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EXTOXNET PIP -2,4-D Page 3 of 4 compound in eggs [7]. Ecological Effects: . Effects on birds: 2,4-D is slightly toxic to wildfowl and slightly to moderately toxic to birds. The LD50 is 1000 mg/kg in mallards, 272 mg/kg in pheasants, and 668 mg/kg in quail and pigeons [5- 7]. . Effects on aquatic organisms: Some formulations of 2,4-D are highly toxic to fish while others are less so. For example,the LC50 ranges between 1.0 and 100 mg/L in cutthroat trout, depending on the formulation used. Channel catfish had less than 10%mortality when exposed to 10 mg/L for 48 hours [1,9]. Green sunfish,when exposed to 110 mg/L for 41 hours, showed no effect on swimming response. Limited studies indicate a half-life of less than 2 days in fish and oysters [24]. Concentrations of 10 mg/L for 85 days did not adversely affect the survival of adult dungeness crabs. For immature crabs, the 96-hour LC50 is greater than 10 mg/L, indicating that 2,4-D is only slightly toxic. Brown shrimp showed a small increase in mortality at exposures of 2 mg/L for 48 hours [7,20]. . Effects on other organisms: Moderate doses of 2,4-D severely impaired honeybees brood production. At lower levels of exposure, exposed bees lived significantly longer than the controls. The honeybee LD50 is 0.0115 mg/bee [6,7]. Environmental Fate: . Breakdown in soil and groundwater: 2,4-D has low soil persistence. The half-life in soil is less than 7 days [21]. Soil microbes are primarily responsible for its disappearance [20]. Despite its short half-life in soil and in aquatic environments, the compound has been detected in groundwater supplies in at least five States and in Canada[20]. Very low concentrations have also been detected in surface waters throughout the U.S. [23]. . Breakdown in water: In aquatic environments, microorganisms readily degrade 2,4-D. Rates of breakdown increase with increased nutrients, sediment load, and dissolved organic carbon. Under oxygenated conditions the half-life is 1 week to several weeks [20]. . Breakdown in vegetation: 2,4-D interferes with normal plant growth processes. Uptake of the compound is through leaves, stems, and roots. Breakdown in plants is by a variety of biological and chemical pathways [10]. 2,4-D is toxic to most broad leaf crops, especially cotton, tomatoes, beets, and fruit trees [7]. Physical Properties: . Appearance: 2,4-D is a white powder[6]. . Chemical Name: (2,4-dichlorophenoxy)acetic acid [6] . CAS Number: 94-75-7 . Molecular Weight: 221.04 . Water Solubility: 900 mg/L @ 25 C (acid) [5] . Solubility in Other Solvents: ethanol v.s.; diethyl ether v.s.; toluene s.; xylene s. [6] . Melting Point: 140.5 C [6] . Vapor Pressure: 0.02 mPa @ 25 C (acid) [5] . Partition Coefficient: 2.81 [20] . Adsorption Coefficient: 20 (acid) [21] Exposure Guidelines: , http://extoxnet.orst.edu/pips/24-D.htm 5/8/2008