Permethrin is highly toxic to aquatic species, bees, etc.
Effects on Aquatic Organisms
Permethrin is toxic to fish and should be kept out of all bodies of water (1). It was highly toxic to fish in laboratory tests, but showed low toxicity in field tests (23). Aquatic ecosystems are particularly vulnerable to the impact of permethrin. A fragile balance exists between the quality and quantity of insects and other invertebrates that serve as fish food (2).
The LC50 for rainbow trout is 12.5 micrograms per liter (ug/l) for 24 hours, and 5.4 ug/l for 48 hours (7). The LC50 for 48 hours in bluegill sunfish and salmon is 1.8 ug/l (2). As a group, synthetic pyrethroids were toxic to all estuarine species tested. They had a 96-hour LC50 of less than or equal to 7.8 ug/l (15).
Effects on Other Animals (Nontarget species)
Permethrin is extremely toxic to bees. Severe losses may be expected if bees are present at treatment time, or within a day thereafter (7, 12). Permethrin is also toxic to wildlife (9). It should not be applied, or allowed to drift, to crops or weeds in which active foraging takes place (4).