EFSA: Statement on the FERA guidance proposal (2012) on how aged sorption studies for pesticides should be conducted, analysed and used in regulatory assessments

The European Food Safety Authority (EFSA) Panel on Plant Protection Products (PPR) prepared a scientific opinion on the Food and Environment Research Agency (FERA) guidance proposal ‘Guidance on how aged sorption studies for pesticides should be conducted, analysed and used in regulatory assessments’ (2012).

The potential for the strength of soil sorption of a substance to increase over time (‘aged sorption’) is one of the phenomenon considered by applicants and notifiers when developing higher-tier approaches for leaching risk assessment. However, the procedures used to derive parameters to allow the inclusion of aged sorption as a higher-tier refinement for regulatory submissions are currently very uncertain, as demonstrated by the variety of different approaches employed for different substances.

FERA draft guidance was drafted in that context, based on the FOCUS (2009) guidance.

The review of the draft guidance by the Panel revealed that the experimental and modelling approaches described are reasonable compromises between the required effort and what is desirable from a theoretical point of view. However, the Panel has concerns about the interpretation of the experiments and how the results of the experiments should be used in the leaching assessment. The Panel investigated options for improvement, but could not complete its evaluation on these two topics because underlying data to test these options were not made available to the Panel. For this reason, the Panel prepared a statement instead of a scientific opinion. Therefore, the Panel cannot recommend the use of the guidance for the time being.

The Panel recommends an update of the current FERA draft guidance document, taking into account the conclusions and recommendations provided in its statement.

The Panel noted that the draft guidance document did not systematically review uncertainties arising from the use of aged sorption data in regulatory leaching assessments. Uncertainties may result from, for example, the experimental procedure (extraction procedures), the conceptual model and the quality of the fitted parameters. It is recommended that a systematic review of uncertainties is carried out when updating the draft guidance document.

This updated guidance document could be resubmitted to the Panel, together with supporting data, so that the Panel can finalise its review.