CHLORPYRIFOS

Common name: Chlorpyrifos

Chemical name: O,O -diethyl O -3,5,6-trichloro-2-pyridyl phosphorothioate

Structural formula:

Chemical class: Organophosphorus insecticide

CAS No.: 2921-88-2

Properties: Technical product is light yellow to white crystal. M.p. 42-43.5 ℃ . V.p. 2.7 mPa (25 ℃ ). Soluble in water c. 1.4mg/L (25 ℃ ). In benzene 7900, acetone 6500, chlorform 6300, carbon disulfide 5900, diethyl ether 5100, xylene 5000, iso-octanol 790, methanol 450 (all in g/kg, 25 ℃ ). Rate of hydrolysis increases with pH, and in the presence of copper and possibly of other metals that can form chelates.

Toxicity: Acute oral LD 50 for rats 135-163, guinea pigs 504, rabbits 1000-2000mg/kg. Acute percutaneous LD 50 (in solutions) for rabbits c. 2000 mg/kg; for rats ﹥ 2000 mg/kg. Inhalational LC 50 (4-6 h) for rats ﹥ 0.2 mg/L ( 14 ppb).

Ecotoxicology: Birds, acute oral LD 50 for chickens 32-102 mg/kg. LC 50 (8 d) for bobwhite quail 423 ppm. Fish, LC 50 (96 h) for rainbow trout 0.003, roach 0.25 mg/L. Bees, toxic to bees. LD 50 (contact) 59 ng/bee, (oral) 250 ng/bee. Daphnia, LC 50 (48 h) 1.7 μ g/L.

Environmental fate: Animals, in rats, dogs, and other mammals, following oral administration, rapid metabolism occurs, the principal metabolite being 3,5,6-trichloro-2-pyridinol. Excretion is principally in the urine. Plants, non-systemic in plants, not absorbed from soil via the roots. Residues taken up by plant tissues are metabolized to 3,5,6-trichloro-2-pyridinol which is conjugated and sequestered. Soil/Environment, in soil, chlorpyrifos is slowly degreded, DT 50 c.60-120 d, to 3,5,6-trichloropyridin-2-ol, which is subsequently degraded to organochlorine compounds and CO 2 .

Treatment: Antidote: Atropine.

    Get medical aid. Eyes, flush immediately with plenty of water. Skin, wash thoroughly with soap and water. Remove contaminated clothing and shoes. Inhalation, remove to fresh air. Ingestion, drink 1-2 glass of water; induce vomiting by touching back of throat with finger. Never give anything by mouth to an unconscious person.

Mode of action: Non-systemic insecticide with contact, stomach, and respiratory action.

Usage: Control of Coleoptera, Diptera, Homoptera and Lepidoptera in soil or on foliage in a wide range of crops, including pome fruit, stone fruit, citrus fruit, nut crops, strawberries, figs, bananas, vines, vegetables, potatoes, beet, tobacco, soya beans, sunflowers, sweet potatoes, peanuts, rice, cotton, alfalfa, cereals, maize, sorghum, asparagus, glasshouse and outdoor ornamentals, mushrooms, surf, and in forestry. Also used for control of household pests and in animal houses. Also for stored product.