chlorimuron ethyl (DPX F6025) Herbicide Profile 4/86
CHEMICAL FACT SHEET FOR:
FACT SHEET NUMBER: 82
DATE ISSUED: APRIL 4, 1986
1. DESCRIPTION OF CHEMICAL
Generic Name: ethyl 2-[[[[(4-chloro-6-methoxypyrimidin-2-yl)
- 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. duPont de Nemours & Company
2. USE PATTERNS AND FORMULATIONS
- Application sites: soybeans
- Types and methods of application: Postemergence foliar by ground
- Application rates: 1/2 to 3/4 oz. a.i./A
- Types of formulations: 25% dispersible granule
- Usual carrier: water
3. SCIENCE FINDINGS
- Physical state: solid
- Color: off-white to pale yellow
- Odor: none
- Melting point: 181 degrees C
- Density: 1.51 gram/cc
- Solubility in various organic solvents at 25 degrees 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; xylene, 0.283
- Solubility in water at controlled pH:
7 0 1200
- Handling characteristics: Store product in original container
- Acute toxicity:
- Acute oral toxicity (rat): > 5,000 mg/kg, Toxicity Category IV
- Acute dermal toxicity (rabbits): > 2,000 mg/kg,
Toxicity Category III
- Primary eye irritation (rabbit): Draize score = 1,
Toxicity Category III
- Primary dermal irritation (rabbit): Primary irritation score from
0.13 to 0.63, Toxicity Category IV
- Primary skin irritation (guinea pig): Not irritating,
Toxicity Category IV
- Dermal sensitization (guinea pig): Not a sensitizer,
Toxicity Category IV
- 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.
- 1-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).
- 2-generation reproduction study (rat): Resulted in a maternal
toxicity NOEL of 12.5 mg/kg/day and a fetotoxic NOEL of 1.25
- Teratology study (rat): Resulted in a teratogenic NOEL of 150
mg/kg/day, a maternal toxicity NOEL of 30 mg/kg/day, and a fetotoxic
NOEL of 30 mg/kg/day.
- Teratology study (rabbit): 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
- Metabolism in plants: Tolerant species metabolize the compound to
- Persistence in plants: Does not persist in plants.
- 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 loams. 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.
- 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
- Bioaccumulation: The octanol/water partition coefficient (Kow) of 1.3
and available information show the hydrolysis products have a lower
Kow. 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 persistence: Chlorimuron ethyl has a half-life of
7.5 weeks in soil.
- Environmental fate and surface and groundwater contamination concerns:
Chlorimuron methyl has the potential to leach and contaminate
groundwater 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.
- Avian acute toxicity (mallard duck): > 2,510 mg/kg
- Avian dietary toxicity (bobwhite quail): > 5.620 ppm
- Avian dietary toxicity (mallard duck): > 5,620 ppm
- 96-hour 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
- 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.
- 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-[[[[(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 100-fold safety factor is
calculated to be 0.0625 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 0.000690 mg/day/ 1.5 kg. The current
action will use 0.0184% of the ADI. There are no other published
tolerances for this chemical.
Summary Science Statement
- All data required for registration of this chemical are acceptable to
- 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
- The pesticide will leach in some soils and has the potential to
contaminate groundwater at very low concentrations. Chlorimuron 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 ppm on soybeans.
4. SUMMARY OF REGULATORY POSITION AND RATIONALE
- The Agency has registered chlorimuron ethyl for postemergence use
- 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
6. CONTACT PERSON AT EPA
Robert U. Taylor
Office of Pesticide Programs
Registration Division (TS-767C)
401 M Street S.W.
Washington, DC 20460
DISCLAIMER: THE INFORMATION PRESENTED IN THIS CHEMICAL INFORMATION FACT
SHEET IS FOR INFORMATIONAL PURPOSES ONLY AND NOT TO BE USED TO FULFILL
DATA REQUIREMENTS FOR PESTICIDE REGISTRATION AND REREGISTRATION.