Swimwear is a category where fabric and finish choices matter more than most. You’re wearing it against skin, often for hours, in environments that can accelerate chemical migration — chlorine, saltwater, and UV exposure all affect how finishes interact with skin and break down over time.
Why Swimwear Often Uses Synthetic Materials
Swimwear has almost universally been made from synthetic fabrics — primarily nylon and polyester with added spandex — because synthetic fibers handle water exposure better than most natural ones. Cotton absorbs water and becomes heavy and slow to dry; silk is too delicate for repeated exposure to chlorine or salt. Nylon and polyester resist water absorption, dry quickly, hold their shape under stretch, and maintain color despite chlorine exposure.
The functional case for synthetics in swimwear is strong. The question is whether those synthetics carry unnecessary chemical treatments, and whether certified or lower-concern options are available.
What Makes Swimwear “Non-Toxic”
“Non-toxic” in swimwear context covers three main concerns:
Dye chemistry: Swimwear dyes must withstand chlorine and UV degradation. Some dye processes use chemical classes with more concern than others. OEKO-TEX® STANDARD 100 certification tests the finished swimwear for restricted substances including certain dyes.
PFAS and quick-dry finishes: Some swimwear and rash guards carry chemical finishes for quick-dry performance or water repellency. Traditional versions of these can involve PFAS. See the section below.
Fiber certification: The underlying nylon or polyester fabric may carry bluesign® or OEKO-TEX® certification, indicating a restricted substances standard was applied during production.
No swimwear fabric eliminates all concerns — even well-certified synthetics shed microplastics. But certification meaningfully narrows the field of chemical unknowns.
PFAS and Quick-Dry Finishes to Watch For
Swimwear doesn’t typically carry the same PFAS-laden DWR coatings as rain jackets, but some categories are higher concern:
Rash guards and surf shirts: Often marketed with “quick-dry” performance claims. Some of these carry chemical quick-dry finishes that may involve PFAS. Look for explicit PFAS-free language or bluesign® certification.
UPF cover-ups and beach layers: Items that market both water resistance and UV protection sometimes carry multiple performance treatments. Check the product page for finish disclosures.
Kids’ swimwear with stain resistance: Some children’s swimwear markets stain-resistant properties — the most likely PFAS signal in swimwear categories. Look for PFAS-free or OEKO-TEX® certified.
Swimwear with built-in sun protection: UPF ratings come from fabric construction (tight weave, dark color, certain fibers), not chemical treatments. A UPF claim alone doesn’t signal PFAS — only when combined with water-resistance or stain-resistance claims does the chemical question arise.
Fabrics to Prioritize
Recycled nylon (ECONYL® and similar): Made from recovered fishing nets and ocean plastic, recycled nylon has the same performance profile as virgin nylon — chlorine-resistant, quick-drying, durable — with a lower input impact. Look for OEKO-TEX® or bluesign® certification alongside the recycled claim.
Recycled polyester: Similar story to recycled nylon. Lower input impact, same performance, same microplastic shedding behavior. Certification matters.
OEKO-TEX® certified nylon or polyester: Certification doesn’t change the fiber’s performance, but it confirms restricted substances were applied during production. A meaningful signal for swimwear.
Hemp blend swimwear: A small but growing category. Hemp is a durable natural fiber that handles moisture reasonably well. Hemp/spandex blends are emerging in swimwear. Lower chemical concern; not yet as widely available as synthetic options.
Organic cotton for cover-ups and beach layers: For beach cover-ups and layers not designed for submersion, GOTS-certified organic cotton is a solid choice. It absorbs water, but for cover-ups that dry in the sun, that’s not a problem.
Tencel®/Lyocell beach layers: For beach cover-ups and swim-to-street pieces, Tencel® blends are soft, lightweight, and lower in chemical concern than conventional synthetics.
Certifications That Matter
OEKO-TEX® STANDARD 100: Tests the finished swimwear garment against a restricted substances list. This is the most practical certification to look for in swimwear because it applies to the final product.
bluesign®: A process-based certification applied to fabric mills. Swimwear carrying bluesign® certified fabric has been produced under a restricted substances manufacturing standard.
GRS (Global Recycled Standard): Verifies the recycled content claim in recycled nylon or polyester swimwear. Doesn’t address chemical safety directly, but confirms the recycled-material sourcing claim is legitimate.
GOTS: Less common in swimwear (most swimwear is synthetic), but relevant for organic cotton cover-ups and beach layers.
How to Use Wove While Shopping for Swimwear
When you’re evaluating swimwear, Wove grades the item on its fiber content and chemical concern indicators. For swimwear specifically:
- Check the fiber content label or product description
- Scan in Wove for an instant grade on fiber type and shedding risk
- Note any performance finish claims on the product page (quick-dry, stain-resistant, water-repellent)
- Look for OEKO-TEX® or bluesign® certification — these are what close the gap between fiber content and full chemical picture
- For kids’ swimwear, apply extra scrutiny to any stain-resistant claims
FAQ
Is all nylon swimwear PFAS-free?
Not inherently — but most plain nylon swimwear without additional performance treatments is lower concern. PFAS enter the picture primarily through added coatings (stain-resistant, water-repellent). Certified nylon without these additional claims is generally lower concern.
Is ECONYL® better than regular nylon for swimwear?
ECONYL® is recycled nylon from recovered ocean waste, which addresses the input side. It performs identically to virgin nylon and sheds the same microplastics. The environmental benefit is in sourcing; the performance and safety profile are the same.
Should I wash swimwear before wearing it for the first time?
Yes — a cold rinse before first wear helps remove surface finish residue and loose dye. This is good practice for all new clothing but especially for swimwear that will be worn against skin in warm conditions.
What about the chlorine-resistant claim on swimwear?
Chlorine resistance is a durability claim, not a chemical treatment. It typically refers to the fiber’s inherent resistance to chlorine degradation (nylon and certain polyesters are more chlorine-resistant than others). It doesn’t imply additional chemical finishes.
Related reading: PFAS in Clothing: What It Is and How to Avoid It · How to Read Clothing Labels
Scan swimwear with Wove before you buy. Download Wove and get an instant grade on any swimwear item’s fiber content and chemical concerns.
Sources
- OEKO-TEX®: STANDARD 100 Certification for Swimwear
- Bluesign Technologies: Approved Substances List
- Global Recycled Standard: Certification Overview
- Environmental Working Group: PFAS in Consumer Products