How to verify certification, understand tested substances and limit values, and choose safer swimwear with confidence.
Reviewed by: Textile Chemical Compliance Editor
Editorial role: Internal technical content review (non-OEKO-TEX® body)
Last updated: November 2025
Standards referenced: OEKO-TEX® STANDARD 100 (Limit Values Appendix 4, 2025 edition), REACH Annex XVII, CPSIA, ISO 14184-1
Key Takeaways
Look for the “STANDARD 100 by OEKO-TEX®” label on swimwear. This label indicates the item has been tested for over 100 regulated and non-regulated substances using internationally aligned criteria.
Swimwear typically belongs to Product Class II, which specifies stricter limits for textiles in extensive, direct contact with skin.
STANDARD 100 focuses on human health (chemical safety), not environmental performance. For sustainability and traceability, additional labels such as MADE IN GREEN by OEKO-TEX® are needed.
You can independently verify any certificate number via the official OEKO-TEX® Label Check: https://www.oeko-tex.com/en/label-check.
Certified products help reduce exposure to allergenic dyes, certain heavy metals, formaldehyde, phthalates and selected PFAS, by requiring compliance with conservative limit values.
1. What Is OEKO-TEX® STANDARD 100?
1.1 Certification Overview
OEKO-TEX® STANDARD 100 is a globally recognized label for textiles tested for harmful substances. It can be applied to yarn, fabrics, accessories and finished products such as swimwear. Every component of a certified article—including outer fabric, lining, sewing threads, labels, prints, elastics and even small accessories—must comply with the applicable criteria.
The test catalogue covers regulated substances (legal requirements) and many voluntary parameters. According to OEKO-TEX®, the criteria often go beyond national and international regulations for textile products, and are periodically updated as toxicological and regulatory knowledge advances.
1.2 Substance Groups Covered
STANDARD 100 includes, among others, limit values and requirements for substance groups such as:
Prohibited and restricted azo dyes and carcinogenic dyes
Formaldehyde (free and partially releasable), tested by established methods such as ISO 14184-1
Extractable heavy metals (e.g. lead, cadmium, nickel release, arsenic, mercury)
Pesticides and chlorinated phenols
Phthalates and other plasticisers used in prints and coatings
Selected PFAS and other fluorinated compounds, following stricter detox and MRSL trends
Allergenic disperse dyes and other dye classes with sensitisation concerns
Certain organotin compounds, flame retardants, and other specialized auxiliaries
The detailed list, including analytical methods and limit values, is given in the official OEKO-TEX® STANDARD 100 Limit Values and Individual Substances document (Appendix 4).
2. Safety vs Sustainability
STANDARD 100 is dedicated to human-ecological safety — that is, minimizing harmful substances in contact with your skin. It does not by itself guarantee low environmental impact or ethical production. For that, OEKO-TEX® offers additional schemes such as MADE IN GREEN, which incorporate supply-chain traceability and environmental/social auditing.
Distinction | STANDARD 100 by OEKO-TEX® | MADE IN GREEN by OEKO-TEX® |
|---|---|---|
Main focus | Human-ecological safety (harmful substances) | Environmental performance, social criteria and traceability |
Scope | Tests finished products and components for chemical residues | Assesses production facilities and supply chain transparency in addition to product testing |
Traceability | Not inherently traceable beyond certificate data | Traceable via QR code or ID linking to facility and product information |
Key benefit | Reduced risk of harmful chemical exposure to the wearer | Combination of product safety with sustainability and social compliance |
For skin-safe and more sustainable swimwear, many consumers look for STANDARD 100 plus an additional sustainability certification (such as MADE IN GREEN or EU Ecolabel).
3. Chemical Exposure in Swimwear: What Matters?
3.1 Common Chemicals in Swim Fabrics
Modern swimwear is typically made from synthetic blends such as polyamide (nylon) and elastane (spandex). During dyeing, printing and finishing, a variety of chemical auxiliaries may be used. Residual levels can include:
Disperse dyes and pigments used for bright, saturated colours
Finishing agents that improve colourfastness, handle, or drying time
Water- and stain-repellent treatments, sometimes based on fluorinated chemistry
Plasticisers and binders in prints or logos
At well-controlled, low concentrations these substances are typically safe for the general population. Issues arise where limit values are exceeded or where particularly sensitive individuals (for example, people with atopic dermatitis or specific dye allergies) are exposed.
3.2 Health Considerations (Evidence-Based, Non-Alarmist)
For most people, the primary concerns with non-certified swimwear relate to skin irritation and contact dermatitis. This can be influenced by:
Residual allergenic disperse dyes or finishing agents
Inadequately controlled formaldehyde-based finishes
High levels of certain heavy metals in pigments
Interactions between pool disinfectants (such as chlorine) and the chemicals present in the fabric
STANDARD 100 does not claim to eliminate all possible reactions, especially in individuals with very sensitive skin, but by imposing conservative limit values and excluding certain hazardous substances it substantially reduces the overall risk profile of the textile.
4. Why OEKO-TEX® STANDARD 100 Matters for Swimwear
4.1 Product Classes and Swimwear (Class II)
STANDARD 100 categorises textiles into four product classes, depending on intended use and skin contact. Swimwear normally falls into Product Class II (direct contact with skin).
Product Class | Description | Typical Examples |
|---|---|---|
Class I | Textiles and textile toys for babies and toddlers (0–3 years) | Baby bodysuits, rompers, baby hats, soft toys |
Class II | Textiles with large-area, direct skin contact | Swimwear, underwear, T-shirts, bedding |
Class III | Textiles with little or no direct skin contact | Jackets, coats, lined outerwear |
Class IV | Decoration materials | Curtains, table linens, upholstery fabrics |
The principle is straightforward: the more intensive the skin contact and the more vulnerable the user group, the stricter the corresponding criteria. For swimwear, long durations of direct skin contact and exposure to warm, wet environments make conservative limit values especially relevant.
4.2 Selected Limit Value Examples (as of 2025)
The complete limit value tables are maintained and published by OEKO-TEX®. The examples below illustrate typical limits for Product Class II according to the currently available Appendix 4 (values rounded, simplified and provided for orientation only; always refer to the latest official document for certification work):
Substance / Group | Example Limit for Class II | Notes |
|---|---|---|
Formaldehyde (free & partially releasable) | ≤ 75 mg/kg | Measured by water extraction methods such as ISO 14184-1; lower limits apply to baby products. |
Cadmium (extractable) | Typically ≤ 0.1 mg/kg | Aligned with strict approaches to cadmium in consumer textiles. |
Arsenic (extractable) | Typically ≤ 1.0 mg/kg | Conservative limit relative to general consumer product legislation. |
Prohibited aromatic amines from azo dyes | Not detectable / banned | In line with EU restrictions on azo colourants releasing listed carcinogenic amines. |
Selected phthalates in prints or coatings | ≤ 0.1% for several key phthalates | Comparable to CPSIA and REACH restriction levels for children’s products. |
These values are subject to periodic tightening as regulations and risk assessments evolve. For accurate compliance decisions, always consult the current official OEKO-TEX® limit value document rather than relying on secondary summaries.
5. Verifying Genuine STANDARD 100-Certified Swimwear
5.1 How to Recognize the Label
A genuine STANDARD 100 label typically includes:
The OEKO-TEX® logo and the text “STANDARD 100 by OEKO-TEX®”
A certificate number (for example, “XX 012345 TESTEX”)
The name of the testing institute (e.g. TESTEX, Hohenstein, etc.)
Sometimes a QR code that links to the official OEKO-TEX® entry
Be cautious of labels that contain spelling mistakes, poor print quality or incomplete information (e.g. missing certificate number or institute name), as these may indicate misuse of the label.
5.2 Using the Official Label Check
To verify a swimwear item, you can use the official OEKO-TEX® Label Check tool: https://www.oeko-tex.com/en/label-check.
When you enter the certificate details, you can confirm:
Whether the certificate is currently valid
Which product category and product class it covers
The valid-from and valid-until dates
The manufacturer / brand name and certified articles
5.3 Practical Questions to Ask Brands
If you want extra assurance, you can ask the brand or retailer:
For a copy of the current STANDARD 100 certificate (PDF or screenshot)
Which specific products and components are covered (fabric, lining, trims, prints)
Which product class your swimwear falls into (Class II is typical)
How often they re-certify and whether they also follow additional MRSL/RSL frameworks
6. Choosing Safe, Comfortable and Durable Swimwear
STANDARD 100 addresses the chemical safety aspect, but a high-quality swimsuit also depends on design, material engineering and construction. When comparing certified options, consider:
Factor | Why It Matters |
|---|---|
Material composition | Affects stretch, support, colour intensity and how dyes and finishes interact with skin. |
Chlorine & saltwater resistance | Improves durability and helps prevent fibre degradation that can aggravate skin irritation over time. |
Hydrophobic & quick-dry properties | Help reduce waterlogging and maintain comfort; treatments should also meet chemical safety criteria. |
Construction quality | Flat seams, soft elastics and well-designed linings help prevent mechanical irritation and chafing. |
Fit and coverage | Good fit reduces friction and pressure points, which is especially important for sensitive skin. |
For people with very sensitive skin or a history of textile allergies, choosing STANDARD 100-certified swimwear, avoiding overly intense colours at direct-contact areas, and rinsing garments after each use can further reduce the risk of discomfort.
7. Manufacturing & Compliance Perspective
From a manufacturer’s point of view, achieving STANDARD 100 certification involves more than testing a finished swimsuit once. It requires coordinated work between design, sourcing, chemical management and quality assurance teams.
7.1 Typical Documentation Required
Detailed bill of materials (BOM) listing all fabrics, accessories and prints
Chemical inventory and Safety Data Sheets (SDS) for dyes, auxiliaries and finishing agents
Descriptions of production steps, including dyeing, printing and finishing processes
Representative product samples for laboratory testing
7.2 Testing Methods & References
OEKO-TEX® member institutes rely on a range of standardized test methods. Examples include:
Formaldehyde: water extraction methods such as ISO 14184-1
Heavy metals: ICP-based methods for extractable metals in textiles
Aromatic amines from azo dyes: tests aligned with EU restrictions on azo colourants
Colourfastness and pH: methods drawn from ISO and related textile standards
7.3 Continuous Updating and Annual Renewal
STANDARD 100 is not static. OEKO-TEX® regularly reviews its criteria against evolving regulations such as REACH Annex XVII, national laws, and voluntary MRSLs (for example, ZDHC). Certificates are normally valid for one year, after which renewal and, where appropriate, retesting are required. This system helps ensure that certified swimwear remains aligned with the latest knowledge rather than a one-time snapshot.
8. Frequently Asked Questions (FAQ)
1. What does OEKO-TEX® STANDARD 100 mean for swimwear?
It means the swimwear has been tested against a comprehensive list of harmful substances, using limit values appropriate for Product Class II (direct skin contact). While it cannot guarantee zero risk for every individual, it provides a strong indication that the chemical risk profile of the textile is well controlled.
2. How can I check if a swimsuit is really certified?
Look for the STANDARD 100 label with a certificate number and testing institute. Then use the official Label Check at oeko-tex.com to confirm validity, product class and covered articles.
3. Can certified swimwear still cause skin reactions?
Yes, rarely. Individuals with very sensitive skin, pre-existing dermatitis or specific allergies may still react to certain substances even at low concentrations. However, STANDARD 100 significantly reduces the likelihood of exposure to many known problematic chemicals compared to non-certified products.
4. Is STANDARD 100 the same as eco-friendly or “green”?
No. STANDARD 100 is primarily about chemical safety for the wearer. For environmental and social aspects, additional schemes such as MADE IN GREEN or other sustainability certifications are needed.
9. References & Further Reading
OEKO-TEX® Association. OEKO-TEX® STANDARD 100 — General information and standard overview. Available at: https://www.oeko-tex.com/en/our-standards/oeko-tex-standard-100
OEKO-TEX® Association. Limit Values and Individual Substances according to Appendices 4 and 5 (latest English edition). Available via the OEKO-TEX® website and member institutes.
European Union. Directive 2002/61/EC amending Directive 76/769/EEC regarding restrictions on certain azo colourants in textiles.
Regulation (EC) No 1907/2006 (REACH), Annex XVII — Restrictions on the manufacture, placing on the market and use of certain dangerous substances, mixtures and articles.
ISO. ISO 14184-1: Textiles — Determination of formaldehyde — Part 1: Free and hydrolysed formaldehyde (water extraction method).
U.S. Consumer Product Safety Commission (CPSC). Consumer Product Safety Improvement Act (CPSIA) — Total lead content in children’s products.
OEKO-TEX® / Hohenstein and other member institutes. Public FAQs and technical information on STANDARD 100 product classes and alignment with other RSL/MRSL frameworks.
10. Disclaimer
This article is intended for general informational and educational purposes only. It summarises publicly available information from OEKO-TEX®, regulatory bodies and technical standards at the time of the latest update. It is not an official OEKO-TEX® publication, does not represent legal or regulatory advice, and must not be used as a substitute for the official STANDARD 100 criteria or professional compliance consultation.
Limit values and requirements mentioned here are illustrative and may be simplified. For certification, conformity assessment or regulatory decisions, always refer directly to the current official documents and consult an accredited OEKO-TEX® member institute or qualified regulatory expert.