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!XFO\NGT PIP-FENAMII1110S 'n:Hace.orst.edu/cgi-bin/mf's/01/pips/fcnamiph.htm Ecological Effects: • Effects on birds: Fenamiphos is very highly toxic to birds, with a reported acute oral LD50 for the most sensitive species tested, the ring-necked pheasant, of 0.5 mg/kg [6]. LD50 values for other species range from 1.0 to 2.4 mg/kg, all of which indicate that this is a very highly toxic compound [6]. In a controlled experiment, fenamiphos was determined to be the most toxic of thirteen different cholinesterase inhibitors [66]. In tests with wild songbirds (red-winged blackbirds and house sparrows) an unspecified dose of Nemacur was highly toxic to these species, with death of the birds occurring within an hour of eating the granules [66]. • Effects on aquatic organisms: The toxicity of fenamiphos to aquatic species varies from moderate to high. Bluegill sunfish are extremely sensitive to the presence of the compound. The LC50 for fenamiphos is 9.6 mg/L in this species. Other species tested include the rainbow trout (LC50 is 0.11 mg/L) and the goldfish (LC50 is 3.2 mg/L) [8]. The compound is not expected to bioaccumulate appreciably in aquatic organisms [6]. • Effects on other organisms: Fenamiphos is practically nontoxic to honeybees [8]. Environmental Fate: • Breakdown in soil and groundwater: Fenamiphos is of moderate persistence in the soil environment, with a reported soil half-life of about 50 days [19]. The compound appears to have no effect on the activity of soil bacteria [8]. Aerobic processes are most important for breakdown of the compound. Fenamiphos is not strongly adsorbed to soils [19], but neither it nor its breakdown products have been found in over 1200 wells tested in six states. • Breakdown in water: Fenamiphos disappears quickly from water in acidic and alkaline water, but it is stable in neutral water when held in the dark. The compound, when in the presence of artificial light, disappears very rapidly. In a neutral solution, half of the initial amount of the compound degraded within 4 hours. • Breakdown in vegetation: In plants, the compound is absorbed through the roots and translocated to the leaves. It is broken down within the plant. The products of its breakdown are relatively persistent and can also inhibit cholinesterase [6]. Physical Properties: • Appearance: Fenamiphos is a colorless crystal in its pure form, or a tan waxy solid in the technical form [13]. • Chemical Name: ethyl 4-methylthio-m-tolyl isopropylphosphoramidate [13] • CAS Number: 22224-92-6 • Molecular Weight: 303.40 • Water Solubility: 700 mg/L @ 20 C [13] • Solubility in Other Solvents: s. in dichloromethane, isopropanol, and toluene [13] • Melting Point: 46 C (technical) [13] • Vapor Pressure: 0.12 mPa @ 20 C [13] • Partition Coefficient: Not Available • Adsorption Coefficient: 100 [19] Exposure Guidelines: • ADI: 0.005 mg/kg/day [38] of 4 5/12/00 2:05 PM