The UK Technical Advisory Group (UKTAG) has commissioned a programme of work to derive Environmental Quality Standards (EQSs) for substances falling under Annex VIII of the Water Framework Directive (WFD). This report proposes predicted no-effect concentrations (PNECs) for permethrin using the methodology described in Annex V of the Directive. There are existing EQSs for permethrin, but they were derived using a method not considered to comply with the requirements of Annex V and so cannot be used to derive Annex VIII EQSs.
Proposed EQS for Water Framework Directive Annex VIII substances: permethrin (For consultation)
The PNECs described in this report are based on a technical assessment of the available ecotoxicity data for permethrin, along with any data that relate impacts under field conditions to exposure concentrations. The data have been subjected to rigorous quality assessment such that decisions are based only on scientifically sound data. Following consultation with an independent peer review group, critical data have been identified and assessment factors selected in accordance with the guidance given in Annex V. This report is an update of report Number SCHO0407BLWF-E-E ‘Proposed EQSs for Water Directive Annex VIII substances: Permethrin’ produced in 2007 as part of a programme of work commissioned by the UK Technical Advisory Group (UKTAG) to derive Environmental Quality Standards (EQSs) for substances falling under Annex VIII of the Water Framework Directive (WFD). The original report proposed PNECs derived according to the Annex V methodology but because of a lack of certain data, large assessment factors were used in their derivation. This led to the UKTAG concluding that the values were unsuitable for use as EQSs since they were subject to excessive uncertainty, but that this uncertainty may be reduced by appropriate additional ecotoxicity testing . Consequently an ecotoxicity study on the alga Pseudokirchneriella subcapitata (Environment Agency 2008) was commissioned with the aim of reducing the data gap, assessment factors and ultimately the uncertainty in the PNEC values . This report incorporates the results of this study and PNECs are re-visited using the more complete dataset. It should be noted that no additional review of any other data/literature that may have been published since the original 2007 report has been made.
Where possible, PNECs have been derived for freshwater and saltwater environments, and for long-term/continuous exposure and short-term/transient exposure. If they were to be adopted as EQSs, the long-term PNEC would normally be expressed as an annual average concentration and the short-term PNEC as a 95th percentile concentration. The feasibility of implementing these PNECs as EQSs has not been considered at this stage. However, this would be an essential step before a regulatory EQS can be recommended.