Great Britain HSE Proposes Stronger Dichloromethane Carcinogenic And Mutagenic Classification

Dichloromethane, also called methylene chloride, has Chemical Abstracts Service number 75-09-2 and European Community number 200-838-9. It is currently listed under the Great Britain Mandatory Classification and Labelling regime as Carcinogenicity Category 2, hazard statement H351, suspected of causing cancer.

HSE now proposes Mutagenicity Category 2, H341, suspected of causing genetic defects, and Carcinogenicity Category 1B, H350, may cause cancer. The opinion follows HSE’s September 2025 Technical Report and agrees with the European Chemicals Agency Committee for Risk Assessment position.

This is not an adopted classification. A future decision and amendment to the Great Britain Mandatory Classification and Labelling List would be needed before suppliers face a new legal classification deadline. Northern Ireland is outside the geographical scope because European Union Classification, Labelling and Packaging rules continue to apply there.

What Changes Now And What May Change Later

No immediate relabelling, repackaging or safety data sheet deadline arises from the opinion. HSE’s impact analysis uses an approximately 18-month relabelling assumption for costing, but this is not a fixed legal transition. The opinion also sets no specific concentration limit, M-factor, acute toxicity estimate, occupational exposure limit or use restriction.

HSE expects no significant direct policy or socio-economic impacts from the proposal. Its assessment treats familiarisation and routine label updates as established industry practice.

Dichloromethane is used in pesticide manufacture, washing and cleaning, extraction, adhesives and sealants, coatings, biocides, heat-transfer fluids and some spray adhesives. If Category 1B carcinogenicity is adopted, manufacturers, importers and formulators would need to reassess mixture classification, labels, packaging and safety data sheets using the applicable generic concentration rules unless a specific limit is later established.

Employers should also anticipate a higher risk-management signal under the Control of Substances Hazardous to Health Regulations. Existing workplace duties and the current UK REACH restrictions on dichloromethane paint strippers remain unchanged. A Category 1B classification could inform later UK REACH or substances-of-very-high-concern action, but neither follows automatically from this opinion.

Classification can have consequences beyond the label. Procurement rules, customer specifications, substitution programmes and waste decisions may react before legal adoption. Companies should therefore identify dichloromethane in substances, mixtures and processes, but keep implementation plans conditional so that a proposal is not treated as law.

Manufacturers and importers should compare current dossiers with the HSE rationale. Distributors and retailers should map affected stock and Great Britain versus Northern Ireland supply routes. Downstream users and employers should verify exposure controls and feasible alternatives while monitoring the next HSE and ministerial steps.