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===Personal healthcare ===
===Personal healthcare ===
Permethrin is used on humans to eradicate parasites such as [[head lice]] or mites responsible for [[scabies]] and as a pest-repellent clothing treatment. Permethrin is more effective in reducing itch persistence than [[crotamiton]] or [[lindane]].<ref>[http://summaries.cochrane.org/CD000320/interventions-for-treating-scabies Interventions for treating scabies] at the [[Cochrane review]]</ref> The common prescription is a 5% concentration of permethrin for scabies and a 1% concentration for the over-the-counter (OTC) treatment for head lice or crabs. Pharmaceutical grade permethrin 99% is differentiated from pesticide grade 94% by a higher purity, well specified impurities, and lower content of the toxic CIS component at 25% as opposed to 40% in the pesticide grade. Pharmaceutical grade permethrin is offered commercially by companies like [[VAV Life Sciences]], [[Dow Chemical Company]] etc. and used extensively by agencies working in forest areas such as the US Army.<ref name=Stromdahl>{{ cite web |author=Ellen Stromdahl |date=undated |title=DOD Efforts in Tick Surveillance and Preventing Tick-Borne Disease in the US |publisher=U. S. Army Public Health Command (Provisional) |url=http://www.epa.gov/pesp/events/ticks/6-3%20Ellen%20Stromdahl.pdf}}</ref>
Permethrin is used on humans to eradicate parasites such as [[head lice]] or mites responsible for [[scabies]] and as a pest-repellent clothing treatment. Permethrin is more effective in reducing itch persistence than [[crotamiton]] or [[lindane]].<ref>[http://summaries.cochrane.org/CD000320/interventions-for-treating-scabies Interventions for treating scabies] at the [[Cochrane review]]</ref> The common prescription is a 5% concentration of permethrin for scabies and a 1% concentration for the over-the-counter (OTC) treatment for head lice or "crabs". Pharmaceutical grade permethrin 99% is differentiated from pesticide grade 94% by a higher purity, well specified impurities, and lower content of the toxic CIS component at 25% as opposed to 40% in the pesticide grade. Pharmaceutical grade permethrin is offered commercially by companies like [[VAV Life Sciences]], [[Dow Chemical Company]] etc. and used extensively by agencies working in forest areas such as the US Army.<ref name=Stromdahl>{{ cite web |author=Ellen Stromdahl |date=undated |title=DOD Efforts in Tick Surveillance and Preventing Tick-Borne Disease in the US |publisher=U. S. Army Public Health Command (Provisional) |url=http://www.epa.gov/pesp/events/ticks/6-3%20Ellen%20Stromdahl.pdf}}</ref>


Permethrin is also used in industrial and domestic settings to control pests such as [[ant]]s and [[termite]]s. It may be incorporated in formulations of wood preservative.<ref>[http://www.birdbrand.co.uk/acatalog/Wood_Preservatives.html See entry for Complete Wood Preservative]</ref>
Permethrin is also used in industrial and domestic settings to control pests such as [[ant]]s and [[termite]]s. It may be incorporated in formulations of wood preservative.<ref>[http://www.birdbrand.co.uk/acatalog/Wood_Preservatives.html See entry for Complete Wood Preservative]</ref>

Revision as of 20:35, 16 March 2014

Permethrin
Chemical structure of permethrin
Names
IUPAC name
3-Phenoxybenzyl (1RS)-cis,trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.052.771 Edit this at Wikidata
KEGG
UNII
  • InChI=1S/C21H20Cl2O3/c1-21(2)17(12-18(22)23)19(21)20(24)25-13-14-7-6-10-16(11-14)26-15-8-4-3-5-9-15/h3-12,17,19H,13H2,1-2H3 checkY
    Key: RLLPVAHGXHCWKJ-UHFFFAOYSA-N checkY
  • InChI=1/C21H20Cl2O3/c1-21(2)17(12-18(22)23)19(21)20(24)25-13-14-7-6-10-16(11-14)26-15-8-4-3-5-9-15/h3-12,17,19H,13H2,1-2H3
    Key: RLLPVAHGXHCWKJ-UHFFFAOYAS
  • Cl/C(Cl)=C/C3C(C(=O)OCc2cccc(Oc1ccccc1)c2)C3(C)C
Properties
C21H20Cl2O3
Molar mass 391.29 g·mol−1
Appearance Colorless crystals
Density 1.19 g/cm³, solid
Melting point 34 °C (93 °F; 307 K)
Boiling point 200 °C (392 °F; 473 K)
5.5 x 10−3 ppm
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Irritating to skin and eyes,
damaging to lungs
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)

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 and North America, it is marketed under trade name Nix, often available over the counter.

Uses

Permethrin is used:

  • as an insecticide
    • in agriculture, to protect crops
    • in agriculture, to kill livestock parasites
    • for industrial/domestic insect control
  • as an insect repellent or insect screen
    • in timber treatment
    • as a personal protective measure (cloth impregnant, used primarily for US military uniforms and mosquito nets)
    • in pet flea preventative collars or treatment.

Pest control

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.

Personal healthcare

Permethrin is used on humans to eradicate parasites such as head lice or mites responsible for scabies and as a pest-repellent clothing treatment. Permethrin is more effective in reducing itch persistence than crotamiton or lindane.[5] The common prescription is a 5% concentration of permethrin for scabies and a 1% concentration for the over-the-counter (OTC) treatment for head lice or "crabs". Pharmaceutical grade permethrin 99% is differentiated from pesticide grade 94% by a higher purity, well specified impurities, and lower content of the toxic CIS component at 25% as opposed to 40% in the pesticide grade. Pharmaceutical grade permethrin is offered commercially by companies like VAV Life Sciences, Dow Chemical Company etc. and used extensively by agencies working in forest areas such as the US Army.[6]

Permethrin is also used in industrial and domestic settings to control pests such as ants and termites. It may be incorporated in formulations of wood preservative.[7]

Military use

In order to better protect soldiers from the risk and annoyance of biting insects, the US[8] and British[citation needed] armies are treating all new uniforms with permethrin.

Stereochemistry

Permethrin has four stereoisomers (two enantiomeric pairs), arising from the two stereocentres in the cyclopropane ring. The trans enantiomeric pair is known as transpermethrin.

  • (1S)-trans-acid moiety
    (1S)-trans-acid moiety
  • one cis enantiomer
    one cis enantiomer
  • the other cis enantiomer
    the other cis enantiomer

Toxicology and safety

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 extremely toxic to fish and aquatic life in general, so extreme care must be taken when using products containing permethrin near water sources.
  • Permethrin is also highly toxic to cats, and flea and tick-repellent formulas intended and labeled for (the more resistant) dogs may contain permethrin and cause feline permethrin toxicosis in cats.[9]
  • Very high doses will have tangible neurotoxic effects on mammals and birds, including human beings.

Permethrin is listed as a "restricted use" substance by the United States Environmental Protection Agency[10] due to its high toxicity to aquatic organisms.[11]

Due to high toxicity for aquatic life, permethrin and permethrin-contaminated water should be properly disposed. Permethrin is quite stable, having a half life of 51–71 days in an aqueous environment exposed to light. It is also highly persistent in soil.[12]

Human exposure

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."[13]

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.[14]

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.[15] 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.[16][17]

Studies by Bloomquist et al., 2002[18] suggested a link of permethrin exposure to Parkinson's disease, including very small (per kg.) exposures:

2002 study – "Our studies have documented low-dose effects of permethrin, doses below one-one thousandth of a lethal dose for a mouse, with effects on those brain pathways [that are] involved in Parkinson's Disease [...] We have found effects consistent with a pre-parkinsonsian condition, but not yet full-blown parkinsonism." [19][20]

However a more recent 2007 study by the same researcher concluded that there was "little hazard to humans"

2007 study – "long-term, low-dose exposure to permethrin alone did not cause signs of neurotoxicity to striatal dopaminergic neural terminals, or enhance the effects of MPTP. We conclude that, under typical use conditions, permethrin poses little Parkinsonian hazard to humans, including when impregnated into clothing for control of biting flies"[21]

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.[22]

Domestic animals

Pesticide grade 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.[23] Only the less toxic human, pharmaceutical grade permethrin with well defined impurities and a reduced CIS:TRANS ratio is considered safe for pet use.[24]

See also

References

  1. ^ "Permethrin Hazards For Cats". ASPCA National Animal Poison Control Center.
  2. ^ Franny Syufy. "Cat Flea Control Products Warning". About.com.
  3. ^ "Permethrin". Pmep.cce.cornell.edu. 16 April 1986. Retrieved 5 January 2011.
  4. ^ R. H. Ian (1989). "Aquatic organisms and pyrethroids". Pesticide Science. 27 (4): 429–457. doi:10.1002/ps.2780270408.
  5. ^ Interventions for treating scabies at the Cochrane review
  6. ^ Ellen Stromdahl (undated). "DOD Efforts in Tick Surveillance and Preventing Tick-Borne Disease in the US" (PDF). U. S. Army Public Health Command (Provisional). {{cite web}}: Check date values in: |date= (help)
  7. ^ See entry for Complete Wood Preservative
  8. ^ Insect-repelling ACUs now available to all Soldiers, United States Army
  9. ^ "report "Cats 'killed by flea treatment'"". BBC News. 10 November 2007. Retrieved 5 January 2011.
  10. ^ Environmental Protection Agency. "Restricted Use Products (RUP) Report: Six Month Summary List". Retrieved 1 December 2009. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  11. ^ Environmental Protection Agency. "Permethrin Facts (RED Fact Sheet)". Retrieved 2 September 2011. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  12. ^ "Environmental Fate of Permethrin" (PDF).
  13. ^ Kirby C. Stafford III (February 1999). "Tick Bite Prevention". Connecticut Department of Public Health.
  14. ^ R. Baselt, Disposition of Toxic Drugs and Chemicals in Man, 8th edition, Biomedical Publications, Foster City, CA, 2008, pp. 1215–1216.
  15. ^ Permethrin Facts, US EPA, June 2006.
  16. ^ M. Tisch, P. Schmezer, M. Faulde, A. Groh and H. Maier (2002). "Genotoxicity studies on permethrin, DEET and diazinon in primary human nasal mucosal cells". European Archives of Oto-Rhino-Laryngology. 259 (3): 150–153. doi:10.1007/s004050100406.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  17. ^ K. Hakoi, R. Cabral, T. Hoshiya, R. Hasegawa, T. Shirai and N. Ito (1992). "Analysis of carcinogenic activity of some pesticides in a medium-term liver bioassay in the rat". Teratogenesis, Carcinogenesis, and Mutagenesis. 12 (6): 269–276. doi:10.1002/tcm.1770120605.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  18. ^ Attention: This template ({{cite pmid}}) is deprecated. To cite the publication identified by PMID 12428726, please use {{cite journal}} with |pmid=12428726 instead.
  19. ^ [1] BBC News, March 2006.
  20. ^ [2] Virginia Tech, March 2003.
  21. ^ Kou, J.; Bloomquist, J. R. (2007). "Neurotoxicity in murine striatal dopaminergic pathways following long-term application of low doses of permethrin and MPTP". Toxicol Lett. 171 (3): 154–161. doi:10.1016/j.toxlet.2007.05.005. PMID 17597311.
  22. ^ Bouwman, H.; Sereda, B.; Meinhardt, H. M. (2006). "Simultaneous presence of DDT and pyrethroid residues in human breast milk from a malaria-endemic area in South Africa". Environmental Pollution. 144 (3): 902–917. doi:10.1016/j.envpol.2006.02.002. PMID 16564119.
  23. ^ Linnett, P.-J. (2008). "Permethrin toxicosis in cats". Australian Veterinary Journal. 86 (1–2): 32–35. doi:10.1111/j.1751-0813.2007.00198.x. PMID 18271821.
  24. ^ PERMETHRIN SPOT-ON TOXICOSES IN CATS, Jill A. Richardson, DVM ASPCA Animal Poison Control Center, Urbana, IL, USA

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