The Standards Map: GRS, RCS, OEKO-TEX, bluesign, ZDHC
Every sustainability label answers a different question; you cannot read a claim until you know what each one actually certifies.
Most "sustainable" labels in textiles look interchangeable but measure entirely different things. Some verify whether a material is recycled, some test that a finished fabric is free of substances harmful to human health, and some audit a factory's chemical inputs or working conditions. A sound sourcing decision starts by identifying which question a given label answers.
Two core axes: product or process
The most robust mental model places standards on two axes. The first is product-based verification: the content of a fabric (recycled share) or its output (residual chemicals) is tested. The second is process-based verification: the chemicals entering a facility, the water and energy consumed, and the social conditions are audited. Some standards such as GRS cover both axes, while RCS covers only content and ZDHC only input chemistry. What matters is not whether a standard is "better" but what its scope actually is.
GRS and RCS: two members of one family
Both are administered by Textile Exchange and verify recycled content through third-party chain of custody; they differ in scope. RCS (Recycled Claim Standard) is a single-attribute standard: it tracks only recycled content and its trace through the supply chain, with no social, environmental, or chemical criteria. RCS applies from a minimum of 5% recycled material; a "Recycled 100" label means 95-100% content, while "Recycled Blended" means 5-95%.
GRS (Global Recycled Standard) layers three more requirements on top of RCS: social responsibility (worker rights), environmental management (water, energy, waste), and chemical restrictions. GRS requires at least 20% recycled content for business-to-business use; to apply a consumer-facing "GRS certified" label on a product, that threshold rises to at least 50%. So "GRS" tells you a fabric is both recycled and made under responsible conditions; "RCS" tells you only the recycled share.
OEKO-TEX: one name, three different certificates
OEKO-TEX is a family rather than a single certificate, and these three are the most commonly confused. STANDARD 100 is a product certificate verifying that the finished item (every component, including yarn, fabric, and buttons) stays within limit values for harmful substances; it sorts products into four use classes. STeP (Sustainable Textile & Leather Production) audits the facility, not the product: chemical management, environmental performance, occupational health and safety, and social conditions. MADE IN GREEN requires both and is a traceable consumer label, guaranteeing a product was tested to STANDARD 100 and made in a STeP-certified facility.
STANDARD 100 classes tighten with the duration of skin contact. Class I (babies and children under 3) is strictest; for example, the typical limit for free/partially releasable formaldehyde is ≤20 mg/kg, while Class II for direct skin contact is looser (roughly ≤75 mg/kg). Class III covers garments with limited skin contact and Class IV covers decoration textiles. The full list of limit values is updated with each in-force edition of the standard; the same fabric must be certified in a different class depending on its end use.
bluesign and ZDHC: stopping chemistry at the source
The bluesign and ZDHC approach focuses on managing chemicals before they enter the supply chain rather than hunting for residue in the finished product — this is called input stream management. bluesign covers the entire supply chain and lists pre-assessed, approved chemical products in a public database (the bluesign FINDER, or bluefinder), while keeping banned substances in its system lists (BSSL, BSBL, RSL) under the precautionary principle. A manufacturer can therefore check whether a given chemical is approved or banned before using it. ZDHC is a collaborative initiative rather than an organization, and its core tool is the MRSL (Manufacturing Restricted Substances List) — a list of chemicals banned from intentional use inside a facility.
The distinction between MRSL and RSL (Restricted Substances List) is critical: an RSL sets allowable residue limits in the finished product (output-focused), whereas the MRSL restricts the chemical itself that may be used in manufacturing (input-focused). ZDHC assigns chemical formulations three conformance levels: Level 1 document review and analytical testing, Level 2 an on-site assessment of management systems (on top of Level 1), and Level 3 chemical hazard assessment capability (on top of Levels 1 and 2) — the levels are cumulative, Level 3 is the highest confidence, and bluesign-approved products map to this level.
Higg/Cascale MSI: a measurement tool, not a label
The Higg Materials Sustainability Index (MSI), administered by Cascale (formerly the Sustainable Apparel Coalition), is a life-cycle assessment (LCA) tool, not a certificate. With a cradle-to-gate scope, it scores environmental impact (climate, water, fossil fuels, and more) from raw-material production up to the point the material is ready for assembly. It does not stamp a fabric pass or fail; it lets you compare different material and process choices. The MSI should therefore be read as a design-stage decision-support tool, not a sourcing certification.
Mass balance or physical segregation: the real language of a claim
The most technical question to ask when reading a recycled claim is the chain-of-custody model. Under physical segregation, certified material is not physically mixed with non-certified material of the same type; GRS and RCS use this model, which permits product-specific, precise claims such as "50% of this fabric is recycled." Under the mass balance model, certified and non-certified inputs may be physically mixed and kept apart only through bookkeeping — here only aggregate, vaguer claims such as "we use X% recycled material" are possible. The two are not the same; asking which model applies when reading a supplier document determines how much weight a claim carries.
| Standard / tool | What it certifies | Focus (product/process) | Minimum threshold / model | Chain of custody |
|---|---|---|---|---|
| RCS (Textile Exchange) | Recycled content only | Product-content | ≥5%; Recycled 100 ≥95% | Physical segregation |
| GRS (Textile Exchange) | Recycled + social + environmental + chemical | Product + process | ≥20% (B2B), ≥50% (label) | Physical segregation |
| OEKO-TEX STANDARD 100 | Harmful-substance limits in finished product | Product-output | 4 use classes (I-IV) | None (product test) |
| OEKO-TEX STeP | Facility environmental/chemical/social conditions | Process-facility | Module-based score | None (facility audit) |
| OEKO-TEX MADE IN GREEN | STANDARD 100 + STeP + traceability | Product + process | Both certificates required | Traceable label |
| bluesign | Supply-chain input-stream chemistry | Process-input | Approved-product database (bluefinder) | Entire chain |
| ZDHC MRSL | Banned chemicals in manufacturing input | Process-input | Conformance Level 1-3 | Input formulation |
| Higg/Cascale MSI | Environmental impact (LCA score) | Product-design | Cradle-to-gate, no threshold | None (measurement tool) |
Practical reading: decoding a supplier pack
- If there is a recycled claim: is it GRS or RCS? GRS also covers the social/environmental layer; RCS is content only. Ask the percentage (20%/50%) and whether it is physical segregation or mass balance.
- If health/skin safety is in question: OEKO-TEX STANDARD 100 and which product class (babies = Class I, strictest).
- If manufacturing responsibility is in question: STeP, bluesign, and/or a ZDHC MRSL level — these audit the facility/chemistry, not product content.
- If you need product + process + traceability in one label: composite standards such as MADE IN GREEN or GRS fill that gap.
- For comparison/design decisions: Higg/Cascale MSI is a material-selection score, not a label; using it as a marketing claim is misleading.