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EXTOXNET PIP-SIMn7.INE http://ace.orst.edu/cgi-bin/mt's/01/pips/siniazine.htm days after administration [16]. Ecological Effects: • Effects on birds: Simazine is practically nontoxic to birds [6,16]. The reported LD50 values in mallard and Japanese quail are >4600 mg/kg and 1785 mg/kg, respectively [6]. The acute dietary LD50 values in hens and pigeons are both greater than 5000 ppm [2]. The 8-day dietary LC50 in bobwhite quail is >5260 ppm and in mallard ducks is >I0,000 ppm [6,15]. • Effects on aquatic organisms: Simazine is slightly to practically nontoxic to aquatic species [6,15]. The 96-hour LC50 for simazine is>100 mg/L [46] in rainbow trout, 100 mg/L (wettable powder) in bluegill sunfish, 0.100 mg/L in fathead minnows [46], as well as carp [2]. It may be more toxic to Daphia and stoneflies [46]. A 96-hour LC50 of>3.7 mg/L is reported in oysters [15]. • Effects on other organisms: While many mammals may be insensitive to simazine [16], sheep and cattle are especially sensitive [3]. Simazine is nontoxic to bees [6,16]. A soil LC50 in earthworms of>1000 mg/kg has been reported [16]. Environmental Fate: • Breakdown in soil and groundwater: Simazine is moderately persistent with an average field half-life of 60 days [20]. Soil half-lives of 28-149 days have been reported [20]. Residual activity may remain for a year after application (2 to 4 kg/ha) in high pH soils. Simazine is moderately to poorly bound to soils [20]. It does, however, adsorb to clays and mucks. Its low water solubility, however, makes it less mobile, limiting its leaching potential [15]. Simazine has little, if any, lateral movement in soil, but can be washed along with soil particles in runoff. Simazine is subject to decomposition by ultraviolet radiation, but this effect is small under normal field conditions. Loss from volatilization is also insignificant. In soils, microbial activity probably accounts for decomposition of a significant amount of simazine in high pH soils. In lower pH soils, hydrolysis will occur [15]. Simazine residues have been detected in groundwater in at least 16 states. The range was from 0.00002 mg/L to 0.0034 mg/L [23]. • Breakdown in water: The average half-life of simazine in ponds where it has been applied is 30 days, with the actual half-life dependent on the level of algae present, the degree of weed infestation, and other factors [15]. Simazine may undergo hydrolysis at lower pH. It does not readily undergo hydrolysis in water at pH = 7 [15]. • Breakdown in vegetation: Plants absorb simazine mainly through the roots, with little or no foliar penetration. From the roots, it is translocated upward to the stems, leaves, and growing shoots of the plant [6,15]. It acts to inhibit photosynthesis [6,15]. Resistant plants readily metabolize simazine. Plants that are sensitive to simazine accumulate it unchanged [6]. It is possible that livestock or wildlife grazing on these plants could be poisoned. Physical Properties: • Appearance: Simazine is a white or colorless crystalline solid [6]. • Chemical Name: 6-chloro-N2,N4-diethyl-1,3,5-triazine-2,4-diamine [6] • CAS Number: 122-34-9 • Molecular Weight: 201.70 • Water Solubility: 5 mg/L @ 20 C [6] • Solubility in Other Solvents: s. in methanol, chloroform, and diethyl ether [6]; s.s. in pentane [6] • Melting Point: 225-227 C [6] • Vapor Pressure: 0.000810 mPa @ 20 C [6] 3 of*4 S/I I/00 4 11 I'M