Nike Women's Fastback One Piece Swimsuit
Skip until Nike discloses water-repellent coating chemistry; PFAS risk unclear.
Nike Fastback swimsuits likely use water-repellent coating treatment typical of performance swimwear, but Nike does not disclose whether their formula contains PFAS.
The better-graded swap
Patagonia
Patagonia Women's Bottom Turn Racerback Bikini Top
90/100 safety
Same rubric that flunked this product. The swap earned Excellent.
Still want this one anyway? Check the price on Amazon. We’d swap it.
Material
Nylon/polyester blend with water-repellent coating finish
Lab data
No public lab test
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What Nike Women's Fastback One Piece Swimsuit is made of, ingredients and materials
This swimsuit is constructed from a nylon-polyester blend, a durable synthetic mix common in performance swimwear. The water-repellent coating (water-repellent coating) finish applied to the fabric is the critical unknown, water-repellent coating coatings historically used long-chain PFAS (perfluorooctanoic acid and similar compounds) to repel water and chlorine. Nike has not publicly disclosed whether this specific product uses legacy PFAS-based water-repellent coating, fluorine-free alternatives, or a hybrid formulation. The nylon and polyester themselves are not inherently hazardous at normal use, but the finish chemistry determines skin exposure risk during wear and washing.
What’s concerning
Category baseline
The starting point for this type of product, before anything specific to this product is counted.
No PFAS disclosure
No public statement from the brand about PFAS in this product.
Waterproof / stain-resistant treatment
Water-repellent coating treatments have historically used PFAS.
PFAS
Nike's water-repellent coating formulation for this product is undisclosed. Long-chain and short-chain PFAS remain common in water-repellent textiles despite industry phase-out commitments. Skin contact during wear and potential migration during washing present low-to-moderate chronic exposure, though acute toxicity at normal use is not established.
Source, ATSDR ↗Microplastics
Polyester blends shed microfibers during washing, particularly with mechanical agitation and chlorine exposure. The extent is not product-specific data but is a general concern for synthetic swimwear; air-drying and gentle laundering reduce shedding risk compared to machine washing.
Source, EPA ↗What’s reassuring
Azo dyes and colorants
No recalls or reports of hazardous azo dyes or restricted colorants in Nike swimwear. Standard disperse and reactive dyes used in polyester/nylon are regulated; migration to skin during normal use is minimal. No product-specific concerns documented.
Formaldehyde / VOCs
Nylon and polyester swimwear rarely use formaldehyde-releasing resin finishes (more common in cotton); no known formaldehyde hazard reported for Nike performance swimsuits. Standard industrial testing typically screens for this on branded athletic wear.
Source, ATSDR ↗Elastane (spandex) degradation and leaching
Swimsuits typically contain 15-20% elastane for stretch; no established hazard from elastane itself at normal wear temperatures. Degradation occurs with age and UV/chlorine exposure, affecting fit rather than chemical safety. No toxicological reports specific to Nike products.
How is this PFAS grade calculated?
The brand's record and disclosure
Nike has faced criticism for opacity on PFAS in water-resistant apparel but has made commitments to phase out long-chain PFAS in some product lines by 2025. However, the company does not systematically disclose water-repellent coating chemistry on individual products or at the point of sale. No product-specific certifications (such as GOTS or OEKO-TEX) are advertised for this swimsuit, limiting independent verification. Nike's silence on this product's water-repellent coating formulation mirrors industry-wide reluctance to specify fluorine alternatives, making definitive safety assessment impossible without direct inquiry to the brand.
How it compares in its category
Most mainstream performance swimsuits (Nike, Speedo, Adidas, TYR) use synthetic blends with water-repellent coating finishes and face the same PFAS disclosure gap. Brands offering PFAS-free certified alternatives (e.g., Patagonia Wear Tested line, some Orca models) are rare and typically more expensive. Standard drugstore and fashion swimwear often omit water-repellent coating entirely, reducing PFAS risk but sacrificing durability in chlorine. This Nike product sits in the mid-market performance tier where water-repellent coating is standard but transparency is inconsistent across the category.
If you buy it
Wash in cool water and air-dry to minimize degradation of the water-repellent coating and any potential leaching during hot-water cycles. Avoid chlorine exposure for extended periods if possible, as repeated chlorine contact can break down both the nylon and the water-repellent layer over time. Replace the swimsuit every 1-2 years of regular use or sooner if the fit, seams, or repellent properties noticeably degrade. Before purchase, contact Nike customer service directly to request the specific water-repellent coating chemistry; a clear answer (fluorine-free, legacy PFAS, or hybrid) will inform your confidence in the product.
What is not known about PFAS in this product?
- Basis
- Model estimate, 45% confidence, not a lab result
- Lab test
- None on record for this exact product
- Brand statement
- Nike has made a specific claim
Formulations change between production runs, so check the current label. How we grade.
What are the PFAS-free alternatives to Nike Women's Fastback One Piece Swimsuit?
- Nylon/polyester blend with elastane (standard swimwear)
- The brand calls it PFAS-free, which we have not verified
- Elastane (spandex) degradation under heat or chlorine
- Cotton/cotton-blend seersucker plaid
- We found no PFAS statement from the brand
- Azo dyes and colorfast stability
2 hazards checked on this product, all on its full breakdown.
Find an alternative on Amazon
- Polyester/nylon swimsuit fabric, likely uncoated or standard finish
- Azo dyes and synthetic colorants
4 hazards checked on this product, all on its full breakdown.
Find an alternative on AmazonMore swimwear grades
How we score, every product runs through the same public 0-100 rubric based on materials, coatings, brand disclosure, lab findings, and recalls. See the full methodology → Spotted a mistake? Report an error.