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The information in this profile may be out-of-date. It was last revised in 1996. EXTOXNET no longer updates this information, but it may be useful as a reference or resource.

Please visit the National Pesticide Information Center (NPIC) to find updated pesticide fact sheets. If you don't find a fact sheet related to your question, feel free to call 1-800-858-7378. NPIC is open five days a week from 8:00am to 12:00pm Pacific Time.

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E X T O X N E T

Extension Toxicology Network

Pesticide Information Profiles

A Pesticide Information Project of Cooperative Extension Offices of Cornell University, Oregon State University, the University of Idaho, and the University of California at Davis and the Institute for Environmental Toxicology, Michigan State University. Major support and funding was provided by the USDA/Extension Service/National Agricultural Pesticide Impact Assessment Program.

EXTOXNET primary files maintained and archived at Oregon State University

Revised June 1996

Triallate

Trade and Other Names: Trade names for triallate include Avadex BW, Buckle, Carbamothoic acid, CP 23426, Dipthal, Far-Go, Showdown, and TDTC Technical.

Regulatory Status: Triallate is a General Use Pesticide (GUP). It is classified as toxicity class III - slightly toxic. Formulations of triallate bear the Signal Word CAUTION.

Chemical Class: thiocarbamate

Introduction: Triallate belongs to the thiocarbamate chemical class. It is a pre-emergence selective herbicide used to control grass weeds in field and pulse crops. It is used selectively to control wild oats, black grass, and annual meadow grass in barley, wheat, peas, lentils, rye, maize, beets, brassicas, carrots, and onions. Depending on the crop that is treated, the herbicide is incorporated in the soil before or after planting. Triallate is available as emulsifiable concentrate and granular formulations.

Formulation: Triallate is available as emulsisfiable concentrate and granular formulations. Toxicological Effects:

• Acute toxicity: Technical triallate is slightly toxic by ingestion and practically nontoxic via dermal exposure or inhalation [4]. The oral LD50 for technical triallate in rats is 800 to 2165 mg/kg, and in mice is 930 mg/kg [3,4]. The oral LD50 in rats for emusifiable concentrate formulations is 2700 mg/kg, and for granular formulations is greater than 12,000 mg/kg [7]. The dermal LD50 for technical triallate is 8200 mg/kg in rabbits, and 3500 mg/kg in rats. The inhalation 4-hour LC50 in cats is 0.4 mg/L [4]. In rats fed triallate at doses of 50 to 2000 mg/kg, abnormal behavior was observed at doses of 100 mg/kg and above. No changes in nerve tissue occurred. At doses of 600 mg/kg and above, death and reduced body weight occurred [37]. Sheep may be poisoned by 300 mg/kg of triallate, with symptoms of depression, lack of appetite, mouth watering, weakness, and convulsions [38]. Inhalation exposure to large amounts of thiocarbamates may cause itching, scratchy throat, sneezing, and coughing [7]. Triallate is moderately irritating to the skin and is a mild eye iritant. Tests on guinea pigs indicate that technical triallate does not cause allergic skin reactions [38]. Although triallate is a carbamate, it does not inhibit cholinesterase activity. No symptoms occurred, and cholinesterase activity was not affected in rats fed single doses of 1500 and 3000 mg/kg [4].
• Chronic toxicity: Prolonged or repeated exposure to triallate may cause symptoms similar to those caused by acute exposure. Oral doses of 100 mg/kg/day triallate to hamsters for 22 months resulted in decreased body weight gain, changes in blood chemistry, slight anemia, increased liver weights, and decreased spleen weights. Mice fed 3 and 12.5 mg/kg/day triallate for 2 years exhibited increased liver and heart weights, changes in the liver and spleen, and mineralization in the brain and cornea. No adverse effects were observed in dogs fed 1.5, 5, and 15 mg/kg/day triallate for 2 years [37,38]. At high dose levels in subchronic exposure studies, neurological effects have been observed in rats. Rat deaths at these high levels were probably due to a variety of systemic effects such as liver and stomach pathological changes, decreased food consumption, and loss of body weight. Neurological effects were not observed in rats at doses of 50 mg/kg/day or below [37,38].
• Reproductive effects: Reduced body and pup weights, reduced pregnancy rate and length, reduced pup survival, and effects on other reproductive parameters occurred when rats were fed 30 mg/kg/day triallate during mating, pregnancy, and nursing for two successive generations [37,38]. This suggests that triallate can cause reproductive effects at high doses.
• Teratogenic effects: No birth defects were observed in the offspring of rabbits given triallate doses of 5, 15, and 45 mg/kg/day on days 6 to 28 of pregnancy. No birth defects were observed in the offspring of rats given doses of 10, 30, 90 mg/kg/day on days 6 to 20 of pregnancy. In both of these studies, the highest dose administered caused poisoning symptoms in both the mothers and their offspring [38]. These data indicate that triallate is not teratogenic.
• Mutagenic effects: No genetic changes occurred in tests using live animals (fruit flies, hamsters, and mice). In tests using bacterial and animal cell cultures, both positive and negative results have been reported [37,38]. This suggests that triallate is either nonmutagenic or weakly mutagenic.
• Carcinogenic effects: When fed dietary doses of about 2.5, 7.5 and 30 mg/kg/day technical triallate over a long time, the incidence of liver tumors increased in a strain of mice normally prone to spontaneous production of liver tumors. Several other long-term feeding studies showed no incidence of tumors [37]. Triallate did not produce tumors in rats fed up to 12.5 mg/kg/day for 2 years [38]. No tumors appeared when hamsters were fed dietary doses of up to 100 mg/kg triallate for 22 months [37]. These data indicate that triallate is not carcinogenic [39].
• Organ toxicity: Changes in the cellular processes of the brain, liver and spleen were observed in pigs given triallate [4]. Studies on other species have indicated the thymus, kidneys and reproductive organs are potential targets as well.
• Fate in humans and animals: In general, thiocarbamates, the chemical class in which triallate is included, are rapidly absorbed into the bloodstream from the gastrointestinal tract, readily broken down into metabolites, and then excreted by treated animals. It is rarely possible to detect thiocarbamates in the blood [40]. A single oral dose of 500 mg/kg of triallate was rapidly absorbed from the gastrointestinal tract of rabbits. It was then found to be present in all organs tested within 15 to 20 minutes after dosing. The largest amount of the herbicide accumulated in the liver, lungs, kidneys, and spleen. All traces were gone by the 7th day. Triallate was reported to be completely eliminated from the body of rabbits within 7 to 10 days [4]. The meat of sheep poisoned by approximately 300 mg/kg of triallate had detectable traces 84 days later in cold storage. No traces of the herbicide were detected in the eggs, meat, or internal organs of hens fed 0 to 4% of an LD50 dose [4,38].

Ecological Effects:

• Effects on birds: Triallate is slightly toxic to relatively nontoxic to birds. The acute oral LD50 for triallate in bobwhite quail is 2251 mg/kg. The 8-day dietary LD50 is greater than 5000 ppm in both mallards and bobwhite quail [7,38].
• Effects on aquatic organisms: Triallate is highly toxic to fish and other aquatic organisms. The 48-hour EC50 in Dapnia magna, a small freshwater crustacean, is 0.06 to 0.10 mg/L for the 95% technical material and the LC50 is 0.05 to 0.07 mg/L for the 46% emulsifiable concentrate [17]. The 96-hour LC50 in algae is 0.12 mg/L [38]. The 96-hour LC50 for technical material has been reported as 0.62 mg/L in rainbow trout (1.0 mg/L for the emulsifiable concentrate), and 1.7 mg/L in channel catfish (1.1 mg/L for the emulsifiable concentrate) [17]. A 96-hour LC50 of 1.3 mg/L is reported in bluegill [38]. When technical triallate concentrations were measured in bluegill sunfish over a 7-week period, marked bioaccumulation occurred. The concentration in the fish was 1600 times the ambient water concentration. However, after 2 weeks in water without triallate, the compound was nearly completely eliminated by the fish [38].
• Effects on other organisms: Triallate is nontoxic to bees [3].

Environmental Fate:

• Breakdown in soil and groundwater: Triallate has a moderate persistence in the soil environment. It adsorbs strongly to loam and clay soils and is not readily dissolved in water. This indicates that triallate is not likely to move through the soil, even though it has an average soil half-life of 82 days [7,20]. However, if there is significant moisture and/or a low level of organic matter in the soil, leaching and groundwater contamination may be possible. EPA suggests that triallate does not pose a threat to the environment due to leaching because it is generally used where the water table is relatively low [39]. Triallate is reported to be degraded in soil primarily by soil microbes [7]. Plants also degrade triallate, lessening its potential to accumulate in the soil [39]. If applied to the soil surface at high temperatures, without incorporation into the soil, triallate can be lost to the atmosphere through volatilization. Its volatility increases with soil water content [39]. Triallate must be incorporated into the soil after application to prevent its loss from soil at high temperatures. Triallate can persist into the next growing season, especially in colder climates in which it is less likely to be broken down [39]. Photodecomposition, or breakdown in the presence of sunlight, is considered an insignificant method of degradation for triallate [4].
• Breakdown in water: Triallate is stable to ultraviolet degradation and will probably be found adsorbed to suspended sediment in the water column or in hydrosoils due to its slight water solubility and its ability to bind to particulates [7]. Typical breakdown times in hydrosoils may be longer than in terrestrial systems due to lower oxygen availability for microbial degradation.
• Breakdown in vegetation: Studies indicate that triallate does not bioaccumulate in plants. Triallate is absorbed and metabolized by plants [39].

Physical Properties:

• Appearance: Triallate is an amber, oily liquid [3].
• Chemical Name: S-(2,3,3-trichloro-2-propenyl)bis(1-methylethyl) carbamothioate [3]
• CAS Number: 2303-17-5
• Molecular Weight: 304.66
• Water Solubility: 4 mg/L @ 25 C [3]
• Solubility in Other Solvents: s. in acetone, ether, ethyl alcohol, heptane, benzene, ethyl acetate, and most organic solvents [3]
• Melting Point: 29-30 C [3]
• Vapor Pressure: 16 mPa @ 25 C [3]
• Partition Coefficient: Not Available
• Adsorption Coefficient: 2400 [20]

Exposure Guidelines:

• ADI: Not Available
• MCL: Not Available
• RfD: 0.013 mg/kg/day [27]
• PEL: Not Available
• HA: Not Available
• TLV: Not Available

Basic Manufacturer:

Monsanto Company
800 N. Lindbergh Blvd.
St. Louis, MO 63167

• Phone: 314-694-6640
• Emergency: 314-694-4000
  

References:

References for the information in this PIP can be found in Reference List Number 4

DISCLAIMER: The information in this profile does not in any way replace or supersede the information on the pesticide product labeling or other regulatory requirements. Please refer to the pesticide product labeling.