Parathion-methyl

Parathion-methyl

甲基对硫磷

O,O-dimethyl O-4-nitrophenyl phosphorothioate

O,O-dimethyl O-(4-nitrophenyl) phosphorothioate

298-00-0

C₈H₁₀NO₅PS

Insecticides > Organophosphorus insecticides

Insecticide

Parathion-methyl+trichlorfon
Parathion-methyl+phoxim
Methamidophos+parathion-methyl
Endosulfan+parathion-methyl
Cyhalothrin+parathion-methyl+isocarbophos

Molecular weight:263.2; Physical form:Colourless, odourless crystals; ( tech., light to dark tan-coloured liquid). Density:1.358 (20 °C); ( tech., 1.20-1.22); Melting point:35-36 °C; ( tech., c. 29 °C); Flash point:>150 °C ( tech.); Vapour pressure:0.2 mPa (20 °C); 0.41 mPa (25 °C); Henry constant:8.57 × 10-3 Pa m3 mol-1; Partition coefficient(n-octanol and water):logP = 3.0; Solubility:In water 55 mg/l (20 °C). Readily soluble in common organic solvents, e.g. dichloromethane, toluene >200, hexane 10-20 (all in g/l, 20 °C). Sparingly soluble in petroleum ether and some types of mineral oil.; Stability:Hydrolysed in alkaline and acidic media (c. 5 more rapidly than parathion); DT50 (25 °C) 68 d ( pH 5), 40 d ( pH 7), 33 d ( pH 9).

Oral:Acute oral LD₅₀ for rats c. 3, male mice c. 30, male and female rabbits 19 mg/ kg. Percutaneous:Acute percutaneous LD₅₀ (24 h) for male and female rats c. 45 mg/kg. Not irritating to skin and eyes (rabbits). Not a skin sensitiser. Inhalation: LC₅₀ (4 h) for rats c. 0.17 mg/l air (aerosol). Phytotoxicity:Non-phytotoxic when used as recommended. Alfalfa, sorghum, certain varieties of apple, cucurbit leaves (when wet), peach

Ecotoxicology: 
Algae: E_rC₅₀ for Scenedesmus subspicatus 3 mg/l.Bees:Toxic to bees.Birds: LC₅₀ (5 d) for mallard ducks 1044 mg (as EC 480)/ kg.Daphnia: LC₅₀ (48 h) 0.0073 mg/l.Fish: LC₅₀ (96 h) for rainbow trout 2.7, golden orfe 6.9 mg/l.Worms: LC₅₀ for Eisenia foetida 40 mg/ kg dry soil. 

Environmental fate: 
EHC 145 concludes that, because of toxicity to bees and other beneficial organisms, spraying should be timed with great care.Animals:In mammals, following oral administration, parathion-methyl is almost completely excreted in the urine within 24 hours. The major metabolites in man are 4-nitrophenol and dimethyl phosphate.Soil:Based on the K_oc values and leaching studies, parathion-methyl can be classified as a compound with low/medium mobility. In biologically-active soils, parathion-methyl is rapidly degraded. As for phosphorothioates in general, mPlant:The major metabolites formed in plants are 4-nitrophenol, 4-nitrophenyl glucopyranoside and P-S-demethyl parathion-methyl.

Hazard Class:Ia(Extremely hazardous)