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EXTOXNET PIP -DINOSEB Page 3 of 4 <br /> "Nov <br /> Ecological Effects: <br /> . Effects on birds: The compound is very highly toxic to birds, with reported acute oral LD50 <br /> values between 7 and 9 mg/kg [8]; its reported 5-to 8-day dietary LC50 ranges from 409 ppm in <br /> quail to 515 ppm in pheasants [8]. It thus has the potential to negatively impact local pheasant and <br /> songbird populations. <br /> . Effects on aquatic organisms: Dinoseb is highly toxic to fish,with reported 96-hour LC50 <br /> values ranging from 44 ug/L in lake trout to 118 ug/L in catfish [8]. Other 96-hour LC50 values <br /> are 100 ug/L in coho salmon and 67 ug/L in cutthroat trout [8,37]. It is more toxic to fish in acidic <br /> water than in neutral or alkaline water [37]. Dinoseb has caused fish kills in small Scottish streams <br /> when washed from fields by rain [88]. The bioconcentration factor is 135 (86). Dinoseb is rapidly <br /> taken up by fish,but is is rapidly eliminated from exposed fish if placed in clean water. Dinoseb, <br /> thus, does not pose a significant risk for bioaccumulation [84]. <br /> . Effects on other organisms: Dinoseb is toxic to bees [1]. <br /> Environmental Fate: <br /> . Breakdown in soil and groundwater: Dinoseb is of low persistence regardless of the form <br /> (phenolic or salt). Reported field half-lives for both types of dinoseb range from 5 to 31 days [53]. <br /> An overall representative value is estimated to be 20 tp 30 days in most circumstances, although <br /> persistence may be much longer in the vadose zone [9]. Photodegradation and microbial <br /> breakdown may play roles in the breakdown of dinoseb in the soil environment,but volatilization <br /> should not be a significant route of loss [9]. The phenolic form of dinoseb is slightly soluble in <br /> water and moderately sorbed by most soils [53]. Studies have shown soil sorption capacity to be <br /> much greater at lower pH values [9]. It thus should present only a moderate risk to groundwater. <br /> On the other hand, the ammonium and amine salt forms of dinoseb are much more water-soluble <br /> and much less strongly bound to soils [8]. These may pose a significant risk to groundwater. Over <br /> a 10-year period, dinoseb was found to be one of three particularly persistent contaminants in <br /> Ontario wells [8]. Entry to the wells was due to spills of concentrated and dilute herbicide, drift <br /> during spraying, and from storm runoff. Well water concentrations ranged from 0.05 to 5000 ug/L <br /> in these wells, and removal of dinoseb proved to be very difficult [9]. <br /> . Breakdown in water: Photodegradation may occur in surface waters,but hydrolysis is essentially <br /> negligible [9]. Dinoseb has been found in streams at about 5 ug/L [8]. <br /> . Breakdown in vegetation: Dinoseb persists on treated crop soils for 2 to 4 weeks,under average <br /> conditions of use [8]. <br /> Physical Properties: <br /> . Appearance: Dinoseb is a dark reddish-brown solid or dark orange viscous liquid, depending on <br /> the temperature [1]. <br /> . Chemical Name: 2-(sec-butyl)-4,6-dinitrophenol [1] <br /> . CAS Number: 88-85-7 <br /> . Molecular Weight: 240.22 <br /> . Water Solubility: 52 mg/L @ 20 C [1] <br /> . Solubility in Other Solvents: v.s. in alcohol, ethanol, and heptane; s. in spray oil and in most <br /> organic solvents and oils [1] <br /> . Melting Point: 32-42 C [1] <br /> . Vapor Pressure: 6.7 mPa @ 25 C [53] <br /> . Partition Coefficient: Not Available <br /> . Adsorption Coefficient: 30 (estimated) [53] <br /> http://extoxnet.orst.edu/pips/dinoseb.htm 3/24/2008 <br />