The eleventh revised edition of the United Nations Globally Harmonized System of Classification and Labelling of Chemicals — UN GHS Rev 11 — was published on September 12, 2025 by UNECE in Geneva. Although UN GHS revisions appear every two years, Rev 11 is more substantive than the incremental Rev 8, 9, and 10 that preceded it. It introduces a new environmental hazard class for substances contributing to global warming, restructures how aerosols and chemicals under pressure interact with other hazard classes, formalises non-animal test methods for skin sensitization, and adds new guidance on simple asphyxiants. Label examples and precautionary statements are refreshed, and several rationalisations clean up legacy formatting.
This guide explains every change UN GHS Rev 11 makes against the tenth revised edition (UN GHS Rev 10, July 2023), maps the changes to the chapters and annexes of the Purple Book, and reviews adoption status across major jurisdictions as of May 2026. The intended audience is regulatory affairs professionals, SDS authors, EHS managers, and product compliance teams who need to know what to monitor, what to update, and when. UN GHS Rev 11 is not yet binding in any major jurisdiction, but adoption proposals are in motion across the EU, and other regulators are watching closely.
At a glance
- Document: ST/SG/AC.10/30/Rev.11 — Globally Harmonized System of Classification and Labelling of Chemicals (Eleventh Revised Edition)
- Published: September 12, 2025 by UNECE
- Adopted: December 6, 2024 by the UN Sub-Committee of Experts on the Globally Harmonized System (twelfth session)
- Languages available: English, French, Spanish (free electronic version on UNECE portal)
- Predecessor: UN GHS Rev 10, published July 27, 2023
- Major additions: New hazard class “Hazardous to the atmospheric system” (contributes to global warming); new Annex 11 on simple asphyxiants
- Adoption status (May 2026): No jurisdiction has fully transposed Rev 11; EU is preparing partial adoption (aerosols, skin sensitisers in mixtures); US OSHA HCS still aligned to Rev 7
- Related tools: Label Constructor · ATE Calculator
Table of Contents
- Background: UN GHS revision cycle
- The Five Major Changes in Rev 11
- Side-by-Side: Rev 10 vs Rev 11
- Adoption Status by Jurisdiction (May 2026)
- Practical Impact: What to Do Now
- Frequently Asked Questions
Background: UN GHS revision cycle
UN GHS — sometimes called the “Purple Book” for the colour of its cover — is the master reference that national chemical safety regimes derive from. It was first adopted in 2002 by the UN Economic and Social Council (ECOSOC) and has been published as a revised edition every two years since 2003. The Sub-Committee of Experts on the GHS, which meets twice yearly under the UN Committee of Experts on the Transport of Dangerous Goods and the GHS, prepares each revision. Once the Sub-Committee adopts amendments, UNECE publishes them as the next revised edition of the document.
UN GHS itself is not law. It becomes legally binding only when a national or regional authority transposes its content into local regulation — for example, the European Union does this through Adaptations to Technical Progress (ATPs) of the CLP Regulation; the United States through the OSHA Hazard Communication Standard (HCS); Canada through the Hazardous Products Regulations (HPR); Japan through Industrial Safety and Health Law amendments; and so on. Each jurisdiction selects which “building blocks” of UN GHS to adopt, and at which revision level. This is why an EU label and a US label for the same substance can look meaningfully different even though both jurisdictions claim to follow GHS.
The biennial revision cycle means that as one revision is rolling out into national regulation, the next one is already in preparation. UN GHS Rev 10 was published in July 2023; the amendments that became Rev 11 were adopted in December 2024 and announced by UNECE in July 2025; the document was published in September 2025. UN GHS Rev 12 is now in preparation, with adoption likely by late 2026.
UN GHS revisions, 2003 to 2025. Each revision is published every two years by UNSCEGHS in Geneva. Revisions 7 and 8 are the most widely implemented baselines as of 2026.
The Five Major Changes in Rev 11
UN GHS Rev 11 makes substantive changes across five distinct areas. Below, each is summarised against the chapter or annex where it lives in the Purple Book.
1. New hazard class: “Hazardous to the atmospheric system” (Chapter 4.2)
The most prominent change is a wholesale restructuring of Chapter 4.2, which addresses environmental hazards to the atmosphere. The old chapter — titled “Hazardous to the ozone layer” — had a single hazard class for substances listed in the Montreal Protocol annexes. Rev 11 renames the chapter to “Hazardous to the atmospheric system” and expands it to cover two parallel hazard classes:
- Hazardous to the ozone layer — preserved from Rev 10, with the abbreviation “ODP” replaced by the full term “Ozone Depleting Potential” throughout for clarity.
- Hazardous by contributing to global warming — new in Rev 11. Classifies substances and mixtures based on their Global Warming Potential (GWP), defined as cumulative radiative forcing relative to carbon dioxide over a specified time horizon, including both direct and indirect effects.
The new global warming class draws its scope from substances controlled under the Montreal Protocol annexes, particularly the Kigali Amendment which addresses hydrofluorocarbons (HFCs). Refrigerant gases, certain aerosol propellants, and specialty industrial gases are most directly affected.
Labelling for the new class introduces a precautionary statement matrix anchored on P502 (disposal guidance emphasizing recycling). Suppliers will need to add P502 — alongside hazard statements specific to GWP categories — to substances and mixtures that fall in the new class once Rev 11 is transposed into national regulation.
2. Aerosols and chemicals under pressure clarified (Chapter 2.3)
Chapter 2.3 has long been one of the more confusing parts of the Purple Book. It covers two related but distinct hazard classes — Aerosols (Section 2.3.1) and Chemicals Under Pressure (Section 2.3.2) — that frequently overlap with neighbouring classes such as Flammable Gases (2.2), Pressurized Gases (2.5), Flammable Liquids (2.6), and Flammable Solids (2.7).
Rev 11 clarifies these boundaries by stating explicitly that:
- Aerosols no longer fall under Chapter 2.2, 2.5, 2.6, or 2.7 by default. They may still be classified into those classes based on their contents, but the aerosol classification itself sits exclusively in Section 2.3.1.
- Chemicals under pressure similarly are excluded from those overlapping classes by definition, while remaining open to additional classifications based on their contents.
Table 2.3.1 has also been supplemented with additional test content for distinguishing aerosol categories. The practical effect is to reduce duplicate classification work and prevent labels from carrying redundant or conflicting hazard information about the same physical hazard.
3. Non-animal test methods for skin sensitization (Chapter 3.4)
Chapter 3.4 — Skin Sensitization — receives one of the most consequential updates in Rev 11 from the perspective of hazard assessment workflow. The chapter now formally accepts a wider range of evidence sources for classification, including:
- Human predictive patch tests
- Epidemiological studies, case studies, case reports, and medical histories
- Diagnostic patch tests and medical examination reports
- Poison control centre data
- Validated non-animal in vitro and in chemico methods, including OECD Test Guidelines 442C, 442D, and 442E assembled into an integrated approach to testing and assessment
This change reflects a global push, particularly in the EU and Asia-Pacific, to reduce animal testing for chemical safety. It does not eliminate the use of animal data already on file, but it gives classifiers a clearer pathway to use modern alternative methods. Mixtures present additional complexity — the new guidance acknowledges that a stepwise approach combining test data on the mixture itself with bridging principles for analogous mixtures remains the workflow.
For mixture classification work that depends on Annex 9 arithmetic, our ATE Calculator implements the GHS Rev 7 formulas; Rev 11 has not changed the underlying ATE arithmetic.
4. New Annex 11: Simple asphyxiants
Rev 11 introduces a brand new section in Annex 11 (Guidance on other hazards not leading to classification) dedicated to simple asphyxiants — gases or vapours that displace oxygen from the breathing air without otherwise being classified as toxic. Examples include nitrogen, carbon dioxide, methane, argon, and helium.
Simple asphyxiants do not meet the criteria for Acute Toxicity classification, because they have no inherent toxicity at normal pressures. The hazard arises purely from oxygen displacement in confined or poorly ventilated areas. Until Rev 11, there was no harmonised guidance on how to communicate this hazard, leaving the decision to national regulators or to suppliers themselves.
The new Annex 11 guidance:
- Defines simple asphyxiants and distinguishes them from chemical asphyxiants (which interfere with oxygen transport in blood)
- Provides recommended labelling phrases — competent authorities may require, or suppliers may choose to use, phrases such as “May displace oxygen and be fatal” alongside the signal word “Danger” and storage advice (“Store in well-ventilated place”)
- Offers SDS Section 2 guidance on how to flag the hazard even without formal classification
This is guidance, not a hazard class — meaning suppliers are not compelled to apply it unless a competent authority requires it. But the harmonised text gives industry a stable reference and lets jurisdictions adopt the language verbatim if they choose.
5. Updated label examples and precautionary statements
Rev 11 includes a substantial cleanup of label examples in Annex 7 and a rationalisation of precautionary statements in Annex 3.
Notable changes:
- New precautionary statements P322 and P323 added to the catalogue covering Acute Toxicity scenarios.
- P502 repositioned to support the new global warming hazard class.
- Seven label sample images replaced with redrawn versions clarifying combination packaging vs single packaging requirements.
- Black background frame for the product name removed from the new label example illustrations.
- The note allowing inner packaging to use the UN Model Regulations flammable liquid pictogram in place of the GHS pictogram has been removed.
- Rules clarifying how transport pictograms and GHS pictograms coexist on the same label have been added.
- Several precautionary statements have been rephrased to improve plain-language comprehension without changing their underlying intent.
The net effect for SDS authors is a small batch of new statement codes to add to existing libraries (P322, P323, and the global warming-specific statements) and updated example references when training new staff on label drafting.
Side-by-Side: Rev 10 vs Rev 11
A condensed comparison of the most material changes:
| Topic | Rev 10 (July 2023) | Rev 11 (Sept 2025) |
|---|---|---|
| Chapter 4.2 title | Hazardous to the ozone layer | Hazardous to the atmospheric system |
| Chapter 4.2 hazard classes | 1 (ozone layer only) | 2 (ozone layer + global warming) |
| GWP-based classification | Not addressed | New criteria, new precautionary statements |
| Aerosol overlap with Ch. 2.2/2.5/2.6/2.7 | Implicit | Explicitly excluded |
| Chemicals under pressure overlap | Implicit | Explicitly excluded |
| Skin sensitization data sources | Conventional + limited alternatives | Expanded; non-animal methods formalized |
| Simple asphyxiants guidance | None | New Annex 11 section |
| New precautionary statements | — | P322, P323, GWP-specific |
| Label examples | Legacy | Refreshed (7 redrawn) |
| ODP terminology | ”ODP” (acronym) | “Ozone Depleting Potential” (full term) |
This is a high-level summary. The full text of changes runs to several hundred amendments across the Purple Book and is detailed in the consolidated Rev 11 document on the UNECE portal.
Adoption Status by Jurisdiction (May 2026)
UN GHS Rev 11 is not legally binding anywhere as of this writing. National adoption requires regulatory action — drafting, consultation, adoption, and a transition period. Below is the current status in major jurisdictions; see our country-by-country UN GHS implementation map for full coverage.
European Union (CLP)
The EU CLP Regulation is currently aligned through the 12th ATP with GHS Revisions 6 and 7. A draft Delegated Regulation has been in preparation since 2025 to align CLP with GHS Revisions 8, 9, and 10, and to partially implement Rev 11 for aerosols (Chapter 2.3) and skin sensitisers in mixtures (Chapter 3.4). Full transposition of the new global warming hazard class is not part of the current draft. Adoption was originally planned for the fourth quarter of 2025; as of May 2026 the regulation is in process. Until it is published, EU compliance continues to follow Rev 6/7 logic.
United States (OSHA HCS)
US OSHA’s Hazard Communication Standard (HCS) 2024 aligns with GHS Revision 7. The first compliance deadline — May 19, 2026 for substance manufacturers — has just arrived; the next four-year transition runs through 2028 for mixtures and employer obligations. There is no public OSHA rulemaking activity on Rev 11. Realistically, US adoption of Rev 11 (or any later revision) is unlikely before 2030. See our OSHA HCS 2024 changes guide for the active US deadlines.
Canada (WHMIS)
The Canadian Hazardous Products Regulations (HPR) were aligned with GHS Revision 7 in 2022. Health Canada has not announced timelines for Rev 11 adoption. As Canadian regulatory practice tends to track US OSHA closely, movement is unlikely before US action.
Japan, China, South Korea
The Japanese standards JIS Z 7252 (classification) and JIS Z 7253 (labelling and SDS) reference GHS Rev 6. China’s GB 30000 series is aligned with Rev 4. South Korea’s K-GHS implementation under the Industrial Safety and Health Act is aligned with Rev 6. None of these jurisdictions has published a Rev 11 adoption schedule as of May 2026.
Other major jurisdictions
Brazil (ABNT NBR 14725) is aligned with Rev 7 since 2023; the GCC (GSO 2017) with Rev 5; Australia’s Model WHS Regulations with Rev 7. In short, no jurisdiction is on Rev 11 as of May 2026, and most are still finishing transposition of earlier revisions. Suppliers can monitor without making changes today.
Practical Impact: What to Do Now
Rev 11 is a planning horizon item, not a near-term compliance task. The right posture for May 2026 is:
Monitor. Subscribe to ECHA, OSHA, and your domestic chemical authority for rulemaking notices. The EU draft Delegated Regulation transposing partial Rev 11 is the most likely first national-level adoption.
Inventory affected products. If you market refrigerants, aerosol propellants, fire suppression agents, or any product containing controlled fluorinated gases, identify which of your products would fall into the new global warming hazard class once it is binding. The Montreal Protocol Annex F substances list (HFCs) is the starting point. This work is voluntary now but will be required when Rev 11 is transposed.
Audit aerosol and chemicals under pressure classifications. If your current SDSs cross-classify aerosols into Chapter 2.2 or 2.6 in addition to 2.3.1, you will likely need to revisit those entries during the next major SDS review cycle. The change is not retroactive — existing classifications remain valid until the relevant national regulation transposes Rev 11.
Plan training. SDS authors and label designers will need familiarisation with the new precautionary statements (P322, P323, GWP-specific) and updated label examples once your jurisdiction adopts Rev 11. A short refresher in the year following local adoption is typical practice.
No SDS rewrites required today. Until your jurisdiction transposes Rev 11, your existing SDSs and labels remain compliant. There is no “GHS Rev 11 deadline” floating in the air the way OSHA HCS 2024 deadlines are.
For label updates that are required — particularly for the 22nd ATP to CLP, which became applicable May 1, 2026 in the EU — our GHS Label Constructor generates compliant labels at all five CLP volume tiers.
Frequently Asked Questions
When was UN GHS Rev 11 published?
UN GHS Rev 11 was published by UNECE on September 12, 2025. The amendments that form the eleventh revised edition were adopted by the UN Sub-Committee of Experts on the GHS at its twelfth session on December 6, 2024. The document is identified as ST/SG/AC.10/30/Rev.11 and is available in English, French, and Spanish on the UNECE portal.
What is the new global warming hazard class in GHS Rev 11?
Rev 11 introduces a new hazard class titled “Hazardous by contributing to global warming” within a renamed Chapter 4.2 (“Hazardous to the atmospheric system”). Substances and mixtures are classified based on their Global Warming Potential (GWP) — a measure of cumulative radiative forcing relative to carbon dioxide. The class primarily affects refrigerant gases, certain aerosol propellants, and specialty industrial gases controlled under the Montreal Protocol’s Kigali Amendment. New precautionary statements, including P502 emphasising recycling at end of life, accompany the class.
When will my country adopt UN GHS Rev 11?
No major jurisdiction has adopted Rev 11 as of May 2026. The EU is preparing a Delegated Regulation that would partially implement Rev 11 (aerosols and skin sensitisers in mixtures only); adoption was originally planned for Q4 2025 and is in process. US OSHA HCS, Canadian WHMIS, Japanese JIS standards, and most other regimes are still on Rev 6 or 7. Realistic timelines for full Rev 11 adoption in major markets are 2027 to 2030.
Do I need to update my SDSs and labels for Rev 11 now?
No. Until your jurisdiction’s national regulator transposes Rev 11 into binding law, existing SDSs and labels prepared under the regulation in force remain compliant. The exception is voluntary alignment — some multinational suppliers prefer to update SDSs to the latest UN GHS revision in advance of national adoption to streamline future transitions. This is a business decision, not a compliance requirement.
Is GHS Rev 11 mandatory?
No. UN GHS itself is a non-binding recommendation published by UNECE. It becomes mandatory only when a national or regional authority transposes its content into local regulation, and even then jurisdictions select which “building blocks” to adopt. Suppliers comply with the local regulation in force in each jurisdiction where they place products on the market — not with UN GHS directly. This is the same building-block principle that explains why an EU label and a US label for the same chemical can look different even though both jurisdictions claim to follow GHS.
Key takeaways
- UN GHS Rev 11 was published September 12, 2025 and introduces a new global warming hazard class, refined aerosol and chemicals under pressure rules, formalised non-animal skin sensitization methods, and new simple asphyxiant guidance.
- No jurisdiction has adopted Rev 11 yet. EU partial adoption (aerosols, skin sensitisers) is in process; full transposition timelines elsewhere stretch to 2027-2030.
- The five major changes map cleanly to specific Purple Book chapters (4.2, 2.3, 3.4) and annexes (3, 7, 11), making the delta easy to track during regulatory monitoring.
- No SDS or label updates are required today for Rev 11 — but inventory and planning work for affected products (especially controlled fluorinated gases) starts being valuable now.
- The biennial revision cycle continues: UN GHS Rev 12 is in preparation and likely to be adopted by late 2026.
Related articles in this hub
- UN GHS Implementation by Country: 2026 Status Map — full adoption status across 22 jurisdictions
- OSHA HCS 2024 Changes: Hazard Communication Final Rule — what US compliance looks like in May 2026
- GHS Label Constructor — generate CLP-compliant labels at correct pictogram sizes
- ATE Calculator — GHS Rev 7 acute toxicity estimate arithmetic for mixtures
Sources
- United Nations Globally Harmonized System of Classification and Labelling of Chemicals (GHS Rev. 11, 2025). UN Economic Commission for Europe, document ST/SG/AC.10/30/Rev.11, published September 12, 2025. Available at: https://unece.org/transport/dangerous-goods/ghs-rev11-2025
- UNECE Announces Updates for the 11th Revised Edition of GHS. UNECE press notice, July 16, 2025. Summary of amendments adopted by the UN Sub-Committee of Experts on the GHS at its twelfth session on December 6, 2024.
- New Hazard Class in GHS Rev. 11: Global Warming Contributions Enter the Regulatory Framework. knoell, September 8, 2025. Industry analysis of Chapter 4.2 restructuring.
- UN GHS Revision 11 Released: Key Updates You Need to Know. REACH24H, October 23, 2025. Detailed breakdown of changes by chapter and annex.
- Concawe Report 26-1: Hazard classification and labelling of UVCB hydrocarbon substances. Concawe, January 2026. Section on EU CLP transposition status of GHS Rev 8-11.
- CLP Legislation overview. European Chemicals Agency (ECHA). Available at: https://echa.europa.eu/regulations/clp/legislation
- Annex VI to CLP — 22nd ATP applicable from 1 May 2026. ECHA, Delegated Regulation (EU) 2024/2564.
- Substance classification data referenced in this article is sourced from the GHSSymbols.com Hazards Database, derived from ECHA CLP Annex VI list of harmonised classifications, last synchronised in March 2026.