EPTC

Trade and Other Names: Trade names include Alirox, Eptam, Eradicane, Eradicane Extra, Genep, Genep Plus, and Shortstop.

Regulatory Status: EPTC is a slightly toxic compound in EPA toxicity class III. It is a General Use Pesticide (GUP); labels for products containing EPTC must bear the Signal Word CAUTION.

Chemical Class: thiocarbamate

Introduction: EPTC is a selective thiocarbamate herbicide used for control of annual grassy weeds, perennial weeds, and some broadleaf weeds in beans, forage legumes, potatoes, corn, and sweet potatoes. It is usually applied preemergence, that is before weed seeds germinate, and is usually incorporated into the soil immediately after application either mechanically or by overhead irrigation. EPTC is available as emulsifiable concentrates and granular formulations.

Formulation: EPTC is available as emulsifiable concentrates and granular formulations.

Toxicological Effects:

• Acute toxicity: EPTC is slightly toxic via ingestion, with reported oral LD50 values of 1632 mg/kg in rats, 3160 mg/kg in mice, 112 mg/kg in cats, and 2460 mg/kg in rabbits [4,7]. It is slightly toxic via the dermal route as well, with reported dermal LD50 values of 5000 mg/kg in rabbits and 3200 mg/kg in rats [7]. The reported 1-hour inhalation LC50 in rats of 31.56 mg/L indicates slight toxicity by this route [3]. It is a mild to moderate skin irritant in rabbits, a weak skin sensitizer in guinea pigs, and a mild eye irritant in rabbits [7]. EPTC is a cholinesterase inhibitor. Early symptoms of cholinesterase inhibition are blurred vision, fatigue, headache, vertigo, nausea, pupil contraction, abdominal cramps, and diarrhea. Severe inhibition of cholinesterase may cause excessive sweating, tearing, slowed heartbeat, giddiness, slurred speech, confusion, excessive fluid in the lungs, convulsions, and coma. Workers subjected to inhalation exposure to EPTC experienced headaches, nausea, general malaise, and impaired working capacity. Animals poisoned in experimental tests displayed excitement, salivation, tearing, spasmodic winking, and depression (28,29).
• Chronic toxicity: In a 16-week study of dogs fed 45 mg/kg/day, effects of brain cholinesterase inhibition and gastric mucosal changes were reported [28]. In a 54-week feeding study of EPTC no effects were observed at 20 mg/kg/day [28]. In a two-generation study with rats fed 10 or 40 mg/kg/day, technical EPTC caused degeneration of tissues of the spinal chord, nerves, muscle, and heart tissue. No evidence of these effects was seen in a survey of workers who produced and formulated technical EPTC [29].
• Reproductive effects: In a study where oral doses of 30, 100 or 300 mg/kg/day were administered on days 6 to 15 of pregnancy, maternal mortality and decreased weight gain and food consumption occurred at the highest dose. Decreased fetal body weight and increased loss of fetuses occurred at 100 and 300 mg/kg/day [27]. It is not likely that EPTC will cause reproductive effects in humans under normal circumstances.
• Teratogenic effects: No effects were observed in a teratogenic study in which rats were given 300 mg/kg/day [7,27]. The available evidence suggests that EPTC is not teratogenic.
• Mutagenic effects: EPTC was not mutagenic when tested in a series of assays with microbial and human cell culture lines [7,29].
• Carcinogenic effects: In a 2-year feeding and oncogenicity study of EPTC in mice no excess tumors were seen at doses of up to 20 mg/kg/day [7]. The available evidence suggests that EPTC is not carcinogenic.
• Organ toxicity: In lifetime studies with animals, the target organs of technical EPTC toxicity were nerves, muscle, and heart tissue [30].

• Fate in humans and animals: In rats, low oral amounts of EPTC (approximately 0.6 mg) were mainly eliminated via expired air, and much smaller amounts were eliminated via the urine and feces. When the amount was increased to 100 mg, the relative proportion excreted via urine and feces was increased [31].

Ecological Effects:

• Effects on birds: EPTC is slightly toxic to relatively nontoxic to birds. The oral LC50 for technical EPTC in bobwhite quail is 20,000 ppm for a 7-day feed treatment [31].

• Effects on aquatic organisms: EPTC is slightly toxic to fish and aquatic organisms. The reported 96-hour LC50 values for EPTC are 19 mg/L in rainbow trout, 27 mg/L in bluegill sunfish, 17 mg/L in mosquito fish, 17 mg/L in cuttthroat trout, and 16 mg/L in lake trout [3,7,16]. The 24-hour LC50 in the blue crab is greater than 20 mg/L [7]. Bioconcentration values for fish range from 37 to 190 times the ambient water concentration indicating that the compound will not significantly accumulate in these organisms [30].
• Effects on other organisms: EPTC is practically nontoxic to bees, with a reported LD50 of 0.011 mg per bee [3].

Environmental Fate:

• Breakdown in soil and groundwater: EPTC is of low persistence in the soil environment, with reported field half-lives of 6 to 32 days; a representative field half-life for most soil regimes is 6 days [20]. It is not strongly bound to soils, especially those lower in organic matter and clay content [7,20]. Microbial breakdown and volatilization are the main mechanisms by which EPTC is lost from soils [20]. Due to its short half-life, it is not a threat to groundwater.
• Breakdown in water: There is little chance that it will enter surface waters, due to its short half-life.
• Breakdown in vegetation: EPTC is readily absorbed by the roots of plants and translocated upward to the leaves and stems. EPTC is rapidly metabolized by plants to carbon dioxide and naturally occurring plant constituents [7,30].

Physical Properties:

• Appearance: EPTC is a colorless to pale yellow liquid with an aromatic odor [3].
• Chemical Name: s-ethyl dipropylthiocarbamate [3]
• CAS Number: 759-94-4
• Molecular Weight: 189.32
• Water Solubility: 375 mg/L @ 25 C [3]
• Solubility in Other Solvents: v.s. in acetone, ethyl alcohol, kerosene, methyl isobutyl ketone, and xylene [3]
• Melting Point: Not Available
• Vapor Pressure: 4700 mPa @ 25 C [3]
• Partition Coefficient: 3.2041 [3]
• Adsorption Coefficient: 200 [20]

Exposure Guidelines:

• ADI: Not Available
• MCL: Not Available
• RfD: Not Available
• PEL: Not Available
• HA: Not Available
• TLV: Not Available

Basic Manufacturer:

Zeneca Ag Products
1800 Concord Pike
Wilmington DE 19897

• Phone: 800-759-4500
• Emergency: 800-759-2500
  

Original Report at:  E X T O X N E T

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