Reflections on technical issues related to derivation of PFAS Environmental Quality Standards

In 2022, the European Commission (EC) published a proposal for amending the Water Framework Directive (2000/60/EC), the Groundwater Directive (2006/118/EC) and the Environmental Quality Standards Directive (2008/105/EC). The proposal includes an environmental quality standard (EQS-Sum) for both surface water and biota and a groundwater quality standard (GWQS) for the sum of 24 per- and polyfluoroalkyl substances (PFAS-sum). The surface water and groundwater thresholds are set at 4.4 ng/l of PFOA equivalents. In April 2023, the European Parliament requested that in addition to the EQS for the sum of 24 PFAS, an EQS be derived for the total of all PFAS components (PFAS-Total).

This document highlights some of the scientific challenges that surround the proposed PFAS criteria in the proposal, more specifically: i) the selection of the 24 PFAS in PFAS-sum is not well documented and lacks a clear prioritisation method; ii) EQS- and GWQS-values are not clearly derived and lack underlying data; and iii) Many PFAS QS are below achievable limits of detection and/or quantification. Achieving the required detection limits for each of all 24 PFAS substances poses a challenge, especially for longer-chained PFAS compounds. Demonstrating compliance with the EQS / GWQS will be strongly dependent upon the methodology of how non-detects are treated, given the currently achievable detection limits and certified analytical methods.