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

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:

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:

 
Updated 2021-08-10