Physical Properties
Molecular weight:191.2; Physical form: Crystalline powder,odorless solid. Density:1.45 (20 °C); Melting point:302-307 °C (decomp.); Vapour pressure:0.09 mPa (20 °C); 0.15 mPa (25 °C); 1.3 mPa (50 °C); separate study gives <0.0001 mPa (20 °C); Henry constant:3.6×10-3 Pa m3 mol-1 (calc.); Partition coefficient(n-octanol and water):logP = 1.38 (pH 5), 1.51 (pH 7), 1.49 (pH 9); pKa:4.2, weak base; Solubility:In water 29 mg/l (pH 4), 8 mg/l (pH 7), 7 mg/l (pH 8) (24 °C). In dimethylformamide 5, acetone 0.3, ethanol 0.3, chloroform 0.1, ethyl acetate 0.135, dic; Stability:Decomposes at m.p.; stable for at least 2 y below 50 °C. Stable after 7 d at 20 000 lux. Slowly decomposed in alkaline solution (22 °C); DT50 >350 d (pH 5 and pH 7), 124 d
Toxicology
Oral:Acute oral LD50 for rats >15 000 mg/kg(in sesame oil), dogs >2500 mg/kg. Percutaneous:Acute percutaneous LD50 for rabbits >10 000, rats >2000 mg/kg. Non-irritating to skin and eyes (rabbits). Not a skin sensitiser (guinea pigs). Inhalation:LC50 (4 h) for rats, rabbits, guinea pigs or cats, no effect with suspension (10 g/l water). ADI:(JMPR) 0.003 mg/kg b.w.[2000].
Environmental Profile
Ecotoxicology: Algae:EC50 (72 h) for Scenedesmus subspicatus 419, Selenastrum capricornutum 1.3 mg/l.Bees: LD50 (contact) >50 mg/bee.Birds:Acute oral LD50 for quail 5826-15 595 mg/kg.Daphnia: LC50 (48 h) 0.13-0.22 mg/l.Fish:LC50 (96 h) for carp 0.61 mg/l, rainbow trout 0.83 mg/l, bluegill sunfish >17.25 mg/l, guppy >8 mg/l. Worms:LC50 (4 w) for Eisenia foetida 6 mg/kg soil. Environmental fate: EHC 149 concludes that, although highly toxic to aquatic organisms, low bioavailability in surface waters makes it unlikely this toxicity will occur in the field.Animals:In male rats, following a single oral administration of 3 mg/kg, 66% was eliminated in the urine within 6 hours.Soil:2-Aminobenzimidazole has been found as a minor metabolite. DT50in soil 8-32 d under outdoor conditions. Carbendazim decomposes in the environment, DT50 6-12 mo on bare soil, 3-6; Plant:Readily absorbed by plants. One degradation product is 2-aminobenzimidazole.
Transport Information
Signal Word:CAUTION; Hazard Class:III (Slightly hazardous)
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