Resmethrin is a type I pyrethroid insecticide. Pyrethroids are synthetic versions of a natural insecticide produced by chrysanthemum flowers.
Although pyrethroids are among the least toxic insecticides, they are nerve poisons. They act upon the sodium ion channels in nerve cell membranes.
The pesticide containing resmethrin being used in NY City is called Scourge (TM). It is 18% resmethrin, 54% piperonyl butoxide and 28% inert ingredients. Piperonyl butoxide makes the pesticide more effective by preventing insects from detoxifying resmethrin.
Manufacturers are not required to disclose the inert ingredients, although they may be toxic also.
Inhaling pyrethroid insecticides can cause coughing, wheezing, shortness of breath, runny or stuffy nose, chest pain, or difficulty breathing.
Skin contact can cause a rash, itching, or blisters.
Piperonyl butoxide can cause skin and eye irritation. All the health effects of this chemical have not been fully researched.
Rats fed high doses (1,000 milligrams per kilogram of body weight or mg/kg) of pyrethrins (natural versions of pyrethroids) showed liver damage. There is also evidence that pyrethroids can harm the thyroid.
Piperonyl butoxide has been classified by the Environmental Protection Agency as a possible human carcinogen.
Resmethrin is not very toxic to mammals, but it is highly toxic to bees and fish.
The half-life of resmethrin in soil is estimated to be 30 days, but varies depending on the type of soil.
Its half-life in water is estimated to be 36 days.
SCOURGE is the brand name of the resmethrin product that was sprayed on New York. The label of this pesticide consists of three parts:
SCOURGE label, part 1
SCOURGE label, part 2
SCOURGE label, part 3