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Fluometuron. 1994 Pesticide
Information Profile. EXTOXNET.
http://pmep.cce.cornell.edu/profiles/extoxnet/dienochlor-glyphosate/fluometuron-ext.html
A Pesticide Information Project of Cooperative Extension Offices
of Cornell University, Michigan State University, Oregon State University, and
University of California at Davis. Major support and funding was provided by
the USDA/Extension Service/National Agricultural Pesticide Impact Assessment
Program.
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Pesticide
Information
Profile |
Fluometuron
Publication Date: 3/94 |
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TRADE OR OTHER NAMES
Trade names include C-2059, Cotoran, Cotorex, Cottonex, Ciba-2059, Higalcoton,
Lanex, Pakhtaran.
REGULATORY STATUS
Fluometuron is registered by the U.S. Environmental Protection Agency (EPA) for
use on cotton and sugarcane (2). It may only be manufactured
into formulations intended for herbicide use on these crops (13).
Container labels of fluometuron products must bear the signal word "WARNING"
(1). Check with specific state regulations for local restrictions
that may apply.
INTRODUCTION
Fluometuron is a selective herbicide used to control weeds in cotton (16).
It acts on susceptible plants by inhibiting photosynthesis. It can be applied
preemergence, for weed control before planting, or postemergence, after target
crops and weeds come up (15). It has prolonged residual action
of two to five months (6). Fluometuron is available as liquid,
dry flowable, and wettable powder formulations (16).
TOXICOLOGICAL EFFECTS
ACUTE TOXICITY
Fluometuron is moderately toxic to humans by ingestion and slightly toxic by dermal
absorption (18). The major routes of exposure to this herbicide
are from inhalation and absorption through the skin (13). It
may be fatal if inhaled, swallowed, or absorbed through skin, as it is irritating
to the mucous membrane lining the skin, gastrointestinal tract, and respiratory
system (2). While there have been no reports of cases of fluometuron
poisoning in humans, this herbicide is considered a mild inhibitor of cholinesterase.
Cholinesterase is an essential enzyme of the nervous system. Cholinesterase inhibition
was observed in guinea pigs exposed by inhalation to 588 mg/m3 for 2 hours (18).
(For more information, refer to the Toxicology Information Brief on Cholinesterase-Inhibition).
Fluometuron caused an increased white blood cell count in agricultural workers
(3).
Symptoms of fluometuron poisoning in rats include muscular weakness, tearing
or watery eyes, extreme exhaustion and collapse (15).
Fluometuron is a mild skin and eye irritant. It has caused skin sensitization
in guinea pigs and in humans (18). It affects the cornea of
the eye in such a way that light cannot pass through it. This condition is referred
to as corneal opacity (1, 13, 15).
Skin or eye contact with it may cause burning (11).
The amount of a chemical that is deadly when given by mouth to one- half (50%)
of test animals, is referred to as its acute oral lethal dose fifty, or LD50.
The acute oral LD50 for fluometuron in rats is 1,515 to 8,900 mg/kg, and in
rabbits is 2,500 mg/kg. In mice and guinea pigs, it has an LD50 of about 800
to 900 mg/kg of body weight. In rabbits, its dermal LD50 is approximately 3,000
- 10,000 mg/kg (3, 15, 16,
18).
CHRONIC TOXICITY
Rats were fed 7.5, 75, or 750 mg/kg/day for 90 days. At the 750 mg/kg dose, decreased
body weight and congestion in the spleen, adrenals, liver, and kidneys were evident.
The NOAEL for this study was 7.5 mg/kg/day (100 ppm). 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 150 mg/kg dose. No effects were seen at 15 mg/kg/day
(400 ppm) (20).
Prolonged or repeated exposure to fluometuron may cause conjunctivitis (18).
The EPA has established a Lifetime Health Advisory (LHA) level of 90 micrograms
per liter (ug/l) for fluometuron in drinking water. This means that EPA believes
that water containing fluometuron at or below this level is acceptable for drinking
every day over the course of one's lifetime, and does not pose any health concerns.
However, consumption of fluometuron at high levels well above the LHA level
over a long period of time has been shown to cause damage to the liver, kidneys
and spleen in animals studies (19).
Reproductive Effects
There is a data gap in the information on the reproductive effects of fluometuron
(13).
Teratogenic Effects
Pregnant rabbits were given doses of 50, 500 or 1,000 mg/kg/day by gavage 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 1,000 mg/kg/day (20).
Mutagenic Effects
In two separate assays, one on yeast and the other on bacterial cell cultures,
fluometuron failed to cause mutations. Fluometuron interfered with DNA synthesis
in the testes of mice given a single oral dose of 2,000 mg/kg (20).
Carcinogenic Effects
EPA has determined that there is not enough evidence that fluometuron causes cancer
in animals to justify its classification as a carcinogen. Fluometuron is not classified
as a carcinogen by the EPA (20). An increased incidence of liver-cell
tumors in male mice was noted in a study of rats and mice. In the same study,
no carcinogenic effects were observed in female mice or in rats of either sex
(18). Mice that were given oral doses of 87 mg/kg for two years
had evidence of liver tumors and leukemia, a condition characterized by uncontrolled
growth in the number of white blood cells in the blood stream (7).
Organ Toxicity
Toxic injury to the liver, kidneys, gut and brain is induced when lethal doses
of fluometuron are administered experimentally (10). An increase
in spleen weight and in the incidence of abnormalities in red-blood cells, and
decreased weight gain in females were observed in a 90-day study of rats (18).
Fate in Humans and Animals
Fluometuron is absorbed only slowly into the body from the gastrointestinal tract.
72 hours after rats were given oral doses of 50 mg/kg radio-labeled fluometuron,
15% of the dose was excreted in the urine and 49% in the feces. At the same time,
radioactivity was detected in the rats' livers, kidneys, adrenal glands, pituitary
glands, red blood cells, blood plasma and spleens, with the highest concentration
found in red blood cells (20).
Excretion in the feces indicates that the compound remained in the gastrointestinal
tract and was not absorbed into the bloodstream. Since fluometuron is stored
only briefly in body tissues, a substantial amount of the herbicide is excreted
intact (10).
ECOLOGICAL EFFECTS
Effects on Birds
The EPA characterizes fluometuron as ranging from being slightly toxic to practically
nontoxic to birds (13). Eighty percent wettable powder fluometuron
had an oral LD50 of more than 2,000 mg/kg in three- to four-month old female mallards.
Signs of herbicide poisoning in these ducks included imbalance, falling, fluffed
feathers, and hyperexcitability. These signs showed up in the ducks within 15
minutes of treatment and persisted for up to a week (5).
The lethal concentration fifty, or LC50, is concentration of a chemical in
water or air which causes death in 50% of an experimental animal population
after exposure for a specified length of time. The 8- day dietary LC50 in ppm
for technical fluometuron is 4,620 for Japanese quail, 4,500 for mallard ducks,
and 3,150 for ring-neck pheasants (15).
Effects on Aquatic Organisms
Fluometuron is slightly toxic to fish. The 96-hour LC50 of technical fluometuron
is 47 ppm in rainbow trout, 96 ppm in bluegill sunfish, and 55 ppm in catfish
(15).
Effects on Other Animals (Nontarget species)
Fluometuron is relatively nontoxic to wildlife and bees (15).
ENVIRONMENTAL FATE
Breakdown of Chemical in Soil and Groundwater
The capacity for fluometuron to move through the ground varies with the soil type
to which it is applied. It was very mobile in both sandy and silt loam soils (20).
Its mobility and herbicidal activity both decrease as the organic matter content
of the soil increases (10). Fluometuron is readily soluble in
water (110 ug/ml) (17). While the relatively easy movement of
this herbicide through the soil improves its capacity to control weeds that germinate
deep in soil, such mobility, or leaching, increases its potential to contaminate
groundwater (15). Fluometuron has been placed on the EPA list
of possible groundwater contaminants (13). Although it was not
found in groundwater during a national survey, the EPA considers fluometuron to
be one of the pesticide compounds with the greatest potential for leaching into
groundwater (14).
Degradation of fluometuron by soil microbes may be very rapid. Some field and
lab soil dissipation studies show a half-life of approximately 30 days, while
others indicate that this period is less than 24 weeks (14).
Residues of fluometuron have dissipated to levels that were not detectable (less
than 0.10 ppm) within four months of the last application at normal usage rates
(15). A European study indicated that in sandy clay loams,
fluometuron dissipates with a half-life of less than 340 days (13).
A soil half-life as short as 11 days has been reported (17).
Field studies show that runoff from soil into surface waters is insignificant,
with an average loss of less than 1% of the total fluometuron applied (15).
Photodecomposition is not expected to occur in the field because of application
methods. Volatilization is not a significant route of dissipation of fluometuron
in the field (15).
Breakdown of Chemical in Water
Fluometuron products should not be applied to water or wetlands, and cleaning
of equipment or disposal of waste related to this herbicide can contaminate water
(13). The half-life of fluometuron in water (hydrolysis half-life)
is 110 to 144 weeks (14). At 20 degrees C, half- life values
of fluometuron aqueous solutions with pH 5 to 9, are between 730 and 1,010 days.
It is stable at pH values ranging from one to 13, at this temperature (15).
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.
Breakdown of Chemical in Vegetation
Fluometuron is more readily absorbed by roots from soil application, than by leaves
from foliar application. The addition of a surfactant or nonphytotoxic oil to
spray solutions improves the absorption of fluometuron by leaves. Fluometuron
has been shown to undergo a 3-step degradation process in plants. The rate at
which it is absorbed, translocated, and subsequently broken down, or metabolized,
differs with various plant species. An understanding of these differences is important
in determining the tolerance or susceptibility of plants and weeds to this chemical
(15). Cotton exhibits a remarkable ability to breakdown fluometuron
(10). All fluometuron product labels warn against the crop injury
which may result if any crops other than sugarcane or cotton are planted within
a one-year period after the last application of this material (13).
The following crop plants may have special sensitivities to fluometuron: sugarbeets,
red beets, cole crops, cucurbits, and eggplant (15).
PHYSICAL PROPERTIES AND GUIDELINES
Fluometuron is a white to tan powder or crystalline material with an amine-like
odor. It is nonflammable and noncorrosive (15, 18).
It is compatible with other herbicides (10). While it is stable
at room temperature, fluometuron is broken down (hydrolyzed) by acids or bases
at elevated temperatures (13, 18). It poses
a fire and explosion hazard in the presence of strong oxidizers. Fluometuron is
stable under normal temperatures and pressures, but it may pose a slight fire
hazard if exposed to heat or flame and containers may explode in the heat of a
fire. Thermal decomposition may release highly toxic fumes of fluorides and oxides
of nitrogen and carbon (18). Runoff from fire control water
may also give off poisonous gases and cause pollution (11).
Fluometuron should be kept out of the reach of children and domestic animals.
It may be harmful if swallowed. Breathing of, and eye contact with, fluometuron
dust should be avoided. Dust may be irritating to the lungs and eyes (15).
Mixers, loaders and applicators must wear protective clothing when handling
this product. Protective clothing includes coveralls, long-sleeved shirt, shoes,
impermeable gloves, and eye protection (13).
Formulations of fluometuron intended for cotton use should not be applied within
six days of cotton harvest. Foliage from fluometuron- treated cotton plants
must not be fed to livestock. Sugarcane formulations should not be applied within
180 days of harvest, and livestock must not be grazed in treated fields (13).
Occupational Exposure Limits:
No occupational exposure limits have been established for fluometuron by OSHA,
NIOSH, or ACGIH (18).
Physical Properties:
CAS #: |
2164-17-2 |
Specific gravity: |
1.39 (18) |
H20 solubility: |
90 ppm (14) 0.0105 % at 20 degrees C (18) |
Solubility in other solvents: |
at 20 degrees C, acetone, 15%; chloroform, 2%; methanol, 14%;
hexane <4%(13). Fluometuron is readily soluble in organic
solvents (16). Slightly soluble in hexane (18). |
Melting Point: |
163-164 degrees C (325-329 degrees C) (15) |
Vapor pressure: |
5 x 10 to the minus 7 power mm Hg at 20 degrees C (15) |
Kow: |
log Kow: 1.34 (9) |
Koc: |
175; 370 (calc) (14) |
Kd: |
Class 3, Intermediate (14); (PC - partition
coefficient): 174 (8) |
Chemical Class/Use: |
Substituted urea herbicide |
NOEL: |
7.5 mg/kg for rats; 400 ppm for dogs (13) |
BASIC MANUFACTURER
Ciba-Geigy Corporation
Agricultural Division
PO Box 18300
Greensboro, NC 27419
Review by Basic Manufacturer:
Comments solicited: November, 1992
Comments received: April, 1992
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Publishing Company.
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Second edition. U. S. Department of the Interior. Fish and Wildlife Service.
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Sciences, University of Florida. Soil Science fact sheet adapted from: Herbicide
injury, symptoms and diagnosis, Skroch and Sheet, eds. 1981 (Dec.). North
Carolina Agricultural Extension Service. AG-85.
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Guidebook for hazardous material incidents. G-31. Washington, DC.
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Office of Public Affairs (A-107). Washington, DC.
- _____. 1985 (Dec). Chemical fact sheet for fluometuron. Fact sheet no. 88.
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contaminants. Office of Pesticides and Toxic Substances. Washington, DC. Photocopy.
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SCS/ARS/CES Pesticide Properties Database: Version 2.0 (Summary). USDA - Soil
Conservation Service, Syracuse, NY.
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OHS Inc., Secaucus, NJ.
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