GB CLP REGULATORY UPDATE
On August 7, 2026, the United Kingdom notified the World Trade Organization (WTO) of a proposal to introduce new or revised mandatory classifications and labelling requirements for 20 hazardous chemical substances under the GB Classification, Labelling and Packaging Regulation.
The proposal is set out in WTO TBT notification G/TBT/N/GBR/125. Comments may be submitted until October 6, 2026. Adoption is expected in the first quarter of 2027, when voluntary application would begin, followed by mandatory application from the third quarter of 2028.
This is the second GB Mandatory Classification and Labelling (GB MCL) proposal notified to the WTO in 2026. It is separate from the earlier proposal covering 60 substances under G/TBT/N/GBR/113.
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Key Proposal Details at a Glance
| Item | Proposed arrangement |
|---|---|
| WTO notification | G/TBT/N/GBR/125 |
| Responsible authority | UK Health and Safety Executive (HSE) |
| Scope | New or revised GB MCL entries for 20 hazardous substances |
| Comment deadline | October 6, 2026 |
| Expected adoption | Q1 2027 |
| Voluntary application | From Q1 2027 |
| Mandatory application | From Q3 2028 |
| Current status | Proposal; not yet a binding GB MCL update |
How Does This Proposal Relate to the Earlier 60-Substance Notification?
In January 2026, the UK submitted WTO notification G/TBT/N/GBR/113, proposing new or revised mandatory classifications for 60 substances. Its comment period closed on March 27, 2026.
The new G/TBT/N/GBR/125 notification covers a different group of 20 substances and establishes a separate proposed timetable. The earlier notification indicated mandatory application from Q4 2028, while the second proposal indicates mandatory application from Q3 2028.
Companies should therefore screen their portfolios against both notifications and monitor the final HSE decisions separately.
What Does Inclusion in the GB MCL List Mean?
The GB MCL List contains legally binding classifications and hazard labelling information for substances placed on the market in Great Britain - England, Scotland and Wales.
When a substance is included in the list, suppliers must apply the specified mandatory classification and labelling. For a mixture containing a listed substance, the mandatory classification must generally be used in the classification calculation unless robust scientific data are available to classify the mixture directly.
The current proposal remains subject to the regulatory process. The proposed classifications should therefore be used for impact assessment and transition planning, rather than treated as already binding requirements.
Which Substances Are Covered by the Second Proposal?
The 20 substances can be divided into three main groups: nine proposed reproductive toxicants, four proposed carcinogens and seven substances subject to other health, physical or environmental hazard classifications.
Nine Substances Proposed for Reproductive Toxicity Category 1B
| Substance or substance group | CAS number(s) | Main proposed classification |
|---|---|---|
| Piperonal | 120-57-0 | Repr. 1B, H360FD; Skin Sens. 1 |
| N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine (6PPD) | 793-24-8 | Repr. 1B, H360Fd, together with acute toxicity, target-organ, sensitisation and aquatic hazard classifications |
| Bisphenol F | 620-92-8 | Repr. 1B, H360F |
| 3,5-Dimethylpyrazole | 67-51-6 | Repr. 1B, H360Fd, together with Acute Tox. 4 and STOT RE 2 |
| Ulexite and calcined ulexite | 1319-33-1; 92908-33-3 | Repr. 1B, H360FD |
| Colemanite and related calcined forms | 1318-33-8; 854267-07-5; 92908-12-8 | Repr. 1B, H360FD |
| Tincalconite | 12045-88-4 | Repr. 1B, H360FD |
| 2-Pyrrolidone | 616-45-5 | Repr. 1B, H360D, with a proposed specific concentration limit of C ≥ 3% |
| Tebuconazole | 107534-96-3 | Repr. 1B, H360Df, together with acute toxicity, target-organ and aquatic hazard classifications |
The proposal includes a specific rule for the listed boron compounds. Under proposed Note 11, a mixture would need to be classified as toxic to reproduction where the combined concentration of individual boron compounds classified as reproductive toxicants is at least 0.3%.
This means that companies should assess the combined concentration rather than reviewing each listed boron compound in isolation.
Four Entries Proposed for Carcinogenicity Category 1B
Four related ethylenediaminetetramethylene phosphonic acid entries are proposed for classification as Carc. 1B, H350:
The parent acid, CAS 1429-50-1;
Calcium sodium salt, CAS 85480-89-3;
Potassium salt, CAS 34274-30-1; and
Sodium salt, CAS 22036-77-7.
If adopted, these classifications may affect hazard communication and may also trigger consequences under other legislation where controls are linked to carcinogenicity classifications.
Seven Substances with Other Proposed Hazard Classifications
| Substance | CAS number(s) | Principal proposed hazard focus |
|---|---|---|
| 2,2',6,6'-Tetra-tert-butyl-4,4'-methylenediphenol | 118-82-1 | Aquatic Chronic 4 |
| Trihydrogen pentapotassium di(peroxomonosulfate) di(sulfate) | 70693-62-8 | Acute toxicity, skin corrosion, serious eye damage, target-organ toxicity and aquatic hazards |
| Thymol | 89-83-8 | Acute toxicity, skin corrosion, eye damage, target-organ toxicity and aquatic hazards |
| Bronopol | 52-51-7 | Acute toxicity through multiple exposure routes, skin corrosion, eye damage, skin sensitisation and aquatic hazards |
| Thermally treated garlic juice | Not specified | Skin Sens. 1B |
| Eugenol | 97-53-0 | Acute Tox. 4, STOT SE 3 and Skin Sens. 1B |
| Tea tree oil | 85085-48-9; 68647-73-4 | Flammability, acute toxicity, aspiration hazard, skin irritation, skin sensitisation and aquatic hazards |
The complete proposed classifications, hazard statements, pictograms, signal words, specific concentration limits, acute toxicity estimates and M-factors are available in the official notified substance table.
What Should Chemical Suppliers Do?
Screen Substance and Mixture Portfolios
Review substances, formulations and supplier information against the complete notified list. Screening should consider CAS numbers, alternative substance names and grouped entries such as ulexite, colemanite and tea tree oil.
Reassess Mixture Classification
Determine whether the proposed classifications would change the classification of mixtures. Particular attention should be given to the proposed 0.3% combined concentration rule for listed reproductive-toxic boron compounds.
Prepare for GB-Specific SDS and Label Changes
Identify affected Safety Data Sheets, labels and packaging information. Companies may begin preparing draft updates and transition plans, but the proposed classifications should not be represented as mandatory until the relevant GB MCL decision is adopted.
The removal of the standalone GB classification and labelling notification requirement from May 21, 2026 does not remove the duty to classify, label and package chemicals or apply legally binding GB MCL entries. See REACH24H's explanation of the 2026 GB CLP notification changes.
Assess Wider Regulatory Consequences
A new carcinogenicity or reproductive toxicity classification may affect obligations or controls under other regulatory regimes. Companies should assess these consequences separately under the applicable UK REACH, biocidal product, plant protection product, workplace safety and supply-chain requirements.
Submit Relevant Evidence Before the Deadline
Companies holding scientific, technical or socioeconomic information relevant to the proposed classifications should consider submitting comments by October 6, 2026 through the contact identified in the WTO notification.
How REACH24H Can Help
REACH24H can support companies supplying substances and mixtures to Great Britain with:
Screening substance and mixture portfolios against proposed and adopted GB MCL entries;
Assessing classification and mixture-calculation implications;
Preparing or reviewing Great Britain-specific SDSs and chemical labels; and
Monitoring GB CLP and GB MCL decisions, transition periods and implementation dates.
For support with hazard classification, SDS preparation or label review, explore REACH24H's Global GHS, SDS/MSDS and Label Compliance services or submit a compliance inquiry.
Need support with GB CLP classification, SDS or label requirements?
Submit your substance or mixture information for an initial compliance assessment.
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