Cypermethrin 40% EC Most Effective Pesticide Insecticide CAS
Composition Tech. grade is 90% pure. Mol. wt. 416.3 M.f. C22H19Cl2NO3 Form Odourless crystals; (tech., yellow-brown viscous semi-solid at
ambient temperatures). M.p. 61-83 °C, depending on isomer ratio V.p. 2.0 ´ 10-4 mPa (20 ºC) KOW logP = 6.6 Henry 2.0 ´ 10-2 Pa m3 mol-1 (calc.) S.g./density 1.24 (20 ºC) Solubility In water 0.004 mg/l (pH 7). In acetone, chloroform, cyclohexanone,
xylene >450, ethanol 337, hexane 103 (all in g/l, 20 ºC). 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 °C); stable at pH 5 and 7 (20 °C). Relatively
stable to light in field situations. Thermally stable up to 220 ºC. F.p. Not auto-flammable; non-explosive
Biochemistry Acts on the nervous system of the insect, disturbs the function of
neurons by interaction with the sodium channel. Mode of action Non-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.
Product analysis of pyrethroids reviewed by E. Papadopoulou-Mourkidou in Comp. Analyt. Profiles. By glc with FID (AOAC Methods, 17th Ed., 985.03, 986.02; CIPAC Handbook, 1985, 1C, 2047; A. Sapiets et al., Anal. Methods Pestic. Plant Growth Regul., 1984, 13, 33); total cypermethrin and diastereoisomer ratio by hplc with
u.v. detection (CIPAC Handbook, 1985, 1C, 2052. 1994). Residues determined by glc with ECD (idem, ibid.; AOAC Methods, 17th Ed., 998.01). Details available from BASF or Syngenta.
Reviews See A. J. Gray & D. M. Soderlund, Chapt. 5 in "Insecticides". See also JECFA 47, FAO/WHO 36, 37 (see part 2 of Bibliography). 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 (JECFA evaluation) 0.05 mg/kg b.w. ; (JMPR) 0.05 mg/kg b.w.
. 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 class WHO (a.i.) II; EPA (formulation) II EC classification (Xn; R20/22| R43| N; R50)
Birds Acute oral LD50 for mallard ducks >10 000, chickens >2000 mg/kg. Fish LC50 (96 h) for rainbow trout 0.69, sheepshead minnow 2.37 mg/l; under field conditions, fish are not at risk from normal
agricultural usage. Daphnia LC50 (48 h) 0.15 mg/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 mg/bee; (topical) 0.02 mg/bee. Other beneficial spp. Not toxic to Collembola (J. A. Wiles & G. K. Frampton, Pestic. Sci., 47, 273 (1996)).
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, 1 and ibid., 1990, 30, 159. Soil/Environment 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. Koc 26 492-144 652; Kf 821-1042; not pH dependent. In river water, rapid degradation
occurs, DT50 c. 5 d. DT50 for photochemical oxidative degradation in air 3.47 h.