Pesticide adjuvants and the Official List of Adjuvants

Definition of an adjuvant

Adjuvants are authorised under Regulation (EC) 1107/2009 which defines 'adjuvants' as being:

'substances or preparations which consist of co-formulants or preparations containing one or more co-formulants, in the form in which they are supplied to the user and placed on the market to be mixed by the user with a plant protection product and which enhance its effectiveness or other pesticidal properties, referred to as 'adjuvants'.

Adjuvants are not plant protection products (PPPs); but, as they influence the way PPPs behave and the effects they have, they are subject to regulatory control.

The Official List of Adjuvants

The 'Official List' provides details of the adjuvant products that may be used with PPPs and the conditions of use to which they are subject.

Each officially listed adjuvant product is issued with an individual 'list entry' which specifies the identity of the adjuvant and the conditions that a user must comply with. At any point in time there will only ever be one extant list entry for each individual adjuvant product.

The Official List is published in full on the adjuvant database on the HSE website. Any additions and amendments are updated regularly on the website. A copy of the list entry is sent to the applicant upon issue.

To add a new product to the Official List, or to amend the conditions of an existing list entry, an application must be submitted with all the necessary data to show that the adjuvant itself is safe to use, and is also safe to use when mixed with the proposed PPPs. All applications are processed in a similar way to plant protection products.

Adjuvant database

List entry

The list entry specifies:

  • the 'identity' of the product (for example tradename, ADJ (registration) number, applicant and formulation details)
  • the conditions of use with which a user must comply when using the adjuvant with an authorised plant protection product - these are in addition to complying with the conditions of use as specified on the plant protection product label
  • the expiry date(s) for the conditions of the previous list entry where a new list entry has superseded the former, or where a product has been withdrawn from the list

Each list entry has a unique list entry number, issued following evaluation of an application. A new list entry number is allocated each time a new list entry is issued.

The list entry will be sent to the applicant at the successful conclusion of the evaluation and published as part of the Official List.

Example list entry.

Identity of an adjuvant

Product tradename

Any change to the tradename requires an application to amend the list entry.

Unique registration (ADJ) number

Every adjuvant product carries a unique product registration number, prefixed by 'ADJ', which we allocate upon issue of the first list entry for a new product.

This number will remain with this specific adjuvant product, unless there is a subsequent change to its identity such as a change in product tradename, applicant, classification or a major change to its formulation.

The applicant

The applicant, as specified in the Official Listing, has a different definition to that used for authorisation of plant protection products. The role of the applicant company is the party:

  • making the application to include an adjuvant on the list
  • responsible for meeting any data requirement
  • responsible for any literature produced directly on their behalf
  • who may request to have an adjuvant removed from the list

Any change of the applicant requires an application to amend the list entry.

It should be noted that there are no legal controls over companies marketing adjuvants (unless they are also the applicant company). Marketing company details are not included on the list entry and notification of changes to these companies are not required.


The formulation details referenced on the list entry will refer to the specification of the 'effective adjuvant component' (as detailed in Appendix 1 of the application form) and the 'recipe' of the formulation (as detailed in Appendix 2 of the application form – unacceptable co-formulants).

CRD4 application form

Any changes to the formulation must be the subject of an application to HSE.

Effective adjuvant component

The applicant must propose which constituent(s) in the formulation are the 'effective adjuvant component(s) or EAC. This is the constituent which is/are primarily responsible for giving the product its adjuvant properties, or in other words, the main active component of an adjuvant. Their identity and quantity will be the only part of the (otherwise confidential) formulation details which will be specified in the published list entry.

Contact HSE

How to apply

A company wishing to market an adjuvant for use with a plant protection product (PPP) in the UK must apply for its inclusion on the Official List of Adjuvants.

Currently applications for inclusion on the Official List of Adjuvants do not incur a fee.

The application must contain information demonstrating the safety of the adjuvant for the proposed uses.

Covering letter

You should submit a covering letter for each application. This is an important document since it helps us understand why you have submitted your application. The letter should detail:

  • the purpose of the application - for example to add an adjuvant to the Official List
  • the context of the application in relation to any previous list entries
  • brief details as to how you are supporting your application, for example the submission of reasoned scientific cases; the submission of new data. You may expand this information to provide details of how you are addressing each area of the assessment. This could take the form of an application overview.

Application form

You must submit an appropriate CRD 4 application form with every application.

Where you are applying for a new effective adjuvant component (EAC) or new source of EAC you must also submit information on the nomenclature of the EAC.

Information required on the EAC nomenclature

Previous relevant correspondence

You must submit, or refer to, copies of any previous relevant correspondence relating to your application, so that the assessment manager can access or trace all supporting information. Relevant correspondence can consist of letters and emails and may include the following:

  • reference to the current list entry for your product (refer to the appropriate COP number)
  • reference to the current list entry(s) for other product(s) that you are referencing in support of your application (for example for new products based on similarity to products that are already listed; for applications for inclusion of a source of an effective adjuvant component already authorised in another product).
  • copies of correspondence which clarifies data requirements (for example copies of correspondence on data requirements that must be addressed for your product.
  • other advice we have provided you with that relates to your application

Letter of access

If you are not submitting (or referring to) your own data, you will need to provide a letter from the appropriate data owner which allows us to access to their data.

Letters are required to cover all the data used to support your adjuvant, not just the data submitted in support of a specific application.

More on letters of access

Draft List Entry

The proposed uses for the adjuvant should ideally be submitted as a "draft List Entry". You can use the example list entry to help you. However, you may choose to submit draft labels as a means of explaining the proposed uses of the adjuvant.

Product label

You may submit a draft label with your application. Whilst we have no legal control over the marketing and advertisement of adjuvant products, we can provide advice on labelling relating to the use of the adjuvant in the covering letter accompanying the list entry.

It is your responsibility to ensure that any product literature is in accordance with both the conditions of use of the adjuvant as specified in the list entry and the pesticide authorisation.

A product can be removed from the official list if the marketed label or other literature does not comply with conditions in the list entry or the relevant plant protection product authorisation(s).

Guidance on the labelling of pesticide products is given in The Labelling Handbook. You may wish to use this guidance to help you produce a draft label for your adjuvant product.

Compatibility assurance statement

You must submit a compatibility assurance statement (CAS) with all applications for:

  • new products
  • new uses
  • formulation changes

This certifies that data or other evidence are available to demonstrate that the adjuvant may be safely used in a tank mixture with the recommended plant protection products (as to be specified in the new list entry). An application must be submitted to amend the list entry if changes are made to the recommended uses. A template for this CAS is provided.

CAS template

Data requirements you need to address

You must provide appropriate data or information on:

  • the adjuvant's identity, including its physical and chemical properties - adjuvant data requirements
  • for adjuvants intended for use in conjunction with PPPs on crops destined for human or animal consumption, we also need supporting residues data to demonstrate an acceptable risk to consumers - residues data requirements for adjuvants

We do not currently consider data relating to storage stability of the adjuvant; acute toxicity or operator exposure (but Classification, Labelling and Packaging (CLP) Regulation (EC 1272/2008) applies to these aspects); its efficacy or crop safety; or its fate and behaviour in the environment and its effects on non-target species (also subject to CLP).

How to address the data requirements

You may address the data requirements by:

  • submitting new data specific to the proposed EAC/formulation details/uses
  • submitting published studies or other information from scientific journals or other sources
  • referencing data that have already been evaluated by us in support of the same or another product
  • submitting a letter of access authorising us to access third party data that have already been evaluated in support of the same or another product
  • submitting a reasoned case as to why the data requirement is not applicable to the proposed application

All studies must be:

  • in English and
  • generated in line with relevant international test guidelines and the applicable requirements for good laboratory practice (GLP) compliance or official recognition

For all applications you must provide a summary of the submitted data and an assessment as to how these data support the proposed product and use(s). This summary can be in the format of an application overview.

A copy of all the data referenced in support of your application must be submitted (single paper copy, CD/Email or electronically).

Classification, Labelling and Packaging (CLP) Regulation (EC) 1272/2008

Adjuvants are subject to the Regulation on Classification, Labelling and Packaging (CLP) of Substances and Mixtures (EC) 1272/2008. All adjuvants being placed on the market must be classified and labelled in line with CLP.

Advice on labelling with regard to CLP.

You should provide details of proposed classification and labelling when you submit your application.

Incomplete applications

We do not accept incomplete applications. The only exception to this is if a letter of access from a third party is to be submitted separately. This does not apply to applications processed via the Admin Stream, when all supporting information must have been submitted, including letters of access, before an application can be accepted.

How your application will be processed

General information on where to submit applications, processing times and information sent out during evaluations is in our guide on the pesticide product application process.

Adjuvant applications are placed in our usual processing streams (read our guidance on processing timelines for further information):

  • applications which require a technical assessment (for example a new formulation, a new source of EAC, supporting residues data) will be considered to the same timeframe as an application for the authorisation of a PPP.
  • applications which do not require any technical input will be considered via the admin stream

Target date and what might impact upon the processing time

We will inform you of the target date for completion of your application once it has been accepted at the sift (except for admin applications where the short processing time makes this impractical).

For some applications we may need to seek further information from you. Any time spent seeking further information does not count towards our processing time of your application.

What happens after your application is completed

If your application is successful, we will inform you in the normal way.

Pesticide product application process

An electronic copy of the list entry will be included on the Adjuvant Database and new products will be added to the Official List of Adjuvants.

If your application involves a major change to the products, we will produce a list entry for both the 'new' product and the 'old' product. There will normally be a use-up period for 'old' products.

If your application is unsuccessful, we will explain the reasons why your application has been refused and specify what data requirements you need to address to obtain inclusion on the Official List of Adjuvants.

You can contact HSE to obtain a copy of the full official list, or you can consult the Adjuvants Database for information on those in the list.

What happens after a list entry has been included

We carry out regular checks to ensure that list entries are up to date.

If revocation action is taken against a pesticide or its uses which will affect your list entry, we will amend your entry.

Taking your product off the market

If you wish to withdraw your product from the market for a commercial reason you should contact us so that your list entry can be formally withdrawn. We do not charge a fee for carrying out this procedure.

Email [email protected] confirming:

  • details of the product you wish to withdraw
  • reasons for withdrawal
  • the withdrawal period you require to allow for a use up period of existing stock (usually up to 2 years)

Removing a use from your product

If you wish to withdraw a use from the list entry of your product you will need to apply for the commercial withdrawal of this use as a new list entry will need to be issued for the product.

In your application you must state why you wish the use to be withdrawn.


Adjuvants are not plant protection products (PPPs); but, as they influence the way PPPs behave and the effects they have, they are subject to regulatory control.

Schedule 2 to the Plant Protection Products Regulations 2011 (SI 2011/2131) sets out the arrangements for authorising the use of adjuvants in the UK. This regulation carries forward long-standing national rules, as permitted by Art. 81(3) of the Regulation (EC) 1107.

HSE interprets the control over the use of the adjuvant with the PPP as being at the point when the adjuvant is in physical contact with the PPP in the tank. The example list entry includes the specific conditions of use relating to controls over use. Any change to these conditions requires an application to amend the list entry.

The regulations enable Ministers to:

  1. Set data requirements which must be met for an adjuvant to appear on the Official List of Adjuvants. These data requirements (adjuvant data requirements and residues data requirements) form the basis of the application evaluated by HSE to determine the safe conditions of use of the adjuvant with an authorised plant protection product. Inclusion on the Official List of Adjuvants cannot be given subject to confirmatory data requirements.
  2. Determine the conditions to which the use of the adjuvant with a PPP are subject. These conditions of use are published on the list entry for each adjuvant product. These may be amended for safety reasons or at the request of the applicant.
  3. Set further requirements in the light of available information relating to the use of the adjuvant with authorised PPPs. This may result from a review of an individual or group of adjuvants. If an adjuvant fails to pass a review, the product may be removed from the official list. Inclusion on the Official List of Adjuvants cannot be given subject to confirmatory data requirements.
  4. Remove an adjuvant from the official list for a variety of reasons:
    • if the applicant fails to comply with any data requirements (as part of an application for official listing, or review)
    • contains an unacceptable co-formulant
    • if any relevant product literature is not in accordance with the published conditions of use of the adjuvant, (relevant literature includes the product labelling, any accompanying leaflet, or any other literature describing the product produced by the applicant)
    • for safety reasons
    • at the request of the applicant company

Although there are no direct legal controls over the marketing and advertisement of adjuvants, an adjuvant may be removed from the list if the label or any other relevant literature promotes the use of an adjuvant with a PPP in a way that would either contravene the conditions of use of the adjuvant as detailed in the list entry, or the PPP authorisation. HSE provides advice on the adjuvant label text in their letter accompanying the list entry for guidance.

Other relevant legislation

The aspects that are not controlled under the regulations (for example storage, operator protection prior to use, environmental and toxicological classification of adjuvants) are controlled by other legislation:

  • the Health and Safety at Work Act, 1974
  • the Control of Substances Hazardous to Health Regulations (COSHH) 2002 (as amended in 2004
  • Regulation (EC)1272/2008 on classification, labelling and packaging of substances and mixtures. It is known by its abbreviated form: 'the CLP Regulation' or 'CLP'. Adjuvant products come under the definition of 'general preparations' and must be classified and labelled in accordance with CLP. You should provide details of proposed classification and associated labelling when you submit your application

Twin packs

When an adjuvant is supplied and marketed together with a PPP for mixing before use, known as a 'twin-pack', it is considered to be part of the authorised PPP.

Whether or not that adjuvant is on the official list, the plant protection product/adjuvant combination must be considered by HSE for safety and efficacy as part of an application for an authorisation of the PPP.

Is this page useful?

Updated 2024-07-15