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n. OC 20460
xvEPA Pesticide
Fact Sheet
Name of Chemical: Chlorimuron ethyl
Reason for Issuance: New Chemical Registration
Date Issued: « • 4
Fact Sheet Number: 82
1. Description of Chemical
Generic Name: Ethyl 2-[[[((4-chloro-6-methoxyprimidin-
2-yl)amino]carbonyl]amino]sulfonyl]benzoate
Common Name: Chlorimuron ethyl; DPX-F6025
Trade Name: DuPont Classic Herbicide
EPA Shaughnessy Code: 128901
Chemical Abstracts Service (CAS) Number: 90982-32-4
Year of Initial Registration: 1986
Pesticide Type: Herbicide
Chemical Family: Sulfenylurea
U.S. and Foreign Producers: E.I. du Pont de Nemours
& Company
2. Use Patterns and Formulations -
Application sites: Soybeans
Types and methods of application: Postemergence foliar
by ground equipment.
Application rates: 1/2 to 3/4 ounces active ingredient
per acre (oz ai/A)
Types of formulation: 25% dispersible granule
Usual carrier: water
3. Science Findings
Summary Science Statement:
All data required for registration of this chemical
is acceptable to the Agency.
Chlorimuron ethyl has low acute toxicity (Category
III) for acute dermal and primary eye irritation and
Category IV for all other forms of acute toxicity.
It was not oncogenic to mice or rats, not teratogenic
to rabbits, and not mutagenic. 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.
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The pesticide will leach in some soils and has the
potential to contaminate ground water at very low
concentrations. Chiorimuron ethyl is practically
nontoxic to birds and slightly toxic to. fish and
invertebrates. The nature of residues in plants is
adequately understood and adequate methodology is
available for enforcement of a tolerance of 0.05
part per million (ppm) 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/l00 ml
Acetone 7.05
Acetonitrile 3.10
Benzene 0.815
Ethyl acetate 2.36
Ethyl alcohol 0.392
rt—hexane 0.006
Methyl alcohol 0.740
Methylene chloride 15.3
Xylenes 0.283
Solubility in water at controlled pH:
Solubility milligram/liter (ing/l )
1.3 1.5
1.9 1.5
2.5 1.5
4.2 4.1
5.0 9.0
5.8 99
6.5 450
7.0 1200
Handling characteristics: Store product in original
container only.
Toxicology Characteristics:
Acute Toxicity:
Acute Oral Toxicity (Rat): Greater than C>) 5000 milligrams/
kilogram (mg/kg)
Toxicity Category IV ’ !
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Acute Dermal Toxicity (Rabbits): > 2000 mg/kg
Toxicity Category 1111/
Primary Eye Irritation (Rabbit): Draize score = 1
Toxicity Category 1111/
Primary Dermal Irritation (Rabbit: ) Primary irritation
score from .13 to .63
Toxicity Category 1V 1 /
Primary Skin Irritation (Guinea Pig): Not irritating
Toxicity Category IV ’ !
Dermal Sensitization (Guinea Pig): Not a sensitizer
Toxicity Category 1V 1 /
1/ Labeling statements reauired for: Toxicity Category
III for acute dermal — “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
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 (HDT).
Chronic Feeding/Oncogenic Study (Rat) resulted in a NOEL
of 12.5 mg/kg/day and no oncogenic effects at 125 mg/kg/
day (HDT).
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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 (Rats) resulted in a teratogenic NOEL
of 150 mg/kg/day, a maternal toxicity NOEL of 30 nig/
kg/day and a fetotoxic NOEL of 30 mg/kg/day.
Teratology Study (Rabbits) resulted in a maternal toxicity
of 60 mg/kg/day and a fetotoxic NOEL of 15 mg/kg/day
and no teratogenic effects at 300 mg/kg/day (HDT).
Mutagenicity (in vivo bone marrow test) — not mutagenic.
Mutagenicity (Ames test) — not mutagenic.
Mutagenicity (Unscheduled DNA Synthesis Activity) —
not mutagenic.
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 compound to nonherbicidal metabolites.
Persistance in plants: Does not persist in plants.
Environmental Characteristics:
Adsorption and leaching in basic soil types. Chlorimuron
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 the silt loazns. DPX—F6025 had low
mobility on Keyport silt loam, intermediate mobility
on Flanagan silt loam and Cecil sandy loam and high
mobility on Woodstown sandy loam.
Microbial breakdown: Initial deactivation of the molecule
is through hydrolysis followed by complete metabolism
to low molecular weight compounds through normal soil
microbial degradation.
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Loss from photodecomposition and/or volatilization:
Photodegradation of chlorimuron ethyl is not a major
degradation pathway, but did proceed at twice the
-rate in exposed samples compared to the nonexposed
sampl es.
Bioaccumulation: The octanol/water partition coefficient
(Kow) of 1.3 and available information show the
hydrolysis products have a lower K 0 w. Since the
correlation between octanol/water partitioning and
fish accumulation is only accurate within a factor
of 100, chlorimuron ethyl and its degradation products
have potential to accumulate in fish to levels 130
times higher than levels in water.
Resultant average persistance: Chiorimuron ethyl has a
half—life of 7.5 weeks in soil.
Environmental fate and surface and ground water
contamination concerns: Chiorimuron methyl has the
potential to leach and contaminate ground water at
very low concentrations.
Exposure of humans and nontarget organisms to pesticide
or degradates. Human risk from exposure is minimal
because of low acute toxicity (Category III and IV).
Nontarget organism risk from exposure is minimal
because maximum expected residues on soil and water
do not approach the toxicity values for the organisms
tested.
Ecological Characteristics:
Avian Acute Toxicity (Mallard duck): > 2510 mg/kg
Avian Dietary Toxicity (Bobwhite quail): > 5620 ppm
Avian Dietary Toxicity (Mallard duck): > 5620 ppm
96—Hour Fish Toxicity (Rainbow trout): > 12 mg/i
96—Hour Fish Toxicity (Bluegill sunfish): > 10 mg/i
48—Hour Invertebrate Toxicity ( Daphnia magna) : > 10 mg/i
Chlorimuron ethyl is practically nontoxic 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 low toxicity and low
application rate.
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
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[ HPLC] using a photoconductivity detector) is available
for enforcement.
Tolerances are established for residues of the
herbicide chlorimuron ethyl (ethyl 2— [ [ [ [ (4—chloro—6—
methoxypyrimidin—2—yl )amino] carbonyl] amino) sulfonyl]
benzoate in or on soybeans at 0.05 ppm.
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/kg/day.
The theoretical maximum residue contribution (TMRC) for
this tolerance for a 1.5 kg diet is calculated to be
.000690 mg/day/1.5 kg. The current action will use
.0184 percent of the ADI. There are no other published
tolerances for this chemical.
4. Summary of Regulatory Position and Rationale
Position: The Agency has registered chiorimuron
ethyl for postemergence use on soybeans.
Rationale: All data required for registration have
been submitted. All submitted data
fulfill guideline requirements and are
acceptable to support registration.
5. Summary of Major Data Gaps
None
6. Contact Person at EPA
Robert J. Taylor
Environmental Protection Agency
Office of Pesticide Programs
Registration Division (TS—767C)
401 M Street, SW.
Washington, DC 20460
Phone: (703) 557—1800
Disclaimer : The information presented in this Pesticide Fact
Sheet is for informational purposes only, and may
not be used to fulfill data requirements for pesticide
registration and reregistration.
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