A pyrethroid insecticide and modulator of NaVs; delays channel deactivation in cockroach giant axons at 1 μM; 100-fold more potent at insect than rat NaV1.8 channels expressed in Xenopus oocytes; decreases egg production by and is lethal to mosquitos (LC50 = 0.01%); induces production of ROS, lipid peroxidation, and apoptosis in rat primary Leydig cells; increases levels of the hepatic enzymes ALT and AST and induces hepatocyte apoptosis as well as emphysema and lung hyperplasia in mice,