Mode of Action: Pyrethroids inhibit sodium and potassium conduction in nerve cells and block nerve impulse transmission. Many times pyrethroids are mixed with piperonyl butoxide in formulations.

Immediate Effects: Symptoms similar to DDT poisoning (see organochlorine). T-syndrome: tremors; exaggerated startle response; hyperthermia. CS-syndrome: excessive writhing and salivation; decreased startle response; increase in adrenalin and blood sugar. Other possible effects: convulsions; diarrhea; headache; vomiting; labored breathing; excessive nasal mucous discharge; irritability; sweating; sudden swelling of face, eyelids, lips, mouth, and throat tissues; hay-fever like symptoms; elevated pulse.

Long Term Effects: Suspect mutagens; suspect teratogens; suspect carcinogens; immunotoxins; decreased hormone release from brain; some may be cumulative.

Environmental Effects: Highly toxic to fish, bees, and aquatic arthropods.

Examples of pesticides in this class:

permethrin