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Pesticide
Fact Sheet
Name of Chemical. Qiioriinuron Ethyl (Classic)
Reason for Issuance: New Chanical Reg.
Date Issued: July 30, 1987
Fact Sheet Number: r? i
Description of Chemical
Generic Name: Ethyl 2-[[[[(^-chloro-6-raethoxyprlmldln-
2-yl)amlno]carbonyl]amino]sulfonyl]benzoate
Common Name: Chlorlmuron ethyl
Trade Name: DuPont Classic Herbicide; DPX-F6025
EPA Shaughnessy Code: 128901
Chemical Abstracts Service (CAS) Number: 90982-32-^
Year of Initial Registration: 1986
Pesticide Type: Herbicide
Chemical Family: Sulfonylurea
U.S. and Foreign Producers: E.I. du Pont de Nemours
& Company
Use Patterns and Formulations
Application Site: Soybeans
Types and Methods of Application: Postemergence and preemergen
foliar by ground equipment.
Application Rates: 1/2 to 1 1/2 ounces active ingredient
per acre (oz al/A) preemergence.
1/8 to 3/l6 (oz al/A) postemergence.
Types of Formulation: 25% dlsperslble granule
Usual Carrier: Water
Science Findings
Summary Science Statement:
All data required for registration of this chemical
are acceptable to the Agency.
Chlorlmuron ethyl has low acute toxicity (Category
III for acute dermal and primary eye Irritation and
Category IV for all other forms of acute toxicity.)
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It was not oncogenic to mice or rats, not teratogenic
to rabbits or rats, and not nutagenic. The pesticide
is foliarly absorbed and translocated within the plant.
It works by inhibition of cell division in shoots and
roots. The major degradation pathway is hydrolysis.
The pesticide will leach in sane soils and has the to
potential contaminate ground water at very lew concent-
rations. Chlorinuron ethyl demonstrates negligible
toxicity nontoxic to birds and slightly toxic to fish
and invertebrates. The nature of residues in plants
is adequately understood and adequate metlxxiology is
available for enforcement of a tolerance of 0.05 part
per million (pptn) on soybeans.
Chemical Characteristics:
Physical State: Solid
Color: Off-white to pale yellow
Odor: None
Melting Point: 181 °C
Density: 1.51 gram/cubic centimeter (g/cc)
Solubility in various organic solvents at 25 °C
g/100 mL
Acetone
7.05
Acetonitrile
3.10
Benzene
0.815
Ethyl acetate
2.36
Ethyl alcohol
0.392
n-hexane
0.006
Methyl alcohol
0.740
Methylene chloride
15.3
Xylenes
0.283
Solubility in Water at Controlled pH:
pH Solubility grams/lOOcc
1.3 .015
1.9 .015
2.5 .015
4.2 .041
5.0 .090
5.8 .990
6.5 4.500
7.0 12.000
Handling Characteristics: Store product in original container only.
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Toxicology Characteristics:
Acute Toxicity:
Acute Oral Toxicity (Rat): Greater than (>) 5000 milligrams/
kilogram (mg/kg)
Toxicity Category IVV
Acute Dermal Toxicity (Rabbits): > 2000 mg/kg
Toxicity Category IIlV
Primary Eye Irritation (Rabbit): Draize score = 1
Toxicity Category IIIV
Prinary Dental Irritation (Rabbit): Primary irritation
score from .13 to .63 Toxicity Category IvV
Primary Skin Irritation (Guinea Pig): Not irritating
Toxicity Category IvV
Dental Sensitization (Guinea Pig): Not a sensitizer
Toxicity Category IvV
V Labeling statements required for: Toxicity Category
III for acute dental - "Harmful if absorbed
through skin. Avoid contact with skin, eyes,
or clothing. Wash thoroughly with soap and
water after handling."
Toxicity Category III for primary eye irritation -
"Causes (moderate) eye injury (irritation). Avoid
contact with eyes or clothing. Wash thoroughly
with soap and water after handling."
Toxicity Category IV - no precautionary statements
required.
Major Routes of Exposure:
The major routes of exposure are via dermal and eye contact.
Chronic Toxicity:
90-Day Feeding Study (Mouse) resulted in a no observable-effect
level (NOEL) of 18.75 mg/kg/day.
90-Day Feeding Study (Dog) resulted in a NOEL of
2.5 mg/kg/day.
One-Year Feeding Study (Dog) resulted in a NOEL of
6.25 mg/kg/day.
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18-Month Chronic Feeding/Oncogenicity Study (Mouse) resulted in
a NOEL of 3.75 mg/kg/day and no oncogenic effects at 187.5
mg/kg/day for the highest dose tested (HOT).
Chronic Feeding/Onoogenic Study (Rat) resulted in a NOEL of 12.5
mg/kg/day and no oncogenic effects at 125 mg/kg/day (HOT).
2-Generation Reproduction Study (Rat) resulted in a maternal
toxicity NOEL of 12.5 mg/kg/day and a fetotoxic NOEL of 1.25
mg/kg/day.
Teratology Study (Rat) resulted in a maternal toxicity NOEL of
30 mg/kg/day, and a developmental toxicity NOEL of 30 mg/kg/day.
Teratology Study (Rabbit) resulted in a maternal toxicity of 60
mg/kg/day and a developmental toxicity NOEL of 15 mg/kg/day.
Mutagenicity (in vivo Bone Marrow Test) - not mutagenic.
Mutagenicity (Ames test) - not mutagenic.
Mutagenicity (Unscheduled DNA Synethsis Activity) - not nutagenic.
Physiological or Biochemical Behavioral Characteristics:
Foliar absorption: Rapid.
Translocation: Systemic after absorption through either the
foliage or the roots.
Mechanism of pesticidal action: Inhibits plant cell division of
rapidly growing tips of roots and shoots by inhibition of
amino acid synthesis.
Metabolism in plants: Tolerant species metabolize the corrpound
to noriherbicidal metabolites.
Persistence in plants: Does not persist in plants.
Environmental Characteristics:
Adsorption and leaching in basic soil types: Chlorifturon ethyl
was very weakly absorbed on the two sandy loam soils and only
weakly absorbed on the two silt loam soils. Absorbed radioactivity
was readily desorbed from the sandy loam soils, but was more
tightly retained on silt loams. Chloroinuron ethyl had low
mobility on Keyport silt loam, intermediate mobility on Flanagan
silt loam and Cecil sandy loam, and high mobility on Woods town
sandy loam.
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Microbial breakdown: Initial deactivation of the molecule is through
hydrolysis followed by conplete metabolism to low molecular
weight compounds through normal soil microbial degradation.
Loss from photodeoonposition/volatilization:
Fhotodegradation of chlorinuron ethyl is not a major degradation
pathway, but did proceed at twice the rate in exposed sanples
oonpared to the nonexposed sanples.
B ioaccumulation:
The octanol/water partition coefficient (Kq^) of 1.3 and
available information show the hydrolysis products have a
lower Kq^. Since the correlation between octanol/water partitioning
and fish accumulation is only accurate within a factor of 100,
chlorinuron ethyl and its degradation products have potential
to accumulate in fish to levels 130 times higher than levels
in water.
Resultant average persistence:
Chlorinuron ethyl has a half-life of 7.5 weeks in soil.
Environmental fate and surface and ground water contamination
concerns:
Chlorinuron methyl has the potential to leach and contaminate
ground water at very low concentrations.
Exposure of humans and nontarget organisms to pesticide or
degradates:
Hunan risk frcm exposure is minimal because of lew acute
toxicity (Category III and IV). Nontarget organism risk from
exposure is minimal because maxinum expected residues on soil
and water do not approach the toxicity values for the organisms
tested.
Ecological Characteristics:
Avian Acute Toxicity (Mallard Dude): > 2510 mg/kg
Avian Dietary Toxicity (Bofcwhite (Xiail): > 5620 ppm
Avian Dietary Toxicity (Mallard Duck): > 5620 ppm
96-Hcur Fish Toxicity (Rainbow Trout): > 12 mg/L
96-Hour Fish Toxicity (Bluegill Sunfish): > 10 mg/L
48-Hour Invertebrate Toxicity (Daphnia magna) > 10 mg/L
48-Hour Acute Toxicity (Honey Bees): 12.5 ug/bee
Chlorinuron ethyl demonstrates negligible toxicity to birds on
both an acute and dietary basis. It is slightly toxic to fish
and invertebrates. It is not expected to adversely affect
endangered/threatened species because of lew toxicity and lew
application rate.
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Tolerance Assessment:
The nature of the residue In plants is adequately
understood. The residue of concern is chlorimuron ethyl.
Adequate methodology (high pressure liquid chromatography
[HPLC] using a photoconductivity detector) is available for
enforcement.
Tolerances are established for residues of the herbicide
chlorimuron ethyl (ethyl 2-[[[[(1<-chloro-6-methoxypyrimidin-2-
yl)amino]carbonyl]amino]sulfonyl] benzoate in or on soybeans
at 0.05 ppn.
The acceptable daily intake (ADI) based on the 1-year dog
feeding study (NOEL of 6.25 mg/kg/day) and using a hundredfold
safety factor is calculated to be .0625 mg/kg/day. The maximum
permissible Intake (MPI) for a 60 kg human is calculated to be
3.70 mg/day. The theoretical maximum residue contribution
(TMRC) for this tolerance for a 1.5 kg diet is calculated to
be .000012 mg/day. The current action will use .018^4 percent
of the ADI. There are no other published tolerances for this
chemical.
4. Sunmary of Regulatory Position and Rationale
a. None of the risk criteria listed In 40 CFR 15*1.7 have been exceeded
for chlorimuron ethyl. TVie Agency will issue registrations for
substantially similar products and will issue significant new uses.
Rationale: A review of available data Indicate that no risk criteria
have been exceeded or met for chlorimuron ethyl.
b. The Agency is not imposing a ground water advisory statement for
chlorimuron ethyl.
Rationale: Even though chlorimuron ethyl has the potential to
leach in some soils and contaminate ground water at very low levels,
the available data do not indicate a concern for ground water
contamination. This was determined by consideration of the low
application rates (ounces per acre) and the very low levels expected
to reach ground water.
.>
c. The Agency Is not requiring reentry data or protective clothing
for chlorimuron ethyl.
Rationale: Human risk from exposure is minimal because of the low
acute toxicity.
d. The Agency is not imposing endangered species labeling for the use
on soybeans.
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Rationale; Based on the low toxicity and low application rate,
chlorimuron ethyl is not expected to adversely affect endangered
animal species. Refer to sections on ecological characteristics
and endangered species in Chapter III for detailed information on
available data.
e. Additional residue data are not required to support the use on
soybeans.
Rationale: The Agency has determined that available residue data
adequately support the established tolerance on soybeans.
P. Additional data are being required on droplet size spectrum,
drift field evaluation, seed germination/seedling emergence,
vegetative vigor, and aquatic plant growth.
Rationale: The agency has determined that the potential
for off target movement and carryover of this chemical are not
adequately understood. This lack of definition, coupled with
the low volume application of this herbicide, make these studies
necessary.
5. Sunmary of Major Data Gaps
None.
6. Contact Person at EPA
Robert J. Taylor
Product Manager 25
Registration Division (TS-767C)
Office of Pesticide Programs
Environmental Protection Agency
401 M Street SW.
Washington, DC 20460
Telephone: (703) 557-1800
Disclaimer: The Information presented in this Pesticide Pact
Sheet is for Informational purposes only, and may
not be used to fulfill data requirements for pesticide
registration and reregistratlon.
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