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

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
Contact:SANTE-SCHEERec [dot] europa [dot] eu (SANTE-SCHEER[at]ec[dot]europa[dot]eu)
On request from: European Commission
Adopted on: 13 October 2022

The dossier on Environmental Quality Standards for “Hexachlorobenzene” is reviewed by the SCHEER according to the general mandate on EQS dossiers.

The proposed dossier is a revision of a previous EQS dossier (2015) based on recent data and the procedure proposed in the new EQS Technical Guidance (2018). However, several sections of the dossier refer to old technical documents (2003, 2004). It is the opinion of the SHEER that all the procedures must be updated, in accord with the 2018 EQS Technical Guidance.

Moreover, all effect data used are older than 2005. This seems in contradiction with the statements of the dossier.

An AA-QS_{fw, eco} =0.013 μg L^-1, derived with the deterministic procedure is endorsed by the SCHEER.

The same value is proposed as AA-QS_sw,eco. The SCHEER does not agree with the proposal.

The QS_{SPM.freshwater} and QS_{SPM.saltwater} are calculated using a formula taken from an old (2004) EQS Manual. The SCHEER suggests revising using the more recent guidance.

A MAC-QS_{fw, eco} =0.05 μg L^-1, derived with the deterministic procedure by applying an AF of 100 is not endorsed by the SCHEER. It is the opinion of the SCHEER that an AF of 10 is more appropriate, leading to a MAC-QS_{fw, eco} = 0.5 μg L-1.

The QS_sediment is calculated using the equilibrium partitioning method with procedures taken from an old (2004) EQS Manual. The SCHEER suggests revising using the more recent guidance.

The SCHEER endorses the procedure and calculation of the QS_biota,water of 27 μg L^-1.

The QS_{biota, hh food} = 19.63 μg.kg^-1_biota (rounded to QS_{biota, hh food} = 20 μg.kg^-1_biota) and the QS_{water, hh food} = 0.0525 ng L^-1 (rounded to QS_{water, hh food} = 0.053 ng L^-1) are endorsed by the SCHEER.

For the exposure via drinking water, the SCHEER agrees with using the general drinking water standard for pesticides (QS_dw,hh = 0.1 μg L^-1) since HCB is a fungicide, although no longer in commercial use.

Although some QSs are not endorsed by the SCHEER, it is likely that the most critical EQS is the QS_{water, hh water} = 0.053 ng L^-1.

Keywords:

Hexachlorobenzene, HCB, 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, Hexachlorobenzene, 13 October 2022.