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EXTOXNET PIP - 2,4-D hup://ace.ace.orst.edu/info/ex~oxneUpips/24-D.h~m • • 2,4-Din drinking water from birth to maturity had very low levels of the compound in eggs [7]. Ecological Effects: Effects on birds: 2,4-D is slightly toxic [o 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%o mortality when exposed to ]0 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 ahalf-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/I,, 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 Slates 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 [o 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) [2l] Exposure Guidelines: 3 0(4 11/18/98 10:38 AM