 | |
 | |
 | |
| Names | |
|---|---|
| IUPAC name Diethyl 2-[(dimethoxyphosphorothioyl)sulfanyl]butanedioate | |
Other names
| |
| Identifiers | |
| |
3D model (JSmol) | |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
|
| DrugBank |
|
| ECHA InfoCard | 100.004.089 |
| KEGG |
|
| UNII | |
| |
| |
| Properties | |
| C10H19O6PS2 | |
| Molar mass | 330.35 g·mol−1 |
| Appearance | Clear colorless liquid |
| Odor | mercaptan-like, skunk-like, or garlic |
| Density | 1.23 g/cm3 |
| Melting point | 2.9 °C (37.2 °F; 276.0 K) |
| Boiling point | 156 to 157 °C (313 to 315 °F; 429 to 430 K) at 0.7 mmHg (93 Pa) |
| 145 mg/L (20 °C (68 °F; 293 K))[1] | |
| Solubility indiethyl ether | very soluble |
| Solubility inethanol | soluble |
| Solubility inacetone | soluble |
| logP | 2.36 (octanol/water)[2] |
| Pharmacology | |
| P03AX03 (WHO) QP53AF12 (WHO) | |
| Hazards | |
| GHS labelling:[4] | |
  | |
| Warning | |
| H302,H317,H410 | |
| P261,P264,P270,P272,P273,P280,P301+P312+P330,P302+P352,P333+P313,P363,P391,P501 | |
| Flash point | 163 °C; 325 °F; 436 K (greater than) |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | |
LC50 (median concentration) | >5.2 mg/L (inhalation, rat) |
| NIOSH (US health exposure limits):[5] | |
PEL (Permissible) | 15 mg/m3 (TWA, skin) |
REL (Recommended) | 10 mg/m3 (TWA, skin) |
IDLH (Immediate danger) | 250 mg/m3 |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Malathion is anorganophosphateinsecticide which acts as anacetylcholinesterase inhibitor. In theUSSR, it was known ascarbophos, inNew Zealand andAustralia asmaldison and inSouth Africa asmercaptothion.
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.[6] In the US, it is the most commonly used organophosphate insecticide.[7]
A malathion mixture withcorn syrup was used in the 1980s in Australia to combat theMediterranean fruit fly.[8] In Canada and the US starting in the early 2000s, malathion was sprayed in many cities to combatwest Nile virus.[9]
In the United Kingdom, malathion was withdrawn from sale in 2002.[10]
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.[11]
Malathion is produced by the addition ofdimethyl dithiophosphoric acid todiethyl maleate or diethyl fumarate in the presence of catalytic amounts oftriethylamine andhydroquinone at elevated temperature:
This process produces theSenantiomer.[12]
Malathion in low doses (0.5% preparations) is used as a treatment forhead lice andbody lice infection (pediculosis) in the US, where it is approved by the USFood and Drug Administration.[13][14] In some areas in the UK, head lice had developed a resistance to malathion as of 1999[update], and it was ineffective against 64% of cases. This is believed to be caused by development in the lice of an enzyme-mediated malathion specific esterase, able to destroy malathion bound to the acetylcholine receptor.[15]
It is also used for the treatment of scabies.[16][page needed]
Preparations include Derbac-M, Prioderm, Quellada-M and Ovide.[17][18]
Malathion is of low toxicity. It metabolizes to the more toxicmalaoxon in many species.
In arthropods it is metabolized into malaoxon which is 61x more toxic, being a more potent inhibitor of acetylcholinesterase.[3] In studies of the effects of long-term exposure to oral ingestion of malaoxon in rats, malaoxon has been shown to be 61 times more toxic than malathion, and malaoxon is 1,000 times more potent than malathion in terms of its acetylcholinesterase inhibition.[19][20]
Absorption or ingestion into the human body also readily results in its metabolism to malaoxon, which is substantially more toxic.[19] It is cleared from the body quickly, in three to five days.[medical citation needed] According to theUnited States Environmental Protection Agency, no reliable information is available on adverse health effects of chronic exposure.[21]
In 1981, Malathion was sprayed over a 1,400 sq mi (3,600 km2) area to control an outbreak of Mediterranean fruit flies in California. In order to demonstrate the chemical's safety,B. T. Collins, director of the California Conservation Corps, publicly swallowed a mouthful of dilute malathion solution.[22]
Malathion is classified by theIARC asprobable carcinogen (group 2A). Malathion is classified by US EPA as having "suggestive evidence of carcinogenicity".[3] 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]
Malathion is toxic toleopard frog tadpoles.[24]
Different organizations and governments have set differentdrinking water quality standards for malathion.
TheWorld Health Organization has determined that while malathion can last in water for months and years, it usually does not last in water for longer than one to two weeks; and since the amount of malathion found in drinking water is usually lower than a level that would lead to concerns about health that there is no need to set a drinkingwater guideline for the level of malathion allowed in water.[25]
In contrast, the Canadian government has set a maximum acceptable concentration of0.29 mg/L of malathion in drinking water, and requires that drinking water should be monitored for the chemical when there is a reason to suspect it is in the water and might need to be removed.[26]
Australia has a much lower maximum level of0.07 mg/L of malathion in drinking water.[27]
The European Union has set their level still lower at0.10 μg/L for any one pesticide in drinking water, including malathion.[28]
The United States does not have an officialmaximum contaminant level for malathion, but proposes a lifetimehealth advisory of0.5 mg/L.[29]
An extensive re-evaluation of malathion was completed by the US Environmental Protection Agency in 2000. The PMRA has also re-evaluated malathion and approved its use as a mosquito adulticide.
| International | |
|---|---|
| National | |
| Other | |
