SETAC Spotlight: Modified Exposure Studies in Aquatic Risk Assessments: How useful are they?

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SETAC Spotlight: Modified Exposure Studies in Aquatic Risk Assessments: How useful are they?

CEA presented 17 posters and platforms at SETAC Copenhagen in May 2022. Since then we have been showcasing each of these presentations in a series of 'SETAC Spotlight' articles. This week it is:

Modified Exposure Studies in Aquatic Risk Assessments: How useful are they?

Author: Hanna Schuster

Modified exposure studies are included as a refinement option (Tier 2C) for aquatic risk assessments for plant protection products (PPPs) under the current guidance (EFSA 2013). They can be a useful refinement option for scenarios where the predicted exposure profile indicates that exposure will not be continuous, and therefore ecotoxicity endpoints based on constant exposure may be over conservative. The overall aim of modified exposure studies is to more closely align the exposure profiles used in the ecotoxicity study with that predicted by the exposure profiles, such that we are assessing the more realistic risk from the proposed use of the PPP. Although Tier 2C refinements are permitted under the current aquatic guidance, some EU Member States have indicated that they will not readily accept such an approach; for example, the central zone MSs recently concluded that Tier 2C refinements ‘should generally not be supported at zonal level, considering that implementation in ERA is complex and linked to high uncertainties’. No further detail is provided regarding what ‘complexities’ and ‘uncertainties’ are being referred to. 

This poster reviews active substance dossiers submitted and evaluated at the EU level since 2015 (allowing 2 years implementation of the EFSA (2013) guidance) to determine how many substances have attempted to use a modified exposure approach in the risk assessment and, and of those, how many have been successful (and why), and where rejected, the reasons provided by regulators. Where concerns have been raised by regulators, we will discuss ways in which these could be addressed, aiming to conclude whether or not there is still a role for modified exposure studies in PPP aquatic risk assessments. We will also consider the usefulness of modified exposure studies beyond Tier 2C refinements e.g. supporting the use of TWA PECsw by demonstrating no latency of effects and linear reciprocity.

You can download the poster for free.

You can find all of the other posters and platforms that CEA presented at SETAC Copenhagen here. You can also find all of our publications from previous conferences and links to journal articles we have authored on our library page.


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