Scientific Opinion on outline proposals for assessment of exposure of organisms to substances in soil
The European Food Safety Authority (EFSA) asked the Panel to prepare a revision of the Guidance Document on persistence in soil (SANCO/9188VI/1997 of 12 July 2000) as scientific knowledge in this field has evolved in recent years. Therefore the Panel started the development of a revised methodology for the assessment of exposure of soil organisms. Based on a previous opinion of the Panel, the methodology is developed both for the concentration in total soil and the concentration in the soil pore water. The aim of the exposure assessment is the spatial 90th percentile of the exposure concentration (maximum in time) in the intended area of use in each of the three regulatory zones. The assessment of this percentile will include the uncertainty of substance and soil properties. The exposure assessment methodology is a function of (i) the type of crop (annual, pasture, permanent or rice), (ii) the tillage system and (iii) the application technique of the plant protection product. Based on statistical data of EU agricultural practice, priority was given to developing a methodology for spray applications to annual crops under conventional or reduced tillage. The Panel considers a mixing depth of 20 cm appropriate for both conventional and reduced tillage in multi-year exposure calculations. The Panel proposes a tiered exposure assessment approach with four tiers. Tier 1 consists of a simple analytical model.