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SCHEER - Scientific Opinion on "Draft Environmental Quality Standards for Priority Substances under the Water Framework Directive" - Diclofenac

Final Opinion


SCHEER WG on Water Framework Directive
SCHEER members: Marian Scott (Chair), Marco Vighi (Rapporteur), Thomas Backhaus, Teresa Borges, Peter Hoet, Pim de Voogt, Rodica Mariana Ion
External experts: Andrew Johnson, Jan Linders
On request from: European Commission
Adopted on: 6 May 2022

For the draft dossier on Environmental Quality Standards on diclofenac, the SCHEER offers the following opinions:

The selected diclofenac MAC QS presented in the dossier does not seem to have been correctly identified from the ecotoxicity dataset and the SCHEER proposes a MAC QSfw eco of 246 μg L- 1 (rounded to 250 μg L- 1) and a MAC QSsw eco of 29 μg L-1 as alternatives. Regarding deriving the AA-QS, individually neither the deterministic approach, using the mesocosm study by Joachim et al (2021), nor the probabilistic approach using the SSD could be said to be satisfactory on their own (study reliability and poor fit of curve). But by taking a weight of evidence approach including considering the NOEC of the community response in the mesocosm study and utilising the bulk of chronic data provided, the SCHEER supports the AA-QSfw eco of 0.04 μg L-1 and AA-QSsw eco of 0.004 μg L-1.

The SCHEER accepts there is no necessity to derive a benthic organism related QS given its high solubility. Given the widespread and serious population effects of diclofenac on Asian vultures (Gyps bengalensis), the dossier uses data from these birds to derive QSbiota sec pois of 1.16 μg kg-1 (rounded to 1.2 μg kg-1) for mussels and using a BAF of 216 L kg-1 this translated to a QSbiota sec pois of 0.0054 μg L-1. Given the starting point of an ADI provided by EMA, a QS to protect human health with respect to fish consumption of QSbiota hh of 61.35 μg kg-1biota ww (rounded 61 μg kg-1) was calculated. To protect human health from drinking using the same ADI led to a QSdw hh of 3.5 μg L-1 being offered. Both of these human health QS are endorsed by the SCHEER.

The lowest EQS value is the AA-QSsw eco of 4 ng L-1, however, the QSbiota sec pois of 5.4 ng L-1 would be more difficult to achieve in fresh water and therefore could be considered the most critical.


Diclofenac, Water Framework Directive, environmental quality standards

Opinion to be cited as:

SCHEER (Scientific Committee on Health, Environmental and Emerging Risks), Final Opinion on Draft Environmental Quality Standards for Priority Substances under the Water Framework Directive - diclofenac, 2 August 2022.


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