July 19, 2021 by Graham Merrington

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We at wca have been working over the last year and a half on the exposure data for some of the Watch List substances under the Water Framework Directive (WFD), including diclofenac, to assess the reliability and representativity of these monitoring data for use in EU-wide risk assessment. We have now published a paper on the (mis)use of these data in the current EQS derivation process under the WFD. The paper is accompanied by all the data (from the EEA databases and from Member State public data repositories) in the online Supplemental Information and you can therefore scrutinise what has been undertaken yourself, in line with the FAIR principles. The uncertainties around the 95^th percentiles of each dataset are presented and how these have been calculated is clearly described. Not surprisingly the data for most of these substances are reflective of ‘analytical method sensitivity’ rather than any ‘measure of the substance in the environment’.

The Watch List data are not always representative of country specific exposures and therefore not EU-wide exposures for some of the substances. This is certainly no criticism of the Member State countries, but rather an issue with how the Watch List data are being processed and used in the current EQS derivation and risk assessment process.

In the paper we propose a way forward to assess the reliability of these datasets and explain why, for some substances, these data are clearly not suitable for evidence-based risk assessment, potentially leading to the adoption of an EU-wide legally based EQS.

As with the previous ET&C article (https://doi.org/10.1002/etc.4987), we welcome open dialogue and discussion on this – so please do, if you have any queries, let us know.