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Parathion-methyl

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Parathion-methyl Basic information
Parathion-methyl Chemical Properties
Safety Information
Parathion-methyl Usage And Synthesis
  • Chemical PropertiesMethyl parathion is a white to yellow-brown, crystalline solid with a garlic odor.It is slightly soluble in water and has a low vapor pressure (U.S. EPA, 2006b).
  • UsesMethyl parathion is a restricted use organophosphate sold under a number of trade names and formulations. First registered in 1954, it is used to control a variety of insect pests on food and feed crops. Methyl parathion is not used in residential settings due to its toxicity to humans, birds, and honey bees. The chemical is a restricted use pesticide with nearly 4 million pounds of active ingredient mainly used on cotton, corn, wheat, soybeans, and rice (U.S. EPA, 2006b).
  • UsesParathion-methyl is an derivative of Parathion (P192220), an organophosphate insecticide used on cotton, rice and fruit trees.
  • UsesMethyl parathion is an insecticide and acaricide used to control boll weevils and many biting or sucking insect pests of agricultural crops. It kills insects by contact, stomach and respiratory action. Methyl parathion is available in dust, emulsifiable concentrate, ULV liquid, microencapsules and wettable powder formulations.
    Methyl parathion is one of a class of insecticides referred to as organophosphates. These chemicals act by interfering with the activities of cholinesterase, an enzyme that is essential for the proper working of the nervous systems of humans, animals and insects.
  • DefinitionChEBI: A C-nitro compound that is 4-nitrophenol substituted by a (dimethoxyphosphorothioyl)oxy group at position 4.
  • General DescriptionMethyl parathion is a white crystalline solid dissolved in a liquid solvent carrier. The commercial product is a tan liquid (xylene solution) with a pungent odor. Parathion-methyl is slightly soluble to insoluble in water. Usually with the liquid solvent Parathion-methyl is a combustible liquid. Parathion-methyl is toxic by inhalation, ingestion and skin absorption. Parathion-methyl is used as an insecticide.
  • Air & Water ReactionsInsoluble in water.
  • Reactivity ProfileMETHYL PARATHION is half decomposed in 8 days at 40°C. When a sample was heated in a small test tube Parathion-methyl decomposed in a few minutes, the residue exploded (Food Chem. 4(1):42. 1956).
  • HazardExplosion risk when heated. Toxicby skin absorption, inhalation, and ingestion;cholinesterase inhibitor. Use has been restricted.Questionable carcinogen.
  • Health HazardParathion-methyl is extremely toxic; the probable oral lethal dose is 5-50 mg/kg, or between 7 drops and 1 teaspoonful for a 150-lb. person. Chronic toxicity does not appear to be a major consideration.
  • Fire HazardPoisonous gases are produced in fire and when heated. Decomposition may lead to sufficient internal pressure to cause the container to rupture violently. Avoid oxidizing materials. Unstable. High temperatures (120F) cause decomposition.
  • Agricultural UsesInsecticide, Nematicide: A U.S. EPA restricted Use Pesticide (RUP). Severely Restricted for use in EU, as parathion-methyl. This material is used as an insecticide on over 50 crops, primarily cotton, but also on walnuts, corn, dried beans and almonds and on several ornamentals. It is no longer allowed to be used on crops consumed by children.
  • Trade nameA-GRO®[C]; AI3-17292®; ATOMIC®[C]; AZOFOS®; AZOPHOS; BAMA BRAND®[C]; BAY 11405®; BAY E-601®; BLADAN M®; CEKUMETHION®; CLEAN CROP®[C]; COTTON TOX DUST®[C]; DALF®; DECLARE®; DEVITHION®; DREXEL METHYL PARATHION 4E®[C]; DURHAM[C]; E 601®; EMMY®[C]; E-Z-FLO®[C]; FALL OUT®[C]; FMC NYNAMITE®[C]; FOLIDOC®; FOLIDOL-80®; FOLIDOL M®; FOLIDOL M-40®; FOSFERNO M 50®; GEARPHOS®; 8056HC®; KILEX PARATHION®; ME-PARATHION®; MEPTOX®; METACID 50®; METACIDE®; METAFOS®; METAPHOS®; METRON®; METHYL-E 605®; METRON®; NITROX®; NITROX® 80; OLEOVOFOTOX®; PARAPEST M-50®; PENNCAP M®; PENNCAP MLS®; QUINOPHOS®; SEIS-TRES 6-3®; SINAFID M-48®; SIXTY-THREE SPECIAL E. C. INSECTICIDE®; TEKWAISA®; THIOPHENIT®; THYLPAR M-50®; TOLL®; VERTAC METHYL PARATHION TECHNISCH 80%®; WOFATOX 50 EC®
  • Contact allergensA case of sensitization to methyl-parathion was described in a female agricultural worker with multiple sensitization.
  • Safety ProfilePoison by inhalation, ingestion, skin contact, subcutaneous, intravenous, and intraperitoneal routes. Fatal poisoning can result from skin or eye contact after very brief exposure to concentrated solution. Experimental teratogenic and reproductive effects. Questionable carcinogen. Human mutation data reported. A cholinesterase inhibitor type of insecticide. When heated to decomposition it emits very toxic fumes of NOx, POx, and SOx.
  • Potential ExposureA severely hazardous pesticide formulation. Alert: This material is used as an insecticide on over 50 crops, primarily cotton, and on several ornamentals
  • CarcinogenicityWhen rats were given diets with 0, 0.5, 2.5, 12.5, and 50 ppm (0, 0.02, 0.1, 0.5, or 2 mg/kg/day (males); 0, 0.02, 0.1, 0.7, or 3 mg/kg/day (females) for 12 months, neuronal degeneration and plasma, erythrocyte, and brain cholinesterase inhibition occurred at 12.5 and 50 ppm .
  • Environmental FateMethyl parathion is mobile in soils and can leach into groundwater and enter surface water as runoff. The chemical breaks down though microbial degradation, aqueous photolysis, hydrolysis, and incorporation into soil organic matter; thus, it degrades rapidly in soil and water with a half-life <5 days. Photodegradation is rapid in aquatic environments with a half-life of 49 h. Bioconcentration is not expected to occur (U.S. EPA, 2006b).
  • Metabolic pathwayParathion-methyl is a non-systemic insecticide and, where studied, metabolism parallels that of parathion and f enitrothion. The major routes of biotransformation involve desulfuration to the oxon analogue (paraoxon-methyl) and hydrolysis to give dimethyl phosphate, dimethyl phosphorothionate and 4-nitrophenol. Demethylation to give desmethylparathion- methyl and reduction of the nitro group also occurs. As with organophosphates, demethylation via glutathione-S-methyl transferases in the liver and some other tissues is an important mechanism in mammals. The major route of phase II metabolism involves conjugation of 4-nitrophenol followed by excretion.
  • ShippingUN3017 Organophosphorus pesticides, liquid, toxic, flammable, flash point not ,23C, Hazard class: 6.1; Labels: 6.1-Poisonous materials, 3.-Flammable liquid. UN2783 Organophosphorus pesticides, solid, toxic, Hazard Class: 6.1; Labels: 6.1-Poisonous material. UN2811 Toxic solids, organic, n.o.s., Hazard Class: 6.1; Labels: 6.1- Poisonous materials, Technical Name Required
  • DegradationParathion-methyl (1) is hydrolysed under acidic and alkaline conditions. The rate is five times faster than for parathion. Upon heating it isomerises via a thonwthiolo rearrangement to yield S-methylparahon-methyl (2) (PM). The hydrolysis of the active anticholinesterase oxon analogue (paraoxon-methyl) (3) is much faster than that of parathion-methyl. The products of parathion-methyl hydrolysis were 4-nitrophenol (4) and dimethyl phosphorothioate (5) (Thuma et al., 1983). Hydrolysis is much more rapid in alkaline than in acidic or neutral media. Photodegradation in natural sunlight led to the formation of O,O,S-trimethyl phosphorothioate (6) and trimethyl phosphate (7) (Chukwudebe et al., 1989). Zweiner et al. (1994) examined the photolysis of parathion-methyl in aqueous solution after irradiation by unfiltered UV light. The major metabolites, which were detected by GC-MS, were paraoxon-methyl (3) and 4-nitrophenol (4). These conversions are shown in Scheme 1.
  • IncompatibilitiesIncompatible with oxidizers, strong bases; heat. Mixtures with magnesium, or endrin may be violent or explosive. Slightly decomposed by acid solutions. Rapidly decomposed by alkalies. Explosive risk when heated above 50C. The liquid xylene solution decomposes violently @ 120C
  • Waste DisposalConsult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform to EPA regulations governing storage, transportation, treatment, and waste disposal. Incineration (816C, 0.5 second minimum for primary combustion; 1204C, 1.0 second for secondary combustion) with adequate scrubbing and ash disposal facilities. In accordance with 40CFR165, follow recommendations for the disposal of pesticides and pesticide containers. Must be disposed properly by following package label directions or by contacting your local or federal environmental control agency, or by contacting your regional EPA office
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