Environmental fate and behaviour in pesticide registration in Great Britain and Northern Ireland – An applicant's guide

When you are applying for pesticide registration in Great Britain or Northern Ireland you need to provide a full consideration of the environmental fate and behaviour of the active substance and product.

The key considerations are covered in Environmental fate and behaviour: Information for pesticide registration. Please refer to this page for an overview of all the web pages available for use for pesticide registration in Great Britain and Northern Ireland.

Additional useful information is provided below.

Information available on other webpages (summaries of each page are included below)

If you require further guidance please contact HSE.

Regulations and data requirements for pesticide product registration

Environmental fate and behaviour data requirements are set under Regulation No (EC) 1107/2009:

You must follow the regulations above and to consider all the available guidance.

Product authorisation is based on guidance in place at the time of submission. 

Regulations and data requirements for pesticide active substances

Environmental fate and behaviour data requirements under Regulation No (EC)1107/2009 are as follows:

Additional guidance has come into force since the Test methods and guidance document 2013 linked above. Some of the key guidance for Environmental fate and behaviour are:

You must follow the regulations above and are advised to consider all the available guidance.

Active substance approval is based on guidance in place at the time of submission. 

Plant protection products (PPP)/pesticide exposure assessments

Data on the formulation, active substances and metabolites must be good enough to:

  • estimate the predicted environmental concentrations (PEC) in soil, groundwater, surface water, sediment and air
  • identify measures necessary to minimise contamination of the environment
  • conclude an authorisation (or refusal) of the PPP
  • specify relevant risk and safety phrases, which must be included on product labels

It is the applicant's responsibility to meet all aspects of the product data requirements and show that risks are acceptable.

Guidance is provided on how to conduct assessment in each environmental compartment:

Guidance for assessments for surface water and groundwater following use of products on hard surfaces is provided in HardSPEC: Surface and ground water exposure model for pesticide registration in GB and NI.

You should ensure that the approach taken encompasses GB/NI geoclimatic situation and agricultural practices.

Endpoints for use in plant protection products/pesticide exposure assessments

Show all endpoints used in your assessments.

The endpoints for the approved active substances are the endpoints for use in GB/NI assessments.  Note that over time the active substance endpoints for GB and NI may diverge as a result of the separate active substance approval procedures for GB and EU (relevant for NI).

Note that for GB/NI assessments water dissipation T 50 values are used for spray drift exposure assessments.

Use of new guidance with regards to the generation of active substance endpoints, should not occur at the product authorisation stage.  Use of new guidance influencing the derivation of endpoints occurs at the time of active substance approval or renewal.  Within GB/NI the endpoints for use in product authorisations are the endpoints from the relevant active substance approval.

If evaluation using agreed end points results in an unacceptable risk assessment, you can seek to amend an endpoint by providing extra data or applying new guidance. You must show that the use of extra data or new guidance is necessary by providing an assessment using the agreed endpoints (or endpoint derived from old guidance) first. You must also add any new data to the existing data, rather than replace the existing data with the new data.

If endpoints from a confirmatory data assessment (that has been finalised by the appropriate procedure for use in Great Britain or Northern Ireland) are available, use these endpoints. An exception exists if assessments using previously agreed endpoints are protective of assessments using the new endpoints and an acceptable assessment with existing agreed endpoints has already been provided.

Where there are multiple potential endpoints for the parent (that is the case for pH dependent degradation), the values to use when modelling the parent may differ from the value to use when modelling the metabolite. Use the approach and endpoints in the active substance assessment, or any post approval assessment. If you use an alternative approach provide robust justification.

Use patterns clearly defined

Provide the following information regarding use pattern:

  • crop type(s)
  • earliest and latest growth stages
  • timings of applications (month/season)
  • number of applications
  • application rate
  • minimum interval between applications
  • application method
  • crop interception

If the use pattern involves additional information which could impact the exposure assessment such as: split doses, banded applications, slow release formulation, explain this clearly and ensure your exposure assessment addresses all relevant aspects of the use pattern.

Modelling outputs

When conducting computer modelling such as FOCUS ground water or higher tier drainflow modelling provide at least an example of the modelling output which shows;

  • the endpoint values used as input parameters
  • the options selected within the model
  • a representative selection of the results

The level of reporting must be sufficient to allow HSE to independently validate your submission, including replicating the modelling where this is considered necessary as part of our assessment.

Multiple crops or use patterns

You should assess environmental exposure based on the worse case use (critical good agricultural practice (GAP)) for multiple uses.  Different crops, or use patterns, may represent the critical GAP for different environmental compartments.

It is your responsibility to demonstrate that the evaluated use is the worse case use for a given environmental compartment.

You must consider at least the following:

  • the crops
  • the growth stage
  • crop interception
  • timing of applications
  • application rate (consider highest individual, and maximum total dose)
  • application methods
  • change in formulation, eg to a slow release formulation
  • all parameters for the exposure calculations relevant to the above parameters, such as the crop interception for a given crop at a given growth stage/at a given time of year

Take note that the worse case use for each compartment can differ.

You may need to assess the highest single application dose and, the multiple total dose pattern* to determine the worse case use.

*either as summed total dose, or multiple doses with shortest interval.

HSE can use one worse case use as a risk envelope if you submit several products containing the same active at once. This will make the assessment more efficient.

Surrogate crops

Provide clear justification for the choice of surrogate crops in modelling. The justification should include a consideration of crop growth habit, crop morphology including rooting depth, as well as critical crop development stages such as emergence and harvest. 

Ecotoxicologically relevant metabolites

For product assessments in GB/NI evaluations are only required in soil, surface water and sediment for metabolites which are deemed ecotoxicologically relevant (as defined as part of the active substance assessment).

Evaluation of all major soil metabolites are required in ground water.

Information available on other webpages

Risk envelopes

Risk envelope is the term used for an authorised product with assessments of higher (or the same) environmental exposure.  Your product use is then said to be within the risk envelope of the existing product. In other words, the previous evaluation proves that the proposed uses for the new product carries acceptable risk.

Compare the critical use pattern(s) of each product for each compartment (PECsoil, PECSw, PECsed, PECgw, PECair).  You can use one product as a risk envelope for the first compartment and other products as a risk envelope for the other compartments.

Risk envelopes can be used when evaluating a single product but with multiple use patterns by identifying the use pattern which sets the risk envelope for all other uses.

For further guidance refer to Risk envelope suitability for pesticide registration in Great Britain and Northern Ireland.

Disposal and transplanting of growing media into soil

Plants grown in organic media within containers can result in transport of plant protection products to soil due to either disposal of growing media, or the transplantation of the container grown plants into the field. There is further information on page Disposal or transplanting of growing media: environmental fate considerations for pesticide registrations in Great Britain and Northern Ireland.

Crop interceptions in orchards, on turf and on asparagus

For most product assessments use the crop interception values relative to the minimum growth stage from EFSA DegT50 guidance (2014).

Further guidance on possible refinements for contact herbicides applied to the floor or orchards, granular products for use on turf, and products for application to asparagus are provided on the page Crop interception standard approach and refinements: pesticide registration in Great Britain and Northern Ireland.

Home garden products

For products to be used in private gardens, homes or allotments please consider the additional advice provided in Garden home and Home garden products: Environmental fate considerations for pesticide registration in Great Britain and Northern Ireland (content will be published early in 2021).

Protected uses products

For products for use within protected environments it is important to clearly define:

  • which type of structures the product is for use in
  • which growing media crops will be grown
  • which, if any, restrictions are applicable to the use of the product

Further information is provided in Protected use products: Environmental fate considerations for pesticide registration in Great Britain and Northern Ireland.

Ornamental crops

For use on ornamental crops, in addition to the standard environmental fate and behaviour considerations, you need to consider what crop grouping your product is likely to be used on and ensure all appropriate information is provided. Further information is provided in Ornamental crops: environmental fate considerations for pesticide registration in Great Britain and Northern Ireland.

Micro-organisms as PPPs

For products containing micro-organisms additional information is available at Environmental safety evaluation of microbial biocontrol agents and Biopesticides.

Environmental fate and behaviour guidance is provided at Micro-organisms, Biopesticides – Environmental fate and behaviour considerations for pesticide registration in Great Britain and Northern Ireland.

Post-harvest treatments

Additional considerations are required for products which are to be used in warehouses or during other post-harvest treatments. Further information is provided in Post-harvest treatments: Environmental fate considerations for pesticide registration in Great Britain and Northern Ireland.


Combined risk assessment

If the product contains multiple active substances, consider a combined risk assessment. For further details refer to Combined risk assessment for pesticide registration in Great Britain and Northern Ireland.

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Updated 2023-11-21