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The information in this profile may be out-of-date.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

Trifluralin

Trade and Other Names: Trade names include Crisalin, Elancolan, Flurene SE, Ipersan, L-36352, M.T.F., Su Seguro Carpidor, TR-10, Trefanocide, Treficon, Treflan, Tri-4, Trifluralina 600, Triflurex Trim, and Trust. The compound may be found in formulations with other herbicides.

Regulatory Status: Products containing trifluralin bear the Signal Words CAUTION or WARNING, depending on the type of formulation. This compound is a General Use Pesticide (GUP) in toxicity class III - slightly toxic. N-nitrosamine contaminant levels in trifluralin are required to be below 0.5 ppm, a level which EPA believes will result in no toxic effects.

Chemical Class: dinitroaniline compound

Introduction: Trifluralin is a selective, pre-emergence dinitroaniline herbicide used to control many annual grasses and broadleaf weeds in a large variety of tree fruit, nut, vegetable, and grain crops, including soybeans, sunflowers, cotton, and alfalfa. Pre-emergence herbicides are applied before weed seedlings sprout. Trifluralin should be incorporated into the soil by mechanical means within 24 hours of application. Granular formulations may be incorporated by overhead irrigation. Trifluralin is available in granular and emulsifiable concentrate formulations. The technical material is approximately 96% pure and the emulsifiable concentrate is about 45% pure.

Formulation: Granular formulations may be incorporated by overhead irrigation. Trifluralin is available in granular and emulsifiable concentrate formulations. The technical material is approximately 96% pure and the emulsifiable concentrate is about 45% pure.

Toxicological Effects:

• Acute toxicity: Pure trifluralin is practically nontoxic to test animals by oral, dermal, or inhalation routes of exposure [138]. The oral LD50 for technical trifluralin in rats is greater than 10,000 mg/kg, in mice is greater than 5000 mg/kg, and in dogs, rabbits, and chickens, is greater than 2000 mg/kg. However, certain formulated products that contain trifluralin may be more toxic than the technical material itself. For example, the oral LD50 for Treflan TR-10 in rats is greater than 500 mg/kg. The dermal LD50 for technical trifluralin in rabbits is greater than 2000 mg/kg. The 1-hour inhalation LC50 for technical trifluralin in rats is greater than 2.8 mg/L [58]. Nausea and severe gastrointestinal discomfort may occur after eating trifluralin. Trifluralin does not cause skin irritation. When applied to the eyes of rabbits, trifluralin produced slight irritation, which cleared within 7 days [8]. Skin sensitization (allergies) may occur in some individuals [8]. Inhalation may cause irritation of the lining of the mouth, throat, or lungs [8].
• Chronic toxicity: Prolonged or repeated skin contact with trifluralin may cause allergic dermatitis [8]. The administration of 25 mg/kg/day to dogs for 2 years resulted in no observed toxicity [58]. In another study of beagle dogs, toxic effects were observed at 18.75 mg/kg/day. These included decreased red blood cell counts and increases in methemoglobin, total serum lipids, triglycerides, and cholesterol [13]. Trifluralin has been shown to cause liver and kidney damage in other studies of chronic oral exposure in animals [139].
• Reproductive effects: The reproductive capacity of rats fed dietary concentrations of trifluralin as high as 10 mg/kg/day was unimpaired through four successive generations. Trifluralin administered to pregnant rabbits at doses as high as 100 mg/kg/day, and to rats at doses as high as 225 mg/kg/day, produced no adverse effect on either the mothers or offspring [58]. Loss of appetite and weight loss followed by miscarriages were observed when pregnant rabbits were fed high doses of 224 or 500 mg/kg/day. Fetal weight decreased and there was an increase in the number of fetal runts at the 500 mg/kg/day dosage [8]. It is unlikely effects on reproduction will be produced in humans at expected exposure levels.
• Teratogenic effects: No abnormalities were observed the offspring of rats fed doses as high as 10 mg/kg/day for four generations [58]. Studies in the rat and rabbit show no evidence that trifluralin is teratogenic. The highest doses tested in these studies were 1000 mg/kg/day in rats and 500 mg/kg/day in rabbits [138]. Trifluralin does not appear to be teratogenic.
• Mutagenic effects: No evidence of mutagenicity was observed when trifluralin was tested in live animals, and in assays using bacterial and mammalian cell cultures [138].
• Carcinogenic effects: In a 2-year study of rats fed 325 mg/kg/day, the highest dose tested, malignant tumors developed in the kidneys, bladder, and thyroid [138]. However, more data are needed to characterize its carcinogenicity.
• Organ toxicity: Liver, kidney, and thyroid damage appear to be the main toxic effects in chronic animal studies [139].

• Fate in humans and animals: Trifluralin is not readily absorbed into the bloodstream from the gastrointestinal tract; 80% of single oral doses administered to rats and dogs was excreted in the feces [8].

Ecological Effects:

• Effects on birds: Trifluralin is practically nontoxic to birds [63]. The LD50 in bobwhite quail is greater than 2000 mg/kg, as it is in female mallards and pheasants [63]. These values are for the technical product.
• Effects on aquatic organisms: Trifluralin is very highly toxic to fish and other aquatic organisms. The 96-hour LC50 is 0.02 to 0.06 mg/L in rainbow trout, and 0.05 to 0.07 mg/L in bluegill sunfish [37]. The 96-hour LC50 in channel catfish is approximately 1.4 to 3.4 mg/L [37]. Variables such as temperature, pH, life stage, or size may affect the toxicity of the compound. Trifluralin is highly toxic to Daphnia, a species of small freshwater crustacean, with a 48-hour LC50 of 0.5 to 0.6 mg/L [140]. The compound shows a moderate tendency to accumulate in aquatic organisms.
• Effects on other organisms: At exposure levels well above permissible application rates (100 mg/kg), trifluralin has been shown to be toxic to earthworms. However, permitted application rates will result in soil residues of approximately 1 ppm trifluralin, a level that had no adverse effects on earthworms [140]. It is nontoxic to bees [1].

Environmental Fate:

• Breakdown in soil and groundwater: Trifluralin is of moderate to high persistence in the soil environment, depending on conditions. Trifluralin is subject to degradation by soil microorganisms. Trifluralin remaining on the soil surface after application may be decomposed by UV light or may volatilize. Reported half-lives of trifluralin in the soil vary from 45 to 60 days [11] to 6 to 8 months [1]. After 6 months to 1 year, 80 to 90% of its activity will be gone [8]. It is strongly adsorbed on soils and nearly insoluble in water [11]. Because adsorption is highest in soils high in organic matter or clay content and adsorbed herbicide is inactive, higher application rates may be required for effective weed control on such soils [58,8]. Trifluralin has been detected in nearly 1% of the 5590 wells tested. However, it has been detected at very low concentrations, typically ranging from 0.002 ug/L to 15 ug/L [8].
• Breakdown in water: Trifluralin is nearly insoluble in water [1]. It will probably be found adsorbed to soil sediments and particulates in the water column.
• Breakdown in vegetation: Trifluralin inhibits the growth of roots and shoots when it is absorbed by newly germinated weed seedlings [58]. Trifluralin residues in crop plants will occur only in root tissues which are in direct contact with contaminated soil. Trifluralin is not translocated into the leaves, seeds, or fruit of most plants. On most crops, trifluralin applied to the leaves has no effect, but on certain crops, such as tobacco and summer squash, leaf distortion may occur [58].

Physical Properties:

• Appearance: Trifluralin is an odorless, yellow-orange crystalline solid [1].
• Chemical Name: a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine [1]
• CAS Number: 1582-09-8
• Molecular Weight: 335.50
• Water Solubility: <1 mg/L @ 27 C [1]
• Solubility in Other Solvents: s. in organic solvents such as acetone and xylene [1]
• Melting Point: 48.5-49 C [1]
• Vapor Pressure: 13.7 mPa @ 25 C [1]
• Partition Coefficient: 5.0719 @ pH 7 and 25 C [1]
• Adsorption Coefficient: 8000 [11]

Exposure Guidelines:

• ADI: Not Available
• MCL: Not Available
• RfD: 0.0075 mg/kg/day [13]
• PEL: Not Available
• HA: 0.005 mg/L (lifetime) [139]
• TLV: Not Available

Basic Manufacturer:

DowElanco
9330 Zionsville Road
Indianapolis, IN 46268-1054

• Phone: 317-337-7352
• Emergency: 800-258-3033
  

References:

References for the information in this PIP can be found in Reference List Number 10

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.