CYPERMETHRIN

IDENTIFICATION

                                                                            

Common name:Cypermethrin

Iupac name: (RS)-(z-cyano-3-phenoxybenzyl (1RS, 3RS;1RS,3SR)-3-(2,2-dichlorovinyl) -2,2-dimethylcyclopropanecarboxylate

Chemical abstracts name:     cyano(3-phenoxyphenyl)methyl 3-(2,2-dichloroethenyl)-2,2- dimethylcyclopropanecarboxylate

Type: Insecticide for Agriculture

CAS RN: [52315-07-8] (formerly [69865-47-0], [86752-99-0] and many other numbers)

M.F.: C₂₂H₁₉Cl₂NO₃

Mol Wt: 416.3

 

Form (appearance): Odourless crystals (pure); (tech., yellow-brown viscous semi-solid at ambient temperatures)

Composition:=Tech. grade is 90% pure
M.P.: 61-83 ℃, depending on isomer ratio

V.P.: 2.0 × 10^-4 mPa (20℃)

F.P.: Not autoflammable; non-explosive

S.G.: 1.24 (20℃)

Solubility: In water 0.004 mg/l (pH 7). In acetone, chloroform, cyclohexanone, xylene >450, ethanol 337, hexane 103 (all in g/I, 20℃)

Stability: Relatively stable in neutral and weakly acidic media, with optimum stability at pH 4. Hydrolysed in alkaline media; DT₅₀ 1.8 d (pH 9, 25℃); stable at pH 5 and 7 (20℃). Relatively stable to light in field situations. Thermally stable up to 220℃

Henry: 2.0 × 10^-2 Pa m³ mol^-1 (calc.)

K_owlogP: 6.6

 

Formulation types: EC;GR; UL; WR

Mode of action: on-systemic insecticide with contact and stomach action. AlSO exhibits anti-feeding action. Good residual activity on treated plants

Uses: Control of a wide range of insects, especially Lepidoptera, but also Coleoptera, Diptera, Hemiptera, and other classes, in fruit (including citrus), vines, vegetables, potatoes, cucurbits, lettuce, capsicums, tomatoes, cereals, maize, soya beans, cotton, coffee, cocoa, rice, pecans, oilseed rape, beet, ornamentals, forestry, etc. Control of flies and other insects in animal houses; and mosquitoes, cockroaches, houseflies and other insect pests in public health. Also used as an animal ectoparasiticide

Compatibility: Incompatible with alkaline materials

 

Oral: Acute oral LD₅₀ for rats 250-4150 (tech. 7180), mice 138 mg/kg.

Skin and eye: Acute percutaneous LD₅₀ for rats >4920, rabbits >2460 mg/kg. Slight skin and eye irritant (rabbits). May be a weak skin sensitiser.

Inhalation: LC₅₀ (4 h) for rats 2.5 mg/l. NOEL (2 y) for dogs 5, rats 7.5 mg/kg.

ADI: (JMPR) 0.05 mg/kg b.w. [1981]; 0.05 mg/kg b.w. (JECFA evaluation) [1996].
Other Oral toxicity values for cypermethrin depend on such factors as: carrier, cis:trans ratio of the sample, species, sex, age and degree of fasting. Values reported sometimes differ markedly.

Toxicity: WHO (a.i.) II; EPA (formulation) II

EC hazard: (Xn; R20/22| R43| N; R50)

 

Birds: Acute oral LD₅₀ for mallard ducks >10000, chickens >2000 mg/kg.

Fish: LC₅₀ (96 h) for rainbow trout 0.69, sheepshead minnow 2.37 μg/l; under field conditions, fish are not at risk from normal agricultural usage.

Daphnia: LC₅₀ (48 h) 0.15 μg/l.

Bees: Highly toxic to honeybees in laboratory tests, but field applications at recommended dosages do not put hives at risk. LD₅₀ (24 h) (oral) 0.035 μg/bee; (topical) 0.02 μg/bee. Other beneficial spp. Not toxic to Collembola (J. A. Wiles & G. K. Frampton, Pestic. Sci., 47, 273 (1996)).

 

Soil/Environment: EHC 82 (WHO, 1989). EHC review concludes that biological degradation is rapid, and consequently levels of cypermethrin and its degradation products in soil and surface waters are very low. Animals For studies of the biotransformation of cypermethrin in animal tissues, see Pestic. Sci., 1987, 21, I and ibid., 1990, 30, 159.
/In soil, typical DT₅₀ 60 d (fine sandy loam); hydrolysis with cleavage of the ester bond occurs and also further hydrolytic and oxidative degradation; see T. R. Roberts & M. E. Standen, Pestic. Sci., 1977, 8, 305. Field dissipation is much faster. In river water, rapid degradation occurs, DT₅₀ c. 5 d.