Residues

When assessing residues, the options offered by the risk envelope approach are limited. This is because the assessment is linked to circumstances (indoor or outdoor), application methods and individual crops Moreover, whether MRLs are exceeded must always be determined (MRLs are often set for individual crops).

Risk envelope parameters

The main parameters that determine the risk envelope for residues are the following:

• Dose
• Number of uses
• Interval between uses and between last use and harvest (PHI).

A GAP becomes increasingly critical with higher doses, more uses, shorter intervals between uses and/or shorter PHIs. If multiple parameters differ in terms of criticality, it is usually impossible to identify the most critical GAP based on the GAP parameters.

Risk envelope assessment

An extended authorisation of the use falls within the risk envelope of the existing authorisation if:

• the GAP of the new use is comparable to or less critical than the existing GAP;
• the application methods and conditions are the same;
• extrapolation of residue data is possible according to SANCO 7525/VI/95;
• the MRL calculation based on residue data shows that the MRL for the requested crop is not exceeded.

Within Europe, two zones have been distinguished for residues: Northern Europe and Southern Europe. For seed treatment, use in greenhouses, post-harvest use and treatment of empty storage areas, Europe is not divided into zones, but all of Europe is a single zone. In principle, a full series of trials must be submitted for each zone/use. When one or more zones/conditions are clearly less worst-case than others based on a partial data set, it may be sufficient to submit a full data set for only the more critical conditions. In that case the less critical zones/conditions are covered by the risk envelope.