Introduction of DROPLET version 1.3.2 in the national authorisation procedure

The DROPLET model is used within the risk assessment to evaluate whether the active substance exceeds the drinking water limit (0.1 μg/L) at the abstraction points of surface water intended for drinking water production.

DROPLET is a pre-registration model, which is used in the assessment of the first product based on an active substance that is new to the Netherlands, and any other substance assessments in the first 3 years from the first authorisation of the active substance in question in the Netherlands. After this period, the assessment will be done on the basis of monitoring data. For more details on the assessment methodology see the our Evaluation Manual Chapter 6 Fate and behaviour in water, NL Part, section 2.3.2 and Appendix 3.

Based on model calculations of the FOCUS surface water model (FOCUS D3 ditch scenario using Dutch drift values), downstream concentrations in surface water abstraction points for the production of drinking water are calculated using DROPLET. Due to a new release of the FOCUS surface water models (e.g. FOCUS SWASH 5.3), it was necessary to adjust DROPLET so that the model results of the FOCUS surface water models can be used by DROPLET. In the new version 1.3.2 of DROPLET, the necessary technical adjustments have been made. No changes have been made to calculations performed by DROPLET. Because the new FOCUS surface water models have changed in terms of content, an impact analysis has been carried out. Based on this impact analysis, it was concluded that the use of the new DROPLET version (1.3.2) has no effect on the conclusion of the assessment with regard to the drinking water criterion for the Netherlands.

Since the current version of DROPLET (version 1.2) only works on Windows 7, an operating system that is no longer supported by Microsoft, it is necessary to have the new version of DROPLET take effect immediately. For ongoing applications for authorisation of plant protection products, the assessment provided by the applicant will be repeated by the Ctgb with the new version of DROPLET.

The Dutch National addendum template Part B Sectie 8 Environmental Fate has been adapted to reflect this change.