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

SCHEER WG on Water Framework Directive
SCHEER members: Marian Scott (Chair), Marco Vighi (Rapporteur), Thomas Backhaus, Teresa Borges, Peter Hoet, Pim de Voogt
External experts: Andrew Johnson, Jan Linders
Contact:SANTE-C2-SCHEERec [dot] europa [dot] eu (SANTE-C2-SCHEER[at]ec[dot]europa[dot]eu)
On request from: European Commission
Adopted on: 25 March 2022

The dossier on Environmental Quality Standards for “Thiamethoxam” was reviewed by the SCHEER according to the general mandate on EQS dossiers. The dossier also included two specific questions for thiamethoxam.

The SCHEER endorses the MAC-QS_fw,eco = 0.55 µg L^-1, derived with a deterministic procedure and the MAC-QS_fw,eco = 0.77 µg L^-1, derived with a probabilistic procedure.

For saltwater, the SCHEER endorses the deterministic MAC_sw,eco = 0.0055 µg L^-1 and the probabilistic MAC_{sw, eco} = 0.0077 µg L^-1.

The SCHEER endorses the AA-QS_fw,eco = 0.043 µg L^-1, derived with a deterministic procedure. The probabilistic procedure is not applied due to the scarcity of data.

In a mesocosm study, a NOEC of 0.3 µg L^-1 was observed. The dossier proposes an AF of 3 to be applied to the mesocosm NOEC. It is the opinion of the SCHEER that there are not sufficient reasons to support this reduction of the AF. Therefore, the default AF of 5 should be applied. The SCHEER proposes a mesocosm-based AA-QS_fw,eco = 0.06 µg L^-1, instead of 0.1, proposed in the dossier.

For saltwater, the SCHEER endorses the deterministic AA-QS_sw,eco = 0.0043 µg L^-1.

The SCHEER agrees with the decision of not deriving an EQS for sediment and for secondary poisoning.

For human health, the SCHEER endorses a QS_biota,hh = 0.74 mg kg^-1 and the adoption of the general drinking water standard for pesticides (0.1 µg L^-1).

Keywords:

pesticides, neonicotinoid, thiamethoxam, 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", Thiamethoxam, 25 March 2022.