Transpiration Stream Concentration Factor (TSCF) describes if a compound can in principle be taken up via the plant root system and thus is removed from the soil. It is used as a parameter in the EU regulatory environmental fate modelling according to FOCUS Groundwater to refine ground water leaching assessment. Recent EFSA guidance proposes a default uptake factor of 0 and suggests TSCF values from “uptake experiments with appropriate and agreed set-up to be developed” as a possible refinement option. To address this need, a novel study design has been developed using a hydroponic system to experimentally determine the capability of plants to take up specific compounds from soil pore water. To validate this study design, ten laboratory organizations with different levels of experience with uptake testing participated in a ring test and studied uptake of [14C]-1,2,4-triazole by wheat plants. Afterwards, uptake of ten radiolabelled chemicals with various properties by potato, tomato or wheat plants was investigated in two laboratories. The detailed experimental design and results will be shared in this presentation. The current study design is being evaluated during the course of the OECD process to determine if it can produce reliable data on plant uptake to be used as input for refined exposure modelling. An explicit guidance, on how to integrate the requested study design into the regulatory process is aimed to be developed based on the outcome of the final OECD test guideline.

Development of plant uptake factor study for regulatory environmental fate modeling

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.