HSE Adds 12 Substances To GB Pesticide Co-formulant Register

The Health and Safety Executive (HSE) has announced the addition of 12 substances to Great Britain's register of unacceptable co-formulants. Its 5 November bulletin says affected plant protection products and adjuvants in Great Britain and Northern Ireland must be amended or withdrawn as soon as possible, and no later than 16 June 2028.

Substances and Territorial Scope

The additions include acetaldehyde, propylene oxide, cumene, the cyclic siloxanes D4, D5 and D6, bumetrizole and 1,4-dioxane. The register's entries 145–156 identify the substances and the grounds for their inclusion.

The register gives a general limit of 0.1% by weight for unintentional impurities in finished products, unless it specifies a different limit. This is an impurity provision, not permission to use a listed substance deliberately as a co-formulant.

Great Britain maintains its own register. HSE says the EU's addition of the same 12 substances through Commission Regulation (EU) 2026/1120 applies directly in Northern Ireland. HSE assessed the justification for each substance before including it in the GB register. HSE bulletin.

Withdrawal and Grace Periods

For plant protection products, the maximum grace period for sale and supply is three months after the individual authorisation is amended or withdrawn. Disposal, storage and use may continue for no more than 12 months after that date. These periods run from the individual authorisation decision, rather than automatically from June 2028.

Adjuvants have no grace period once removed from the Official List of Adjuvants. HSE places responsibility for checking formulations on authorisation holders and says it will contact holders where it has already identified affected products. HSE bulletin.