Malathion

Names
Other names	2-(Dimethoxyphosphinothioylthio) butanedioic acid diethyl ester Malathion Carbofos Maldison Mercaptothion Ortho malathion
IUPAC name Diethyl 2-[(dimethoxyphosphorothioyl)sulfanyl]butanedioate
Chemical and physical data
Formula	C10H19O6PS2
Molar mass	330.358021
3D model (JSmol)	Interactive image
Density	1.23 g/cm3 g/cm3
Boiling point	at 0.7 mmHg
Solubility in water	145 mg/L at 20 °C[1] mg/mL (20 °C)
SMILES O=C(OCC)C(SP(=S)(OC)OC)CC(=O)OCC
InChI InChI=1S/C10H19O6PS2/c1-5-15-9(11)7-8(10(12)16-6-2)19-17(18,13-3)14-4/h8H,5-7H2,1-4H3 Y Key:JXSJBGJIGXNWCI-UHFFFAOYSA-N Y

Malathion is anorganophosphateinsecticide which acts as anacetylcholinesterase inhibitor. In theUSSR, it was known ascarbophos, inNew Zealand andAustralia asmaldison and inSouth Africa asmercaptothion.

Use

Medical

Malathion in low doses (0.5% preparations) is used as a treatment for:

• Head lice andbody lice. Malathion is approved by the USFood and Drug Administration for treatment ofpediculosis.^[5][6] It is claimed to effectively kill both the eggs and the adult lice, but in fact has been shown in UK studies to be only 36% effective on head lice, and less so on their eggs.^[7] This low efficiency was noted when malathion was applied to lice found on schoolchildren in the Bristol area in the UK, and it is assumed^{[by whom?]} to be caused by the lice having developed resistance against malathion.
• Scabies^[8]

Preparations include Derbac-M, Prioderm, Quellada-M^[9] and Ovide.^[10]

Pesticide

Malathion is a pesticide that is widely used in agriculture, residential landscaping, public recreation areas, and in public health pest control programs such as mosquito eradication.^[11] In the US, it is the most commonly used organophosphate insecticide.^[12]

A malathion mixture withcorn syrup was used in the 1980s in Australia and California to combat theMediterranean fruit fly.^[13] In Canada and the US starting in the early 2000s, malathion was sprayed in many cities to combatwest Nile virus.^[14] Malathion was used over the last couple of decades on a regular basis during summer months to kill mosquitoes, but homeowners were allowed to exempt their properties if they chose.^{[citation needed]} Today,Winnipeg is the only major city in Canada with an ongoing malathion adult-mosquito-control program.^[15][16]

Side effects

Malathion is of low toxicity. Its metabolitemalaoxon is 61x more toxic,^[17] being a more potent inhibitor of acetylcholinesterase.^[18]

According to theUnited States Environmental Protection Agency, no reliable information is available on adverse health effects of chronic exposure.^[19] In 1981,B. T. Collins,^[20] director of the California Conservation Corps, publicly swallowed a mouthful of dilute malathion solution to demonstrate its safety following an outbreak of Mediterranean fruit flies in California. Malathion was sprayed over a 1,400 sq mi (3,600 km²) area to control the flies.^[21]

Cancer

Malathion is classified by theIARC asprobable carcinogen (group 2A). Malathion is classified by US EPA as having "suggestive evidence of carcinogenicity".^[22] This classification was based on the occurrence of liver tumors at excessive doses in mice and female rats and the presence of rare oral and nasal tumors in rats that occurred following exposure to very large doses. Exposure to organophosphates is associated withnon-Hodgkin's lymphoma. Malathion used as a fumigant was not associated with increased cancer risk. Between 1993 and 1997, as part of the Agricultural Health Study, no clear association between malathion exposure and cancer was reported.^[23]

Mechanism of action

Malathion is anacetylcholinesterase inhibitor, a diverse family of chemicals. Upon uptake into the target organism, it binds irreversibly to theserine residue in the active catalytic site of the cholinesterase enzyme. The resultant phosphoester group is strongly bound to the cholinesterase, and irreversibly deactivates the enzyme which leads to rapid build-up ofacetylcholine at the synapse.^[24]

Production method

Malathion is produced by the addition ofdimethyl dithiophosphoric acid todiethyl maleate ordiethyl fumarate. The compound is chiral but is used as aracemate.

Other animals

Amphibians

Malathion is toxic to leopard frog tadpoles.^[25]

See also

• Isomalathion
• 1989 California medfly attack
• Pesticide toxicity to bees

References

External links

• Malathion Technical Fact Sheet - National Pesticide Information CenterArchived 2015-04-05 at theWayback Machine
• Malathion General Fact Sheet - National Pesticide Information CenterArchived 2021-02-12 at theWayback Machine
• Malathion Pesticide Information Profile - Extension Toxicology NetworkArchived 2021-04-11 at theWayback Machine
• ATSDR ToxFAQs
• CDC - NIOSH Pocket Guide to Chemical HazardsArchived 2021-03-21 at theWayback Machine
• Re-evaluation of MalathionArchived 2011-01-12 at theWayback Machine by thePest Management Regulatory Agency of Canada
• Malathion in the Pesticide Properties DataBase (PPDB)

• Pages using duplicate arguments in template calls
• Webarchive template wayback links
• Chemical articles with unknown parameter in Infobox drug
• Chemical articles without CAS registry number
• Articles without EBI source
• Chemical pages without ChemSpiderID
• Chemical pages without DrugBank identifier
• Articles without KEGG source
• Articles without UNII source
• Drugs missing an ATC code
• Drugs with no legal status
• Drugboxes which contain changes to verified fields
• Drugboxes which contain changes to watched fields
• Articles with specifically marked weasel-worded phrases from August 2016
• Articles with invalid date parameter in template
• All articles with unsourced statements
• Articles with unsourced statements from August 2016
• Articles with changed EBI identifier
• Acetylcholinesterase inhibitors
• Antiparasitic agents
• Endocrine disruptors
• Insecticides
• Organophosphate insecticides
• Phosphorodithioates