Physical and Chemical Properties

Identity and physical and chemical properties of the active substance and plant protection product

This guidance is for applicants on the requirements for the chemical and physical properties of active substances and products which apply under Regulation (EC) No 1107/2009 (there are data requirements under the regulation).

Before you submit your application you can check that it is complete using the Chemistry section of the common omissions checklist.

Active substance

For each source of an active substance a technical specification is required.

A 'source' refers to a technical material manufactured by a specific process in a particular location and is described by an individual technical specification and its supporting data package.

A number of sources may be authorised for an individual active substance based on different supporting data packages. In addition, a number of sources of an active substance may be authorised in a product.

All technical specifications must be supported by batch data and validated methods of analysis so that HSE can ensure the technical specification reflects the minimum level of the active substance and the maximum levels of impurities found in routine manufacturing.

The technical specification should contain the following:

  • minimum content (g/kg) of the pure active substance
  • the nature and maximum levels (g/kg) of all impurities, isomers or additives present at or greater than 1 g/kg of the total content of the active substance (ie those impurities deemed significant)
  • the nature and maximum levels (g/kg) for toxicologically relevant impurities even if present at less than 1 g/kg

What constitutes a change to the technical specification?

The technical specification is dependent on many factors, including the manufacturing location, manufacturing process, and scale of manufacture. If any of these factors change, then it is necessary to provide data to either support a revised specification or a reasoned case as to why data are not required.

If a specification is different to that which is authorised, an assessment of technical equivalence to the reference specification (usually that considered for approval of the active) is required.

Pesticide active substance source changes: technical equivalence

How do we assess technical equivalence?

Technical equivalence is determined in accordance with the Guidance document on the assessment of the equivalence of technical materials of substance regulated under Regulation (EC) No 1107/2009 (SANCO 10597/2003). The technical equivalence assessment is formalised in the completion of an equivalence report.

Plant protection product

The details of a product consist of the technical specification and the product 'recipe', this consists of:

  • nominal target content of the pure active substance, with acceptable tolerance limits in line with Food and Agriculture Organisation of the UN (FAO) guidance Manual on development and use of FAO and WHO specifications for pesticides, 2016
  • chemical name, trade name and/or CAS number, structure and quantity of all other components (the co-formulants) in the product (please note the unacceptable co-formulants register)
  • The content of pure active substance and levels of co-formulants should be given in % w/w and either g/kg or g/L depending on the physical state of the product.┬áThe density of liquid products used to calculate the % w/w values should also be given.

Further guidance on the chemical and physical data required to support the registration/authorisation of a product are available in this Draft Guidance document for the generation and evaluation of data on the physical, chemical and technical properties of plant protection products. This is a draft document and contains references to EU legislation and Commission Communications. Whilst these legislative references have changed this does not result in any substantive changes to the technical guidance outlined.

For authorisations for seed treatments see further guidance on the HSE requirements to address chemistry assessments.

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Updated 2024-04-30