Pyrethroids

Synthetic insecticides derived from pyrethrin — highly toxic to aquatic insects and fish at very low concentrations (nanograms per litre).

Pyrethroids are a large class of synthetic insecticides based on the structure of naturally occurring pyrethrins. They are lipophilic (fat-soluble) and highly toxic to aquatic invertebrates and fish at very low concentrations. EU priority substance pyrethroids in Directive (EU) 2026/805: Bifenthrin (No.50), Cypermethrin (No.41), Deltamethrin (No.55), Esfenvalerate (No.58), and Permethrin (No.64). AA-EQS values are in the nanogram range (e.g., Deltamethrin inland: 0.0017 ng/L).

Legal reference

Directive (EU) 2026/805 Annex VI