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The information in this profile may be out-of-date.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

Fluometuron

Trade and Other Names: Trade names include C-2059, Ciba-2059, Cotoran, Cotorex, Cottonex, Flo-Met, Higalcoton, Lanex, Pakhtaran.

Regulatory Status: Fluometuron is a practically nontoxic compound in EPA toxicity class II due to its potential to cause skin sensitization. Labels of fluometuron products must bear the Signal Word WARNING. Fluometuron is a General Use Pesticide (GUP).

Chemical Class: urea

Introduction: Fluometuron is a selective herbicide which acts on susceptible plants by inhibiting photosynthesis. Fluometuron is registered by EPA exclusively for use on cotton and sugarcane. It can be applied pre-emergence, for weed control before planting, or post-emergence, after target crops and weeds come up, and may have residual activity for several months. Fluometuron is available in liquid, dry flowable, and wettable powder formulations.

Formulation: Fluometuron is available in liquid, dry flowable, and wettable powder formulations.

Toxicological Effects:

• Acute toxicity: Fluometuron is practically nontoxic by ingestion with a reported oral LD50 of 6416 to 8900 mg/kg in rats [4,8]. Via the dermal route, it is also practically nontoxic; the dermal LD50 is greater than 2000 mg/kg in rats and greater than 10,000 mg/kg in rabbits [4,7]. Fluometuron is a mild skin irritant and causes skin sensitization in guinea pigs. It may cause corneal opacity in test animals [33]. It is irritating to the mucous membrane lining the skin, gastrointestinal tract, and respiratory system. The inhalation LC50 in rats is greater than 2 mg/L, indicating moderate to low toxicity by this route [4]. While there have been no reports of cases of fluometuron poisoning in humans, this herbicide is considered a mild inhibitor of cholinesterase. Cholinesterase inhibition was observed in guinea pigs exposed by inhalation to about 0.6 mg/L for 2 hours [33]. Examination of rats used for LD50 testing revealed increased brain weight [17]. Other symptoms of fluometuron poisoning in rats include muscular weakness, tearing or watery eyes, extreme exhaustion, and collapse [17].
• Chronic toxicity: Rats were fed 7.5, 75, or 750 mg/kg/day for 90 days. At the highest dose, decreased body weight and congestion in the spleen, adrenals, liver, and kidneys, as well as abnormalities in red blood cells were evident [8,17]. When doses of 1.5, 15 or 150 mg/kg/day were fed to puppies for 90 days, congestion of the liver, kidneys, and spleen occurred at the highest dose. No effects were seen at 15 mg/kg/day [8,17]. Prolonged or repeated exposure to fluometuron may cause conjunctivitis or skin sensitization [4,8].
• Reproductive effects: There were no reproductive effects due to fluometuron seen in pregnant rats given doses as high as 50 mg/kg/day during gestation, even though toxic effects in the mother were observed [4,8]. Pregnant rabbits were given doses of 50, 500, or 1000 mg/kg/day by stomach tube during days 6 through 19 of gestation. An increase in the number of resorbed fetuses was found at all treatment doses. Reduction in maternal body weight and food consumption occurred at doses of 500 and 1000 mg/kg/day [17]. The evidence indicates that fluometuron will not cause reproductive effects in humans at expected levels of exposure.
• Teratogenic effects: Some secondary developmental effects were seen in the progeny of rats and rabbits receiving 100 mg/kg/day during gestation [4,8]. These higher dose data indicate that teratogenic effects are not likely in humans at expected exposure levels.
• Mutagenic effects: In various tests for mutagenicity and genotoxicity, fluometuron has not shown activity. These include the Ames mutagenicity assay, the Chinese hamster ovary cell culture assay for chromosome aberration, and DNA repair inhibition tests in rat liver and human fibroblast cell lines [4]. It reportedly did show some interference with DNA synthesis in the testes of mice given a single oral dose of 2000 mg/kg [17]. Based on these studies, fluometuron does not appear to be mutagenic.
• Carcinogenic effects: Mice that were given oral doses of 87 mg/kg/day for 2 years showed evidence of liver tumors and leukemia, a condition characterized by uncontrolled growth in the number of white-blood cells [4]. Another study showed increased liver cell tumor incidence in male mice, but carcinogenic effects were not observed in female mice or in rats of either sex [8,17]. The available evidence in inconclusive, but suggests that carcinogenic effects in humans is not likely.
• Organ toxicity: Target organs of fluometuron as determined in animal studies include brain, spleen, adrenals, liver, and kidneys, and red blood cells.

• Fate in humans and animals: Fluometuron is absorbed only slowly into the body from the gastrointestinal tract. At 72 hours after rats were given oral doses of 50 mg/kg fluometuron, 15% of the dose was excreted in the urine and 49% was excreted unchanged in the feces [17]. At the same time, fluometuron or its metabolites were detected in the rats' livers, kidneys, adrenal gland, pituitary gland, red blood cells, blood plasma, and spleen, with the highest concentration found in red-blood cells [17].

Ecological Effects:

• Effects on birds: Fluometuron is practically nontoxic to birds; the reported acute oral LD50 values for fluometuron are greater than 2150 mg/kg in bobwhite quail and 2974 mg/kg in mallard ducks [4,8]. The reported 5- to 8-day dietary LC50 values for fluometuron were greater than 5620 ppm in bobwhite quail, 4500 ppm in mallard ducks, 3150 in ring-neck pheasant, and 4620 ppm in Japanese quail [4,8].
• Effects on aquatic organisms: Fluometuron is slightly toxic to fish. The reported 96-hour LC50 of technical fluometuron is 30 mg/L in rainbow trout, 48 mg/L in bluegill sunfish, 170 mg/L in carp, and 55 mg/L in catfish. In catifsh, tissue concentrations in whole fish were 40 times that of the ambient water, indicating low capacity for bioaccumulation [8]. The reported 48 hour LC50 for fluometuron in Daphnia (water flea) is 54 mg/L [4], indicating slight toxicity to aquatic invertebrates.
• Effects on other organisms: Fluometuron is relatively nontoxic to bees [8].

Environmental Fate:

• Breakdown in soil and groundwater: Fluometuron is moderately to highly persistent in the soil environment, with a reported field half-life of 12 to 171 days [19]. A representative field half-life under most conditions is estimated to be 85 days [19]. Breakdown in the soil environment occurs mainly through photodegradation, when there is little rainfall after application, and by microbial breakdown otherwise. Fluometuron is soluble in water, and poorly bound to most soils. This suggests that it would be mobile in most soils, but in field studies in California and Georgia no residues were detected below 12 inches [4]. In addition, fluometuron was not found in groundwater during a national survey [11].
• Breakdown in water: Fluometuron may be highly persistent in the water environment as well. The half-life of fluometuron in water is 110 to 144 weeks [11]. It is stable at pH values ranging from 1 to 13, at 20 C [3]. However, exposure of 10 ppm aqueous solutions of fluometuron to natural sunlight resulted in 88% decomposition in 3 days, with a half-life of 1.2 days [4].
• Breakdown in vegetation: Fluometuron is more readily absorbed by roots from soil application than by leaves from foliar application [4]. The addition of a surfactant or nonphytotoxic oil to spray solutions improves the absorption of fluometuron by leaves [4]. The rate at which it is absorbed, translocated, and subsequently broken down, (or metabolized) differs with various plant species [4]. An understanding of these differences is important in determining the tolerance or susceptibility of plants and weeds to this chemical.

Physical Properties:

• Appearance: Fluometuron is a white to tan powder or crystalline material with an amine-like odor [7].
• Chemical Name: 1,1-dimethyl-3-(a,a,a-trifluoro-m-tolyl) urea [7]
• CAS Number: 2164-17-2
• Molecular Weight: 232.29
• Water Solubility: 105 mg/L @ 20 C [7]
• Solubility in Other Solvents: s.s in acetone, chloroform, methanol, hexane, and organic solvents [16]; s.s in hexane [7]
• Melting Point: 163-164 C [7]
• Vapor Pressure: 0.067 mPa @ 20 C [7]
• Partition Coefficient: 2.2330 [7]
• Adsorption Coefficient: 100 [19]

Exposure Guidelines:

• ADI: Not Available
• MCL: Not Available
• RfD: 0.00025 mg/kg/day [31]
• PEL: Not Available
• HA: 0.09 mg/L (lifetime) [17]
• TLV: Not Available

Basic Manufacturer:

Ciba-Geigy Corporation
P.O. Box 18300
Greensboro, NC 27419-8300

• Phone: 800-334-9481
• Emergency: 800-888-8372
  
  

References:

References for the information in this PIP can be found in Reference List Number 9

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.