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?XTOXNET PIP -DIMETHOATE Page 3 of Ecological Effects: . Effects on birds: Dimethoate is moderately to very highly toxic to birds. In Japanese quail, a 5-day dietary LC50 341 ppm is reported [14]. It may be very highly toxic to other birds; reported acute oral LD50 values are 41.7 to 63.5 mg/kg in mallards and 20.0 mg/kg in pheasants [6]. Birds are not able to metabolize dimethoate as rapidly as mammals do,which may account for its relatively higher toxicity in these species [26]. . Effects on aquatic organisms: Dimethoate is moderately toxic to fish, with reported LC50 values of 6.2 mg/L in rainbow trout, and 6.0 mg/L in bluegill sunfish [16]. It is more toxic to aquatic invertebrate species such as stoneflies and scuds [16]. . Effects on other organisms: Dimethoate is highly toxic to honeybees. The 24-hour topical LD50 for dimethoate 1 bees is 0.12 ug per bee [13]. :nvironmental Fate: . Breakdown in soil and groundwater: Dimethoate is of low persistence in the soil environment. Soil half-lives of 4 to 16 days, or as high as 122 days have been reported,but a representative value may be on the order of 20 days [12,19]. Because it is rapidly broken down by soil microorganisms, it will be broken down faster in moist soils. Dimethoate is highly soluble in water, and it adsorbs only very weakly to soil particles so it may be subject to considerable leaching [12,19]. However, it is degraded by hydrolysis, especially in alkaline soils, and evaporates from dry soil surfaces. Losses due to evaporation of 23 to 40% of applied dimethoate have been reported [12]. Biodegradation may be significant, with a 77% loss reported in a nonsterile clay loam soil after 2 weeks [12]. . Breakdown in water: In water, dimethoate is not expected to adsorb to sediments or suspended particles, nor to bioaccumulate in aquatic organisms [12]. It is subject to significant hydrolysis, especially in alkaline waters. The half-life for dimethoate in raw river water was 8 days,with disappearance possibly due to microbial action or chemical degradation [12]. Photolysis and evaporation from open waters are not expected to be significant [12]. . Breakdown in vegetation: Dimethoate is not toxic to plants [13]. 'hysical Properties: . Appearance: Dimethoate is a grey-white crystalline solid at room temperature [13]. . Chemical Name: 0,0-dimethyl S-methylcarbamoylmethyl phosphorodithioate [13] . CAS Number: 60-51-5 . Molecular Weight: 229.28 • Water Solubility: 25 g/L @ 21 C [13] . Solubility in Other Solvents: s. in methanol and cyclohexane; s.s in aliphatic hydrocarbons, aromatic hydrocarbons, diethyl ether, carbon tetrachloride, hexane, and xylene; v.s. in chloroform, benzene . Melting Point: 43-45 C (technical) [13] . Vapor Pressure: 1.1 mPa @ 25 C [13] . Partition Coefficient: 0.6990 [13] . Adsorption Coefficient: 20 [19] ppsure Guidelines: . ADI: 0.01 mg/kg/day [38] . MCL: Not Available . RfD: 0.0002 mg/kg/day [53] . PEL: Not Available . HA: Not Available • TLV: Not Available ttp:Hextoxnet.orst.edu/pips/dimethoa.htm 6/25/20(