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Page 3 of 4 KTOXNET PIP - METHOMYL EnvironmentaFFate: . 'Breakdown in soil and groundwater: Methomyl has low persistence in the soil environment, with a reported half-life of approximately 14 days [14]. Because of its high solubility in water, and low affinity for soil binding methomyl may have potential for groundwater contamination [14]. It is very mobile in sandy loam and silty clay loam soils, but only slight leaching was observed in a silt loam and in a sandy soil. Methomyl is rapidly degraded by soil microbes [14]. Methomyl residues are not expected to be found in treated soil after the growing season in which it is applied [14]. . (Breakdown in water: Aqueous solutions of methomyl have been reported to decompose more rapidly on aeration, in sunlight, or in alkaline media [14]. The estimated aqueous half-life for the insecticide is 6 days in surface water and over 25 weeks in groundwater [14]. In one experiment, the hydrolysis half-lives of methomyl in solutions at pHs of 6.0, 7.0 and 8.0 were 54, 38, and 20 weeks respectively. In pure water, the hydrolysis half-life has been estimated to be 262 days [14]. Breakdown in vegetation: Following soil treatment, plants take up methomyl through their roots and move it throughout the plant by a process called "translocation." When methomyl is applied to plants, its residues are ' short-lived [40]. After it is applied to leaves, it has a 3 to 5 day half-life [10]. Less than 3% methomyl remained in cabbage plants 1 week after they were given foliar treatment with the insecticide [8]. Physical Properties: . Appearance: Methomyl is a white, crystalline solid with a slight sulfurous odor. . Chemical Name: S-methyl N-(methylcarbamoyloxy) thioacetimidate [10] . CAS Number: 16752-77-5 . Molecular Weight: 162.21 . Water Solubility: 57.9 g/l @ 25 C [10] . Solubility in Other Solvents: v.s. in methanol, acetone, ethanol, and isopropanol [10] . Melting Point: 79 C [10] . Vapor Pressure: 6.65 mPa @ 25 C[10] . Partition Coefficient: Not Available . Adsorption Coefficient: 72 [13] Exposure Guidelines: . ADI: 0.03 mg/kg/day [10] . MCL: Not Available . RfD: 0.025 mg/kg/day [20] . PEL: 2.5 mg/m3 (8-hour) [3 11 . HA: 0.2 mg/L [39] . TLV: Not Available Basic Manufacturer: DuPont Agricultural Products Walker's Mill, Barley Mill Plaza P.O. Box 80038 Wilmington, DE 19880-0038 k . Phone: 800-441-7515 . Emergency: 800-441-3637 References: References.for the information in this PIP can be found in Reference List Number 3