Common name: tefluthrin; téfluthrine
IUPAC name: 2,3,5,6-tetrafluoro-4-methylbenzyl (Z)-(1RS,3RS)-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate
Roth: 2,3,5,6-tetrafluoro-4-methylbenzyl (Z)-(1RS)-cis-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate
Chemical Abstracts name: [1a,3a(Z)]-(2,3,5,6-tetrafluoro-4-methylphenyl)methyl 3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethylcyclopropanecarboxylate
CAS RN: [79538-32-2]
PHYSICAL CHEMISTRY
Composition: Tech. material is c. 92% pure. Mol. wt.: 418.7; M.f.: C17H14ClF7O2; Form: Colourless solid; (tech., off-white). M.p.: 44.6 ºC; (tech., 39-43 ºC). B.p.: 156 ºC/1 mmHg. V.p.: 8.4 mPa (20 ºC); 50 mPa (40 ºC). KOW: logP = 6.4 (20 ºC); Henry: 2x102 Pa m3 mol-1 (calc.) S.g./density: 1.48 g/ml (25 ºC). Solubility: In water 0.02 mg/l (purified and buffered, pH 5 and 9, 20 ºC). In acetone, hexane, toluene, dichloromethane, ethyl acetate >500, methanol 263 (all in g/l, 21 ºC). Stability: Stable for at least 9 months at 15-25 ºC. Stable for >84 days at 50 ºC. Stable to hydrolysis at pH 5-7 for >30 days. At pH 9, 7% hydrolysis in 30 days. At pH 7, 27-30% loss in aqueous solution exposed to sunlight for 31 days. pKa: >9 (hydrolysis prevents measurement). F.p.: 124 ºC.
APPLICATIONS
Uses: Control of a wide range of soil insect pests, particularly those of the orders Coleoptera, Lepidoptera, and Diptera, in maize, sugar beet, wheat and other crops.
Formulation types: CS; EC; GR.
MAMMALIAN TOXICOLOGY
Oral: Oral and percutaneous LD50 values of tefluthrin depend on such factors as carrier, the test species, its sex, age and degree of fasting; values reported sometimes differ markedly. Acute oral LD50 for male rats 22, female rats 35 (corn oil carrier), male mice 46, female mice 57 mg/kg.
Skin and eye: Acute percutaneous LD50 for male rats 316, female rats 177 mg/kg. Slight eye and skin irritation (rabbits). No skin sensitisation (guinea pigs).
Inhalation: LC50 (4 h) for male rats 0.05, female rats 0.04 mg/l.
NOEL: (2 y) for rats 25 mg/kg diet; (1 y) for dogs 0.5 mg/kg daily.
ADI: 0.005 mg/kg.
Toxicity class: WHO (a.i.) Ib
EC hazard: (T+ R26/28 | R24 | N; R50)
ECOTOXICOLOGY
Birds: Acute oral LD50 for mallard ducks 4190, bobwhite quail 730 mg/kg. Sub-acute dietary LC50 (5 d) for mallard ducks 2317, bobwhite quail 15 000 mg/kg.
Fish: LC50 (96 h) for rainbow trout 60, bluegill sunfish 130 ng/l. Under field conditions, adsorption of tefluthrin on bottom and suspended sediments should prevent any hazard.
Daphnia: EC50 (48 h) 70 ng/l.
Algae: >1.05 mg/l.
Bees: LD50 (contact) 280 ng/bee; (oral) 1880 ng/bee.
Worms: 0.32 mg/kg soil.
ENVIRONMENTAL FATE
Plants: No residues have been found on major crops treated at recommended rates (limit of detection 0.01 mg/kg).
Soil/Environment: DT50 in soil 150 d (5 ºC), 24 d (20 ºC), 17 d (30 ºC), partly due to loss by volatilisation. At normal application rates, there was no effect on soil microflora or earthworms.
