Based on consultation with Member States, EFSA asked the Panel to prepare a revision of theGuidance Document on the persistence of plant protection products in soil (SANCO/9188VI/1997 of12 July 2000) as scientific knowledge in this field has evolved in recent years. Therefore the Paneldeveloped a revised methodology for the assessment of exposure of soil organisms to such products.Based on a previous Opinion of the Panel, this methodology has been developed both for theconcentration in total soil and the concentration in the soil pore water. The goal of the exposureassessment has been chosen to be the 90th percentile of the exposure concentration in the intended areaof use in each of the three regulatory geographical zones (North, Centre, South). The exposureassessmentmethodology is restricted to spray applications to annual crops under conventional orreduced tillage (excluding tillage systems with ridges and furrows). The Panel proposes a tieredapproach. Tier 1 is based on a simple analytical model. Tier 2A is based on simulations withnumerical models. To keep the approach as simple as possible, the Panel based Tiers 1 and 2A foreach regulatory zone on only one scenario each for the concentration in total soil and for that in porewater. These scenarios are to be used for all these annual crops and for all plant protection products ineach regulatory zone. Tiers 2B and 2C are also based on the simple analytical model but in these tiersa specific crop or crop group and an individual plant protection product are considered. Tier 3 is basedon simulations with numerical models but, as in Tiers 2B and 2C, a specific crop or crop group and aspecific plant protection product are considered. All tiers aim to assess the same exposure assessmentgoal. Given the complexity of the calculations in the different tiers, efficient use of this tieredapproach in the regulatory process is impossible without software tools. Therefore the Panelrecommends developing user-friendly software tools for the calculation of the exposure concentrationsin the different tiers.
