UK proposes mandatory classification and labelling for 20 hazardous chemical substances

HSE has notified the WTO of a proposal to amend the GB mandatory classification and labelling list with new or revised entries for 20 hazardous chemical substances, under the GB CLP Regulation, the UK's own version of EU Regulation (EC) No 1272/2008 that has run separately from EU CLP since the end of the Brexit transition period.

HSE is the competent authority for classification decisions in Great Britain. A substance on the GB MCL list carries a legally binding classification, rather than being left to supplier self classification. Before any entry is added or changed, HSE publishes an Agency Opinion for that substance, and the Secretary of State then makes the formal decision, with the consent of the Scottish and Welsh governments. This notification covers the consultation stage for the current batch of 20 substances; the individual Agency Opinions are available from HSE's GB CLP publication table.

HSE cites protection of human health and the environment, proper functioning of the UK internal market, and regulatory harmonisation as the grounds for the proposal. It follows an earlier, larger proposal covering 60 substances notified in January 2026, which is still going through the same process.

Comments are due by 6 October 2026. HSE expects to adopt the decision around Q1 2027. Once adopted, the new classifications can be used voluntarily from Q1 2027, with mandatory compliance from Q3 2028.

Companies supplying substances or mixtures to the GB market should check whether any of the 20 substances are in their portfolio and track the outcome of the Agency Opinions, since a mandatory classification changes safety data sheet content, labelling, and in some cases triggers restriction or authorisation requirements tied to the hazard class. The full substance list and proposed classifications are in the GB MCL list spreadsheet published by HSE and can be found here. 

Source: WTO TBT Notification G/TBT/N/GBR/125, HSE GB Mandatory Classification and Labelling List