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 | |
| Names | |
|---|---|
| Preferred IUPAC name O,O-DiethylO-(4-nitrophenyl) phosphorothioate | |
| Other names E605 | |
| Identifiers | |
| |
3D model (JSmol) | |
| 2059093 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
|
| ECHA InfoCard | 100.000.247 |
| EC Number |
|
| KEGG |
|
| RTECS number |
|
| UNII | |
| UN number | 3018 2783 |
| |
| |
| Properties | |
| C10H14NO5PS | |
| Molar mass | 291.26 g·mol−1 |
| Appearance | White crystals (pure form) |
| Melting point | 6 °C (43 °F; 279 K) |
| 24 mg/L | |
| Solubility in other solvents | high solubility inxylene andbutanol |
| Hazards | |
| GHS labelling: | |
   | |
| Danger | |
| H300,H311,H330,H372,H410 | |
| P260,P264,P270,P271,P273,P280,P284,P301+P310,P302+P352,P304+P340,P310,P312,P314,P320,P321,P322,P330,P361,P363,P391,P403+P233,P405,P501 | |
| NFPA 704 (fire diamond) | |
| Flash point | 120 °C (248 °F; 393 K) |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | 5 mg/kg (mouse, oral) 10 mg/kg (rabbit, oral) 3 mg/kg (dog, oral) 0.93 mg/kg (cat, oral) 5 mg/kg (horse, oral) 8 mg/kg (guinea pig, oral) 2 mg/kg (rat, oral)[3] |
LC50 (median concentration) | 84 mg/m3 (rat, 4 hr)[3] |
LCLo (lowest published) | 50 mg/m3 (rabbit, 2 hr) 14 mg/m3 (guinea pig, 2 hr) 15 mg/m3 (mouse)[3] |
| NIOSH (US health exposure limits): | |
PEL (Permissible) | none (methyl parathion),[1] TWA 0.1 mg/m3 [skin] (ethyl parathion)[2] |
REL (Recommended) | TWA 0.2 mg/m3 [skin] (methyl parathion)[1] TWA 0.05 mg/m3 [skin] (ethyl parathion)[2] |
IDLH (Immediate danger) | N.D. (methyl parathion)[1] 10 mg/m3 (ethyl parathion)[2] |
| Safety data sheet (SDS) | [1] |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Parathion, also calledparathion-ethyl ordiethyl parathion, is anorganophosphateinsecticide andacaricide. It was originally developed byIG Farben in the 1940s. It is highly toxic to non-target organisms, including humans, so its use has been banned or restricted in most countries. In response to safety concerns, the less toxic but still dangerous analogueparathion methyl was later developed.[5][6]
Parathion was developed byGerhard Schrader for the German trustIG Farben in the 1940s. AfterWorld War II and the collapse of IG Farben due to the war crime trials, the Western allies seized thepatent, and parathion was marketed worldwide by different companies and under different brand names. The most common German brand wasE605 (banned in Germany after 2002); this was not a food-additive "E number" as used in the EU today. "E" stands forEntwicklungsnummer (German for "development number"). It is an irreversibleacetylcholinesterase inhibitor.
Safety concerns later led to the development ofparathion methyl, which is somewhat less toxic.
In theEU, Parathion was banned after 2001.[7] InSwitzerland, the substance is no longer approved as a pesticide.
Pure parathion is a white crystalline solid. It is commonly distributed as a brownliquid that smells of rottingeggs orgarlic. The insecticide is somewhat stable, although it darkens when exposed to sunlight.
Parathion is synthesized fromdiethyl dithiophosphoric acid(C2H5O)2PS2H bychlorination to generate diethylthiophosphoryl chloride ((C2H5O)2P(S)Cl), and then the chloride is treated withsodium 4-nitrophenolate (thesodiumsalt of4-nitrophenol).[8]
As a pesticide, parathion is generally applied by spraying. It is often applied tocotton,rice andfruit trees. The usual concentrations of ready-to-use solutions are 0.05 to 0.1%. The chemical is banned for use on many food crops.
Parathion acts on the enzymeacetylcholinesterase indirectly. After an insect (or a human) ingests parathion, anoxidase replaces the double bonded sulfur with oxygen to giveparaoxon.[9]
The phosphate ester is more reactive in organisms than the phosphorothiolate ester, as the phosphorus atoms become much more electropositive.[9]
Parathionresistance is a special case ofacetylcholinesterase inhibitor resistance.
Degradation of parathion leads to more water-soluble products.Hydrolysis, which deactivates the molecule, occurs at thearyl ester bond[9] resulting indiethyl thiophosphate and4-nitrophenol.
Degradation proceeds differently underanaerobic conditions: the nitro group on parathion is reduced to theamine.
Parathion is acholinesterase inhibitor. It generally disrupts thenervous system by inhibitingacetylcholinesterase. It is absorbed via skin, mucous membranes, and orally. Absorbed parathion is rapidly metabolized to paraoxon, as described inInsecticidal activity. Paraoxon exposure can result inheadaches,convulsions, poor vision,vomiting, abdominal pain, severediarrhea,unconsciousness,tremor,dyspnea, and finallypulmonary edema as well as respiratory arrest. Symptoms of poisoning are known to last for extended periods, sometimes months. The most common and very specific antidote isatropine, in doses of up to 100 mg daily. Because atropine may also be toxic, it is recommended that small frequently repeated doses be used in treatment. If human poisoning is detected early and the treatment is prompt (atropine and artificial respiration), fatalities are infrequent. Insufficient oxygen will lead tocerebral hypoxia and permanent brain damage.Peripheral neuropathy includingparalysis is noticed as latesequelae after recovery from acute intoxication. Parathion and related organophosphorus pesticides are used in hundreds of thousands of poisonings annually, especially suicides.[10] It is known asSchwiegermuttergift (mother-in-law poison) in Germany. For this reason, most formulations contain a blue dye providing warning.
Parathion was used as achemical warfare agent, most notably by an element of theBritish South Africa Police attached to theSelous Scouts during theRhodesian Bush War. They used it to poison clothing that was then supplied to anti-government guerrillas. When the enemy soldiers put on the clothes, they were poisoned by absorption through the skin.[11][12][13]
Based on animal studies, parathion is considered by theU.S. Environmental Protection Agency to be a possible humancarcinogen.[14] Studies show that parathion is toxic to fetuses, but does not cause birth defects.[15]
It is classified by theUnited Nations Environment Programme as apersistent organic pollutant[16] and by theWorld Health Organization asToxicity Class Ia (extremely hazardous).[17]
Parathion is toxic tobees,fish,birds, and other forms of wildlife.[15]
To provide the end user with a minimum standard of protection, suitable protective gloves, clothing, and a respirator with organic-vapour cartridges is normally worn.Industrial safety during the production process requires special ventilation and continuous measurement of air contamination in order not to exceed PEL levels, as well as careful attention to personal hygiene. Frequent analysis of workers' serum acetylcholinesterase activity is also helpful with regards to occupational safety, because the action of parathion is cumulative. Also, bothatropine andmemantine have been used as a specific antidote.[18][19]
A chemist[who?] swallowed .00424 ounces (0.120 g) of parathion[when?] to find the most lethal means of exposure to humans, intending to take an antidote afterwards, but was paralyzed and so died before he could reach it.[20]
Parathion was commonly used for suicides in the 1950s and 1960s.[20]
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