Further UK Technical Reports on Chemicals Released in 2025

By Susana Planas MunGavin BSc., MSc, Senior Regulatory Specialist, Supply Chain Team, UL Solutions

In September 2025, the Health and Safety Executive (HSE), acting in its capacity as the Great Britain (GB) Classification, Labelling and Packaging (CLP) Agency, released a new batch of Technical Reports of hazardous chemicals, addressing seven chemicals registered with the European Chemicals Agency (ECHA) as per the EU Regulation EC/1907/2006 concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals and two hazardous active substances used in Plant Protection Products. These include new or revised entries that will be added to the next update of the Great Britain Mandatory and Classification List (GB MCL).

The classification and labelling of substances and mixtures placed on the market in Great Britain must comply with the criteria for classification set out under the current GB MCL, 6th Edition, last updated in February 2025. The GB MCL retained EU harmonized classification and labeling criteria in force in the European Union until December 31, 2020. The GB MCL is updated and amended by the HSE, accordingly, as a result of new agreed criteria based on the conclusions of the Technical Reports.

Technical Reports released in September 2025 concern the classification and labelling of the following REACH-registered chemicals:

• 3,4-Dimethyl-1H-pyrazol-1-ium dihydrogen phosphate (3,4-DMPP); (CAS No. 202842-98-6)
• 3,4-Dimethyl-1H-pyrazole; (CAS No. 2820-37-3)
• Acetophenone; (CAS No. 98-86-2)
• Ethylene bis[3,3-bis(3-tert-butyl-4-hydroxyphenyl)butyrate]; (CAS No. 32509-66-3)
• 2-Ethylhexyl (2E)-3-(4-methoxyphenyl)acrylate; (CAS No. 83834-59-7)
• 2-(2H-Benzotriazol-2-yl)-p-cresol; (CAS No. 2440-22-4)
• Dichloromethane; (CAS No. 75-09-2)

Also in September 2025, two further reports were released on the classification and labelling concerning the following two hazardous active ingredients used in Plant Protection Products:

• Sulcotrione (CAS No. 99105-77-8). This substance will be classified as Carcinogens, category 2; H351 (Suspected of causing cancer), in the revised GB MCL List.
• Fluazaindolizine (CAS No. 1254304-22-7). This substance is not currently listed under the GB MCL List. The following hazard classes and categories will be included in the next update of the GB MCL List:
  • Acute Toxicity via the oral route as Acute Tox. 4; H302 (Harmful if swallowed)
  • Specific target organ toxicity – repeated exposure as STOT RE 2; H373 (liver)
  • Aquatic Chronic 2, H411 (Toxic to aquatic life with long lasting effects)

The HSE’s next steps for the final implementation of these new and revised classification and labelling criteria will be the publication of Technical Opinions and final GB MCL Decisions, for their inclusion in the next GB MCL to be released.

The final ministers' decision and consent of the Devolved Administrations (Scotland and Wales) are required for the GB MCL List to be updated with the new or revised entry.

A full list of GB MCL technical reports is available on the HSE MCL Excel Table.

Recommended action items

• Review the Technical Reports released in September 2025 on the conclusions on the revised or new classification and labeling criteria proposed for hazardous substances.
• Ensure substances are being used or handled at the workplace in accordance with the existing GB MCL classification and labeling criteria.
• Review and update, as appropriate, associated substance documentation, such as Safety Data Sheets and product labels.

References

• HSE publications supporting ministerial decisions on new or revised GB mandatory classification and labelling
• GB Mandatory Classification and Labelling (MCL) List, 6th Edition, February 15, 2025