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chlorimuron ethyl (DPX F6025) Herbicide Profile 4/86

                            CHEMICAL FACT SHEET FOR:
                               CHLORIMURON ETHYL
                        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
Chemical Characteristics
- 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:
            pH               mg/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.		~.
Toxicological Characteristics
- 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
    mg/kg/day.	~_~
  - 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
    acid synthesis.
  - Metabolism in plants: Tolerant species metabolize the compound to
    non-herbicidal metabolites.
  - Persistence 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 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
  non-exposed samples.
- 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.
Ecological Characteristics
- 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.
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-[[[[(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
  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
- 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.
- The Agency has registered chlorimuron ethyl for postemergence use
  on soybeans.
- 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
Telephone:  703/557-1800