COS Review, Is COS Non-Toxic?
COS averages 59 out of 100 on PFAS Authority's PFAS and toxin screen across the 8 COS products graded as of October 2026, and none of them reach its 70 point pass mark.
COS grades Good on our four-band scale. On disclosure, the brand says nothing publicly about PFAS. See what every brand has published about PFAS for how that compares.
PFAS Authority is a scoring system, not a laboratory. We do not test products ourselves. Grades are model-based, built from published ingredients, materials, certifications, brand disclosures and third-party lab results where they exist. See the rubric.
Does COS have PFAS, by category
Graded and flagged Poor and Bad, we’d swap these
COS
Bonded-Scuba V-Neck Swimsuit
- Nylon/polyamide blend (bonded construction)
- We found no PFAS statement from the brand
- Azo dyes and colorant residues, Swimwear dyes may include azo compounds (linked to skin sensitivity in rare…
4 hazards checked on this product. See all of them.
COS
Women's Asymmetric Double-Faced Swimsuit
- Polyamide (nylon) blend; double-faced woven textile
- We found no PFAS statement from the brand
- Azo dyes and colorant chemistry, Polyamide swimwear is typically dyed with reactive or disperse dyes, some of…
3 hazards checked on this product. See all of them.
COS
Women's Bonded-Scuba V-Neck Bikini Top
- Nylon/polyamide blend (bonded-scuba knit)
- We found no PFAS statement from the brand
- Azo dyes, COS nylon swimwear may use azo dye colorants; while bluesign-certified facilities restrict…
4 hazards checked on this product. See all of them.
COS
Women's Bonded-Scuba V-Neck Swimsuit in Red
- Bonded scuba neoprene/polyester blend
- We found no PFAS statement from the brand
- Azo dyes in polyester backing, Red polyester swimsuit backing may contain azo dyes; while restricted in EU…
3 hazards checked on this product. See all of them.
COS
Women's Bonded Swimsuit in Brown
- Nylon/polyester blend with elastane (bonded swimwear construction)
- We found no PFAS statement from the brand
- Adhesive/bonding layer leachates, Bonded swimwear adhesives may contain residual solvents or plasticizers; no…
3 hazards checked on this product. See all of them.
COS
Women's Contrast-Trim Swimsuit
- nylon/elastane blend swimsuit fabric
- We found no PFAS statement from the brand
- Microplastic shedding during use and laundering, Elastane-blended swimwear sheds microfibers, particularly…
COS
Scuba Swimsuit
- polyamide (nylon) or polyester blend
- We found no PFAS statement from the brand
- Azo dyes in synthetic textiles, Polyamide and polyester both commonly accept azo-based reactive dyes during…
3 hazards checked on this product. See all of them.
COS
Women's Bonded-Scuba V-Neck Swimsuit
- Polyester scuba-knit bonded fabric with likely water-repellent coating finishing
- We found no PFAS statement from the brand
- PFAS, Standard for bonded scuba-knit swimwear unless explicitly marketed otherwise. COS has not disclosed…
5 hazards checked on this product. See all of them.
What to buy instead Good or better, in the categories COS sells
Patagonia
Women's Bottom Turn Racerback Bikini Top
- 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
COS and PFAS, common questions
- Does COS have PFAS?
- COS averages 59 out of 100 on PFAS Authority's PFAS and toxin screen across the 8 COS products graded as of October 2026, and none of them reach its 70 point pass mark. Grades are model-based estimates built from published materials, ingredients and disclosures, not lab tests.
- Is COS non-toxic?
- No COS product we graded reaches Good. The best of them is Bonded-Scuba V-Neck Swimsuit at 65/100.
- Which COS products should I avoid?
- The lowest-graded COS products we have scored are COS Women's Bonded-Scuba V-Neck Swimsuit, Scuba Swimsuit, COS Women's Contrast-Trim Swimsuit. Each one links to the evidence behind its grade.
Every grade uses the same public rubric. How grades work →