Risk envelope suitability for pesticide registration in Great Britain and Northern Ireland
When you are applying for registration of a pesticide in Great Britain/Northern Ireland, then it may be possible to use a currently authorised product as a risk envelope for a proposed new product. This can simplify the environmental exposure assessment. You need to compare the crops, growth stages, application rates, number of applications, and application intervals to demonstrate that the previous assessment is sufficient to address the risks from the new use in each area of the risk assessment.
You need to fully reference any previous products relied upon as a risk envelope as part of your application and you also need to explain the risk envelope approach in each environmental compartment.
- Parameters that need to be considered
- Example of the use of a risk envelope
- Things to look out for when considering a risk envelope
Parameters that need to be considered
The following parameters need to be considered when using the risk envelope approach:
| Parameter | Condition | Comments |
|---|---|---|
Crop |
In most cases, the crop should be identical, or in the same 'primary group' in the crop definition list. |
It can be appropriate to use a risk envelope from another crop for calculation of PECsoil values when you demonstrate that the amount reaching the soil is greater for the previously assessed product. It is more difficult for groundwater and surface water assessments, where individual crops are parameterised in models. Different crops will also be grown on different soils, which can influence vulnerability to drainflow. |
Application rate |
The previously assessed use pattern should have been performed on an identical or higher application rate (g a.s/ha) |
These parameters can interact with substance DT50 values to change the suitability of a product as a risk envelope. For example, if the DT50 value of the active substance is very long, then a lower application rate with a higher number of applications may still be suitable for use as a risk envelope in soil, due to build-up of residues across the applications. Alternatively, if the water phase DT50 value is very short, residues would dissipate between spray applications, meaning a single application results in a higher level of exposure than the multiple application use pattern. You must provide a clear justification to use these types of approaches. |
Number of applications |
The previously assessed use pattern should have an identical or higher number of applications. |
|
Application interval |
The previously assessed use pattern should have an identical or shorter application interval. |
|
BBCH growth stage/ Application window/ Crop interception |
The previously assessed application timing should be similar or occur at a more vulnerable time of year. BBCH growth stages should typically be similar or earlier, however for some crops a late application with regard to BBCH can be worse due to leaf fall. The BBCH growth stages should translate to identical or lower crop interception values than that of the proposed uses of the new product. |
Different application windows can occur at more/less vulnerable times of year from a climatic perspective. For example, the lower tier assessment of drainflow assumes the drainflow period runs from October to April, so an application window coinciding with the drainflow period would be more conservative than an application window outside the drainflow period. |
You need to fully reference any previous products relied upon as a risk envelope as part of your application and you also need to explain the risk envelope approach in each environmental compartment.
Example of the use of a risk envelope
The table below displays the main application parameters of interest for 3 currently approved products containing the hypothetical active substance 'B'. The table includes two products and the representative use from the EU review assessment of substance B.
| Evaluation | Crop | Application rate (g a.s/ha) |
Number of applications | Application interval (days) | BBCH timing | Crop interception (%) |
|---|---|---|---|---|---|---|
| Product X | maize | 175 | 1 | N/A | 10-19 | 25 |
| Product Y | maize | 175 | 2 | 7 | 00-09 | 0 |
| Product Z | maize | 150 | 2 | 7 | 10-09 | 25 |
A new proposed product, Product A, features the following parameters:
| Evaluation | Crop | Application rate (g a.s/ha) |
Number of applications | Application interval (days) | BBCH timing | Crop interception (%) |
|---|---|---|---|---|---|---|
| Product A | maize | 160 | 2 | 7 | 10-19 | 25 |
The following points are important in considering whether a risk envelope is available:
- Product A features applications to the same crop as the previous assessments.
- Product A has the same number of applications as Products Y and Z.
- Product A features a higher application rate than Product Z. Therefore, Product Z may not be appropriate for the risk envelope approach.
- Product X features a higher application rate than the new Product 'A', but only has a single application. Therefore, it may not be appropriate to use Product X as a risk envelope for Product A.
- Product Y features a higher use rate, identical number of applications and interval to the proposed uses of Product A. It also has an earlier BBCH window which translates to lower crop interception.
In this instance, Product Y is sufficient to address this risk of the proposed use, and can therefore provide a risk envelope for Product A.
Things to look out for when considering a risk envelope
When using the risk envelope, you need to be aware of the following possible issues:
- Label amendments/restrictions applied to the previous assessment used as a risk envelope may need to be transferred to the proposed use. To remove label restrictions or buffer zones you will need to provide an environmental exposure and risk assessment in relevant compartments to demonstrate an acceptable risk from the proposed use.
- The previously assessed product may use endpoints derived from new studies. If these studies are data protected, you must have access to the protected studies.
- Assessment of standard spray drift exposure using the Rautmann drift values can return lower PEC values for multiple applications than when considering a single application.
- It is possible to use multiple risk envelopes for one evaluation. For example you may reference to product Y for the soil assessment, but to product V for the surface water spray drift assessment.
- If using the risk envelope approach for two active substances that have previously not been formulated together, please refer to guidance on Combined Risk Assessments for pesticide registration in Great Britain and Northern Ireland.