Permethrin | |
---|---|
3-Phenoxybenzyl |
|
Identifiers | |
CAS number | 52645-53-1 |
PubChem | 40326 |
ChemSpider | 36845 |
UNII | 509F88P9SZ |
DrugBank | DB04930 |
KEGG | C14388 |
ChEBI | CHEBI:34911 |
ChEMBL | CHEMBL1525 |
ATC code | P03 ,QP53AC04 |
Jmol-3D images | Image 1 |
|
|
|
|
Properties | |
Molecular formula | C21H20Cl2O3 |
Molar mass | 391.28 g/mol |
Appearance | colourless crystals |
Density | 1.19 g/cm³, solid |
Melting point |
34 °C, 307 K, 93 °F |
Boiling point |
200 °C, 473 K, 392 °F |
Solubility in water | Insoluble (5.5 x 10-3 ppm) |
Hazards | |
MSDS | External MSDS |
Main hazards | Irritating to skin and eyes, damaging to lungs |
Related compounds | |
Related pyrethroids | Bifenthrin Deltamethrin |
(verify) (what is: / ?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
|
Infobox references |
Permethrin is a common synthetic chemical, widely used as an insecticide, acaricide, and insect repellent. It belongs to the family of synthetic chemicals called pyrethroids and functions as a neurotoxin, affecting neuron membranes by prolonging sodium channel activation. It is not known to rapidly harm most mammals or birds, but is dangerously toxic to cats[1][2] and fish. In general, it has a low mammalian toxicity and is poorly absorbed by skin.[3]
In medicine, permethrin is a first-line treatment for scabies; a 5% (w/w) cream is marketed by Johnson & Johnson under the name Lyclear. In nordic countries it is marketed under trade name Nix, often available over the counter.
Contents |
Permethrin is used:
In agriculture, permethrin is mainly used on cotton, wheat, maize, and alfalfa crops. Its use is controversial because, as a broad-spectrum chemical, it kills indiscriminately; as well as the intended pests, it can harm beneficial insects including honey bees, and aquatic life.[4]
Permethrin kills ticks on contact with treated clothing. A method of reducing deer tick populations by treating rodent vectors involves stuffing biodegradable cardboard tubes with permethrin-treated cotton. Mice collect the cotton for lining their nests. Permethrin on the cotton instantly kills any immature ticks that are feeding on the mice. It is important to put the tubes where mice will find them, such as in dense, dark brush, or at the base of a log; mice are unlikely to gather cotton from an open lawn.
Permethrin is used in tropical areas to prevent mosquito-borne disease such as dengue fever and malaria. Mosquito nets used to cover beds may be treated with a solution of permethrin. This increases the effectiveness of the bed net by killing parasitic insects before they are able to find gaps or holes in the net. Military personnel training in malaria-endemic areas may be instructed to treat their uniforms with permethrin, as well. An application should last several washes.
Permethrin is used on humans to eradicate parasites such as head lice and mites responsible for scabies; the common prescription is Permethrin with 5% concentration for scabies, and OTC (over-the-counter) treatment for head lice/crabs is usually permethrin with 1% concentration. However, the British National Formulary states that permethrin has low efficacy in eradicating head lice.
Permethrin is also used in industrial and domestic settings to control pests such as ants and termites.
Permethrin has four stereoisomers (two enantiomeric pairs), arising from the two stereocentres in the cyclopropane ring. The trans enantiomeric pair is known as transpermethrin.
Permethrin acts as a neurotoxin, slowing down the nervous system through binding to sodium channels. This action is negatively correlated to temperature, thus, in general, showing more acute effects on cold-blooded animals (insects, fish, frogs...) over warm-blooded animals (mammals and birds):
Permethrin is listed as a "restricted use" substance by the United States Environmental Protection Agency[6] due to its high toxicity to aquatic organisms.[7]
Due to high toxicity for aquatic life, permethrin and permethrin-contaminated water should be properly disposed of. Degradation is quick and should the chemical be disposed of far from any aquatic life, the negative effects would be minimized. In a non-industrial context, the contaminant may be placed in direct sunlight to induce photodegradation. Contaminated water exposed to direct sunlight will be cleared of the permethrin and any known pollutant subproducts after a few hours.
According to the Connecticut Department of Public Health, permethrin "has low mammalian toxicity, is poorly absorbed through the skin and is rapidly inactivated by the body. Skin reactions have been uncommon."[8]
Excessive exposure to permethrin can cause nausea, headache, muscle weakness, excessive salivation, shortness of breath, and seizures. Worker exposure to the chemical can be monitored by measurement of the urinary metabolites, while severe overdosage may be confirmed by measurement of permethrin in serum or blood plasma.[9]
Permethrin does not present any notable genotoxicity or immunotoxicity in humans and farm animals, but is classified by the United States Environmental Protection Agency (EPA) as a likely human carcinogen, based on reproducible studies in which mice fed permethrin developed liver and lung tumors.[10] Carcinogenic action in nasal mucosal cells due to inhalation exposure is suspected, due to observed genotoxicity in human tissue samples, and in rat livers the evidence of increased pre-neoplastic lesions raises concern over oral exposure.[11][12]
Studies by Bloomquist et al., 2002 [13] suggested a link of permethrin exposure to Parkinson's disease, including very small (per kg.) exposures:
However a more recent 2007 study by the same researcher concluded that there was "little hazard to humans"
A 2006 study in South Africa, found residues of permethrin in breast milk, together with DDT, in an area that experienced DDT treatment for malaria control, as well as the use of pyrethroids in small-scale agriculture.[17]
Permethrin is toxic to cats. Many cats die after being given flea treatments intended for dogs, or by contact with dogs having recently been treated with permethrin.[18]
|
|