ABSTRACT

In designing rened exposure studies with standard or additional species, parameters like “mode of action,” time to onset of effect, and the appropriateness of using sensitive life stages should be considered. To adopt a realistic worst-case scenario, the rened exposure regime tested should be guided by relevant exposure predictions for the intended agricultural uses (e.g., as deduced from FOCUS [Forum for the Co-ordination of Pesticide Fate Models and Their Use] surface water scenarios or from national exposure scenarios but based on the most representative generalized

exposure prole as described in Chapter 4). The recommendation to use generalized exposure proles prevents the use of specic scenarios that may change over time or location of product use, which could lead to additional and possibly unnecessary work.