Key takeaway
What This Development Means
The European Chemicals Agency is consulting until 20 November 2026 on harmonised classification and labelling proposals for nine organic anhydrides. Respiratory and skin sensitisation feature across the group, with additional endpoints for selected substances. The consultation changes no classification now, but could precede binding EU Classification, Labelling and Packaging amendments.
Do companies need to relabel organic anhydrides now?
No. ECHA is gathering evidence on proposals. Current harmonised classifications and self-classification duties continue. Binding label changes would require a later European Commission delegated act, with its own publication, entry-into-force and application provisions.
Which hazard is common across all nine proposals?
Respiratory sensitisation and skin sensitisation are open for comment for each substance. Some proposals add acute toxicity, irritation, carcinogenicity, mutagenicity or specific target organ toxicity. Stakeholders should check each ECHA dossier rather than extrapolating from the group.
Source basis: European Chemicals Agency, harmonised classification and labelling consultation
Organic Anhydride Classification Proposals Cover Nine Substances
The European Chemicals Agency (ECHA) has opened an organic anhydride classification consultation covering nine substances under the Classification, Labelling and Packaging (CLP) Regulation. Comments opened on 21 September and close on 20 November 2026.
The substances are:
- 1,2,3,6-tetrahydromethyl-3,6-methanophthalic anhydride, CAS 25134-21-8
- chlorendic anhydride, CAS 115-27-5
- 4-chloroformylphthalic anhydride, CAS 1204-28-0
- 4,4'-biphthalic dianhydride, CAS 2420-87-3
- 4,4'-oxydiphthalic anhydride, CAS 1823-59-2
- 5,5'-sulfonyldi(2-benzofuran-1,3-dione), CAS 2540-99-0
- benzophenone-3,3':4,4'-tetracarboxylic dianhydride, CAS 2421-28-5
- ethylene bis[1,3-dihydro-1,3-dioxo-isobenzofuran-5-carboxylate], CAS 1732-96-3
- tetrabromophthalic anhydride, CAS 632-79-1
Respiratory and skin sensitisation are open for comment for all nine. Selected dossiers also cover acute oral or inhalation toxicity, skin corrosion or irritation, serious eye damage or irritation, carcinogenicity, germ-cell mutagenicity and specific target organ toxicity after single exposure. The precise proposal differs by substance, so companies should use the dossier-specific ECHA table rather than treating the group as having one common classification.
No Immediate CLP Label Change Follows From Consultation
The consultation does not amend Annex VI to the CLP Regulation. Current harmonised classifications and suppliers' self-classification duties remain in force. After consultation, ECHA's Committee for Risk Assessment may adopt opinions. The European Commission and Member States would then decide whether to add or amend binding classifications through a delegated act, normally with separate entry-into-force and application dates.
If the proposals are eventually adopted, manufacturers and importers may need to update classification, labels, packaging and safety data sheets. Downstream consequences can extend to workplace risk assessment, storage, transport, procurement specifications and sectoral rules that refer to CLP hazard classes. No new concentration threshold, exemption or transitional period is created by the consultation itself.
Companies should identify the nine CAS numbers across substance inventories, mixtures and supplier declarations. Relevant study owners should compare evidence with the dossier endpoints and submit robust data, including information that could refine category severity or route-specific conclusions, by the deadline.
ECHA asks consultees to focus on the hazard classes open for comment and to support submissions with reliable scientific evidence. Use patterns and exposure controls may inform later risk management, but they do not replace hazard evidence in the CLH assessment.
Foresight analysis: the common sensitisation focus points to a possible group-wide occupational issue, but the broader endpoints vary significantly. Portfolio-level screening is efficient, while dossier-level evidence is essential. Assuming identical hazards across all nine could lead either to missed obligations or unnecessary substitution.
Screen the nine CAS numbers now and coordinate scientific comments before 20 November 2026 where data are relevant to an open hazard class.
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