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Physical Properties
Molecular weight:241.5; Physical form:Colourless powder, with a chlorine-like odour. Composition:Tech. is 79.5%. Melting point:Decomposes at c. 215 °C without melting; Vapour pressure:8.4 × 10-2 mPa (25 °C); Henry constant:4.7 × 10-5 Pa m3 mol-1; Partition coefficient(n-octanol and water):logP = 1.9 (20 °C, 0.1N HCl, i.e. neutral species); pKa:2.3 (22 °C); Solubility:In water 430 mg/l (25 °C). In acetone 19.8, ethanol 10.5, isopropanol 5.5, acetonitrile 1.6, diethyl ether 1.2, dichloromethane 0.6, benzene 0.2, carbon disulfide <0.05 (all in g/l, 25 °C).; Stability:Very stable to acids and alkalis, but decomposed by hot concentrated alkalis. Readily forms water-soluble alkali-metal and amine salts. In aqueous solution, decomposed by u.v. irradiation, DT50 2.6 d (25 °C).
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Toxicology
Oral:Acute oral LD50 for male rats >5000, mice 2000-4000, rabbits c. 2000, guinea pigs c. 3000, sheep >1000, cattle >750 mg/ kg. Percutaneous:Acute percutaneous LD50 for rabbits >2000 mg/kg. Moderate eye irritant; mild skin irritant (rabbits). No skin sensitisation. Inhalation: LC50 for male and female rats >0.035 mg/l (picloram); >1.63 mg/l (potassium salt); >0.035 mg/l (isooctyl ester); >0.07 mg/l (triisopropylammonium
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Environmental Profile
Ecotoxicology:
Algae: EC50 for Selenastrum 36.9 mg/l.Bees: LD50 for honeybees >100µg/bee.Birds:Acute oral LD50 for chicks c. 6000 mg/kg. LC50 for mallard ducks, bobwhite quail >5000 mg/ kg diet.Daphnia:LC50 34.4 (picloram); 63.8 (potassium salt) (both in mg/l).Fish:LC50 (96 h) for rainbow trout 5.5 (picloram); 26 (potassium salt); 41.4 (triethylammonium salt); 51 (triisopropanolammonium salt) (all in mg/l); for bluegill sunfish 14.5 (picloram); 109 (triisopropanolammoniumWorms:Practically non-toxic to earthworms.Other aquatic spp.:LC50 for pink shrimp 10.3 mg/l.
Environmental fate:
Once in the plant or in the environment, all salt and ester forms are readily converted to picloram acid. For reviews of picloram in the environment, see M. Mayes & G. R. Oliver, "An Aquatic Hazard Assessment: Picloram", Aquatic Toxicology and Hazard AsseAnimals:In mammals, following oral administration, picloram is rapidly excreted in an unchanged form.Soil:Degraded by light, more rapidly on the soil surface or in clear, moving water. Degraded slowly by soil micro-organisms, DT50 30-90 d. Rate of degradation in soil strongly proportional to application rate. Aqueous photodegradatioPlant:On plant surfaces, photodecomposition occurs, possibly with cleavage of the pyridine ring. WATER SOLUBILITY: 0.056 g/100 ml at 20° C
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Transport Information
Signal Word:WARNING; Hazard Class:II(Moderately hazardous)