS. But performance fashion can overlap with the same finishing chemistry used in outdoor gear — especially when a brand wants fabric to resist moisture and oils, stains and dirt, and heavy wear and frequent washing.
In other words: PFAS has often been used as a shortcut to a "does it all" finish. The problem is that the "does it all" finish comes with a long tail — for the environment, and potentially for health, depending on the specific PFAS and exposure pathway.
How PFAS can be released from textiles (washing, wear, time)
A peer reviewed study in Environmental Science & Technology investigated PFAS emissions from functional textiles exposed outdoors for six months, followed by abrasion and washing. The researchers reported loss of PFAS containing textile fragments (including microfibres) and the formation and loss of lower molecular weight PFAS during weathering, with additional stressors like washing contributing to changes.
The EEA similarly states that both polymeric and non polymeric PFAS can be released during a textile product's lifespan — including during washing — and identifies textiles as a significant source of PFAS pollution in Europe.
What this means in real life: Even when PFAS are used as finishes rather than free liquids, textiles can still contribute to PFAS entering waste streams and the environment over time.
PFAS health effects: what the science says
1) PFAS health research is active and not all PFAS are equally studied
The UK Health Security Agency (UKHSA) notes that investigating PFAS health implications is an active research area, and highlights limitations and uncertainties because toxicity and epidemiological data are not available for many PFAS. The EPA also emphasises that there are thousands of PFAS, used across many products, which makes assessing risks challenging.
We cannot collapse PFAS into one single, simple health outcome.
2) For some PFAS, human studies show associations with specific outcomes
The ATSDR (CDC) summarises that a large portion of evidence suggests associations between exposure to certain PFAS and outcomes such as increased cholesterol, small decreases in birth weight, lower antibody response to some vaccines in children, and certain cancers for specific PFAS (e.g. PFOA).
UKHSA similarly notes that several health effects are reported to be associated with PFAS, including liver effects, immune impacts, developmental effects, and cancer — while also stressing uncertainties and that human epidemiology for even well studied PFAS can be inconclusive.
3) The key question is exposure — and clothing is one part of a bigger picture
EPA notes PFAS are found in water, air, soil, fish, and widely in the environment. UKHSA also states the main route of PFAS exposure for the UK general population has not yet been determined.
Clothing is not the only factor — but it is also not irrelevant, especially for items worn close to the skin and washed frequently. If there is uncertainty, choosing to reduce avoidable exposures — particularly in everyday products worn against the skin — is a sensible, modern, "designed with intention" decision.
PFAS free activewear UK: what to look for
If you are searching for PFAS free activewear in the UK, you are not alone. The shift is happening for a few reasons.
Policy signals are getting louder
- The UK Government's PFAS Plan describes PFAS as a pressing chemical challenge and explicitly includes textiles among the many applications where PFAS have been widely used.
- In the EU, ECHA has been progressing a restriction proposal under REACH, with updates that include assessments across sectors such as technical textiles.
- California's AB1817 prohibits (from 1 January 2025) manufacturing or selling new textile articles containing regulated PFAS.
If you are looking for PFAS free activewear designed for everyday performance, explore the Seissense collection
Forever chemicals in gym clothes
The term "forever chemicals" is not a marketing invention — it is a reflection of persistence. The UK Government explicitly uses this language in its national PFAS plan. The EPA likewise notes PFAS break down very slowly over time and are widespread globally.
Why gym clothes are a particular focus
Shop PFAS Free Women's Leggings
Activewear tends to be high contact (worn close to skin), high heat (body temperature rises during exercise), high wash (frequent laundering), and high performance (demand for durability, shape retention, stain resistance).
The EEA notes PFAS can be released during a product's life, including washing. Peer reviewed research also shows that weathering, abrasion and washing can contribute to PFAS losses and emissions from functional textiles.
The concern is not just "what is in the fabric," but what that fabric might shed into the environment over time — and how to design out avoidable chemistry in the first place.
Are PFAS essential for gym wear performance?
The EEA briefing is clear: the use of PFAS in most types of textiles is not a technical necessity, and feasible alternatives exist for many non essential uses. Performance does not automatically require PFAS.
PFAS free leggings UK: how to shop smarter
If you are specifically searching for PFAS free leggings in the UK, here is what to look for:
- Look for clear, unambiguous claims — "100% PFAS free," "free from forever chemicals," "PFAS free from the fabric up." Seissense uses this kind of direct language in its product positioning.
Shop PFAS Free Women's Leggings
- Understand why PFAS testing is not always simple — PFAS presence can vary across the life of a garment. The conversation has moved toward upstream elimination and supply chain control, not only end product testing.
- Ask the questions brands should answer — Are PFAS used in fabric finishes? Do you exclude them across the whole range? The brands doing this properly will not dodge.
- Choose designs built to last — Longevity reduces consumption pressure. Seissense's "Designed to last" stance is built into the product, not painted on.
Are my gym clothes toxic?
The honest answer: not automatically — but the concern is valid.
- PFAS exposure science is complex; uncertainty exists for many compounds.
- Associations between certain PFAS and specific health outcomes are reported, but that does not mean every exposure source produces the same risk.
- A garment containing PFAS does not automatically equal "toxic to you" — but it does mean chemistry that regulators and health bodies are actively working to reduce.
A better framing: can you reduce avoidable exposure without sacrificing performance? If you can choose activewear that performs, lasts, feels good on skin, and avoids a class of persistent chemicals used largely for convenience — that is a high quality choice.
Why most activewear still uses PFAS (and why change takes time)
- Legacy supply chains. PFAS chemistry has been embedded in textile finishing for decades.
- Performance shortcuts. Water and oil resistance is easy to sell and PFAS deliver it reliably.
- Mixed regulation globally. Rules differ by region; policy is evolving, but not uniform.
- Complexity of the PFAS family. Definitions and scope matter, hence ongoing OECD work on terminology.
The good news: regulators and agencies increasingly describe the need to transition to safer alternatives, and the EEA explicitly points to feasible alternatives for many textile uses.
The Seissense PFAS free approach: performance without compromise
Seissense started with a no PFAS commitment, built on the belief that performance should not come at the cost of your health or the environment.
Unlike many brands that remove PFAS only in select lines, Seissense takes a whole range approach — designing out PFAS from the fabric stage. Every piece is engineered without fluorinated chemistry, with materials and performance considered from the outset.
What you get when PFAS are designed out
- Confidence against skin (because you know what is not in it)
- Cleaner material intent (less reliance on persistent chemistry for convenience)
- Performance without compromise (because PFAS are not technically necessary for most textiles)
A practical checklist: how to reduce PFAS exposure from clothing
- Prioritise next to skin pieces — Start with what you wear closest and most often: leggings, bras, base layers.
- Choose PFAS free where it is non essential — The EEA indicates PFAS are not technically necessary for many textile applications, with alternatives available.
- Do not over index on one product category — Clothing is one part of a bigger picture: food, water, environment, and products all play a role.
- Buy less, buy better — Choosing long lasting pieces supports lower turnover and aligns with Seissense's "designed to last" philosophy.
A simple takeaway
You do not need to compromise performance to make more intentional material choices. PFAS in clothing is a materials topic, a wellbeing topic, a health research topic, and a policy topic — all at once.
- PFAS are persistent and widespread.
- PFAS have been used in textiles for performance properties and can be released over a product's life, including washing.
- Health evidence shows associations for some PFAS, while uncertainty remains across many compounds and exposure routes.
Seissense approaches activewear differently. Instead of removing PFAS as an afterthought, the range is designed without fluorinated chemistry from the outset — focusing on refined, functional design, comfort against skin, and durability that supports long term wear.
Explore the PFAS Free range
Shop Women's Leggings
Shop Women's Activewear
Shop Men's Activewear
Frequently asked questions
What are PFAS in clothing?
PFAS are a large group of synthetic chemicals used for properties like water and stain resistance; they are persistent and break down very slowly.
Why are PFAS called "forever chemicals"?
Because many PFAS persist in the environment for long periods and degrade very slowly over time.
Are PFAS in clothing harmful?
Health agencies report associations between exposure to certain PFAS and some health outcomes, but research is ongoing and uncertainty exists for many PFAS; risk depends on exposure pathways and specific compounds.
Can PFAS be released from clothes when washing?
Yes. The EEA notes PFAS can be released during a textile's lifespan including washing, and peer reviewed research shows weathering and washing and abrasion can contribute to PFAS losses from functional textiles.
Is PFAS essential for activewear performance?
The EEA states PFAS use in most textiles is not a technical necessity and alternatives exist for many non essential uses.
Do PFAS absorb through skin?
Current evidence suggests ingestion (food and water) is a primary exposure route; research on skin absorption is still evolving and depends on the specific PFAS and exposure conditions.
How do I know if clothing contains PFAS?
PFAS are not usually listed on labels, but water, oil, or stain resistant claims can indicate their use; the clearest sign is a transparent "PFAS free" or "no added PFAS" brand claim.
What does PFAS free mean at Seissense?
Seissense positions its range as PFAS free athleisure designed to perform, and states its best sellers are 100% PFAS free and free from forever chemicals from the fabric up.
Sources: US EPA · ATSDR/CDC · UKHSA · GOV.UK PFAS Plan · EEA · Environmental Science & Technology · OECD · ECHA · California ARB AB1817
