United States Office of Pesticides and Toxic Substances
Environmental Protection Office of Pesticide Programs (TS-766C)
Agency Washington, DC 20460
4»EPA Pesticide
:act Sheet
Name of Chemical: ASSERT
Reason for Issuance: New Chemical Registration
Date Issued: April 1988
Fact Sheet Number: 159
1. Description of Chemical
Chemical Name: A mixture of methyl-2-(4-isopropyl-4-methyl-5-oxo-2-
imidazolin-2-yl)-p-to1uate and methyl-6-(4-isopropyl-4-
methyl-5-0X0-2-imidazolin-2-yl)-m-toluate
CAS Number:
Trade Name: ASSERT Herbicide
EPA Shaughnessy Codes: 128842 and 128843
Year of Initial Registration: 1988
Pesticide Type: Herbicide
U.S. and Foreign Producers: American Cyanamid Company
2. Use Patterns and Formulations
Application Sites: Sunflowers, Wheat and Barley
Types and Formulations: Liquid Concentrate
Types and Methods of Application: The product is applied as a
postemergence spray by air or
ground equipment.
Applicate Rates: 0.18 to 0.46 Ib ai/acre.
Usual Carrier: Water
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3. Science Findings :
Summary Science Statement: All data required for registration of
this chemical are acceptable to the Agency. However, an additional
field dissipation study is being required due to leaching potential.
The current data base does not suggest any major toxicological problems.
Acute toxicology data on the technical grade active ingredient indicate
that the chemical is extremely caustic and corrosive. The toxicology
category is I (Danger), based on primary eye and skin irritation
studi es.
Chemical Characteristics :
Physical State: Solid
Color: Off white to pale yellow
Odor: Musty odor
Melting Point:
113 °C - 153 °C (Range due to Isomer ratio and
effects of impurities)
g/rnl at 20 °C
875 ppm water; p-isomer 875 ppm In water at 25 °C;
rn—isomer 1370 ppm in water at 25 °C
Dissociation Constant (Pka) 2.9 at 23.5 °C
Octanol/Water Partition Coefficient: p—isomer 35
rn-isomer 66
Stability: Technical material was stable for 2 years at
ambient temperature.
Toxicology Characteristics :
Acute Toxicity: (End—use products)
Density: 0.3
Solubil ity:
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Acute Oral Toxicity (Rat): Greater than (>) 5000 miiiigrams/
kilogram (mg/kg) ,Toxicity Category
Iv 1/
Acute Dermal Toxicity (Rabbit): Greater than 2000 mg/kg,
Toxicity Category III 1/
Primary Eye Irritation (Rabbit): Toxicity Category III 1/
Primary Dermal Irritation (Rabbit): Toxicity Category III 1/
Acute Inhalation Toxicity (Rat): Greater than 518 mg/i
Toxicity Category IV 1/
Dermal Sensitization (Guinea Pig): Not a sensitizer
Major Routes of Exposure: The major routes of expsoure are via
dermai and eye contact.
Chronic Toxicity: 90-Day Feeding Study (Rat) resulted in a no-
observable-effect level (NOEL) of 1000 ppm.
1/ Labeling statements required 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.
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Major Routes of Exposures :
The Major routes of exposures are via dermal and eye contact.
Chronic Toxicity :
90-Day Feeding Study (rat) resulted in a (NOEL) of 1000 ppm.
One-year Feeding Study (dog) resulted in a NOEL of 1.25 mg/kg/day.
18-month Chronic Feeding/Oncogenicity Study (mice) resulted in a
NOEL of 750 mg/kg/day and no oncogenic effects at 750 mg/kg/day
for the hightest dose tested (HDT).
3—Generation Reproduction Study (rat) resulted in a maternal
toxicity NOEL of 25 mg/kg/day, and a fetotoxic NOEL of 250 mg/kg/day.
Teratology Study (rat) resulted In a maternal toxicity
NOEL of less than 250 mg/kg/day and a developmental toxicity
LEL (lowest effect level) of 500 mg/kg/day.
Teratology Study (rabbit) resulted in a maternal toxicity of 750
mg/kg/day, and a developmental toxicity NOEL of 250 mg/kg/day.
Mutagenicity (in vivo bone marrow test) - Not mutagenic.
Mutagenicity (Ames test) - Not mutagenic.
Mutagenicity (unscheduled DNA synethsls activity) - Not mutagenic.
Physiological or Biochemical Behavioral Characteristics :
Foliar absorption: Rapid.
Translocation: Systemic after absorption through either the
roots or foliage.
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.
Environmental Characteri stics :
Absorption in basic soils types: Assert was very weakly absorbed on the
two sandy loam soils and on the two silt loam soils.
Environmental fate and surface and ground water contamination
concerns: Assert has the potential to leach and contaminate groundwater
at very low concentrations. Therefore, the Agency is requesting
additional field dissipation studies.
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Resultant Average Persistence: Assert has a half-life of 25 to 45 days in
soil.
Ecol ogical Characteri stics :
Avian Acute Toxicity (Mallard Duck) > 2150 mg/kg
Avian Dietary Toxicity (Bobwhite Quail) > 5000 ppm
Avian Dietary Toxicity (Mallard Duck) > 5000 ppm
96-Hour Fish Toxicity (Rainbow Trout) > 100 mg/l
96-Hour Fish Toxicity (Bluegill Sunfish) > 100 mg/i
48-Hour Invertebrate Toxicity ( Daphnia magna > 100 mg/i
48-Hour Acute Toxicity (Honey Bee) > 100 ug/bee
Assert demonstrates negligible toxicity to birds on both an acute and
dietary basis. It is nontoxic to fish and invertebrates. It is not
expected to adversely affect endangered/threatened species because
of low toxicity.
Tol erance Assessment :
The nature of the residue is adequately understood, and adequate
analytical methods (gas—liquid chromatography with a nitrogen
sensitive detector) are available for enforcement purposes.
Tolerances are established for residues of the herbicide AC 222,293
EAssert, a mixture of methyl-2--(isopropyl—4-methyl-5-OXO-2-imidaZOlifl—
2-yl )-p-toluate and methyl-6-(4—isopropyl—4—methyl—5-OxO-2-imidaZOlin—
2-yl)—m—toluate] in or on the raw agricultural commodities sunflower
seed at 0.10 parts per million (ppm), wheat grain and barley grain
at 0.10 ppm, and wheat straw and barley straw at 2.00 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 0.0625 mg/kg/day. The theoretical maximum
residue contribution for these tolerances for a diet is calculated
to be 0.00147 mg/kg/day. The current action will use 2.35 percent
of the ADI. There are no other published tolerances for this chemical.
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4. Summary of Regulatory Position and Rationale
None of the risk criteria listed in 40 CFR 154.7 have been exceeded
for Assert. The Agency will issue a registration for this product.
Rationale : A review of available data indicate that no risk criteria
have been exceeded or met for Assert.
The Agency is not imposing a ground water advisory statement for
Assert.
Rationale : As the study was carried out, no residues were detected
below the 3—inch soil layer. If residues are found to leach within
the soil the Agency will request more data.
Additional residue data are not required to support the use on wheat
Straw.
Rationale : The Agency has determined that available residue data
adequately support the established tolerance on wheat straw.
The agency is requiring additional field dissipation studies to be
submitted by 1990.
Rationale : Assert has potential to leach and contaminate groundwater
at very low concentrations.
4.Summary of Major Data Gaps
None.
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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 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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