Metsulfuron Methyl - Herbicide Profile 3/86
CHEMICAL FACT SHEET FOR:
FACT SHEET NUMBER: 71
DATE ISSUED: MARCH 28, 1986
1. DESCRIPTION OF CHEMICAL
- Generic Name: Methyl-2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-
- Common Name: metsulfuron methyl
- Trade Name: DuPont Ally Herbicide, DuPont Escort Herbicide
- EPA Shaughnessy Code: 122010
- Chemical Abstracts Service (CAS) Number: 74223-64-6
- Year of Initial Registration: 1986
- Pesticide Type: Herbicide
- Chemical Family: Sulfonyl urea
- U.S. and Foreign Producers: E. I. duPont de Nemours & Company
2. USE PATTERNS AND FORMULATIONS
- Application sites: Wheat and barley, fallow or noncropland
- Formulations: 60% dry flowable (DF)
- Types and methods of application: Foliar postemergence application,
soil application to fallow land. Application may be made by ground
or aerial equipment.
- Application rates: 1/10 ounce active ingredient/acre (oz. a.i./A)
for wheat and barley. 1/3 to 2 oz. a.i./A for noncropland.
3. SCIENCE FINDINGS
- Physical state: Solid
- Color: Technical, white to pale yellow. 60% DF formulation,
- Odor: Technical, faint, sweet ester-like. 60% DF formulation,
- Melting point: 158 C.
- Specific gravity: 1.47 grams per cubic centimeter
- Molecular weight: 381.40
- Solubility: In distilled water at 25 C, 109 mg/L. In 0.05N
sodium phosphate buffer at 25 C as a function of pH: pH 6.7 =
9500 mg/L; pH 5.4 = 1750 mg/L; pH 4.6 270 mg/L. In organic
solvents at 20 C: n-hexane 0.79 mg/L; methylene chloride =
121,000 mg/L; acetone 3600 mg/L; methanol s 7300 mg/L; ethanol =
2300 mg/L; and xylene = 580 mg/L.
- Unusual handling characteristics: No special handling needed.
- Acute studies:
- Acute oral toxicity (rat): Greater than 5,000 mg/kg, Toxicity
- Acute dermal toxicity (rabbit): Greater than 2,000 mg/kg,
Toxicity Category III
- Primary dermal irritation: Slightly irritating, Toxicity
- Primary eye irritation: Corneal opacity in one unwashed eye
at 24 hours. Cleared in 48 hours. Toxicity Category III.
- Dermal sensitization (guinea pig): No sensitization shown,
Toxicity Category IV
- Label statements 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
- Label statements for 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.
- No precautionary labeling statements required for Toxicity
- Major routes of exposure: dermal and eye contact.
- Chronic studies:
- 2-year feeding/oncogenicity (rat): Systemic No-Observable-
Effect-Level (NOEL) = 500 ppm. Systemic Lowest Effect Level
(LEL) = 5,000 ppm. No oncogenic effects noted at 5,000 ppm
(highest dose tested (HDT)).
- 18-month oncogenicity (mice): Systemic NOEL = 5,000 ppm. No
oncogenic effects noted at 5,000 ppm (HDT).
- 1-year feeding (dog): NOEL = 50 ppm. LEL = 500 ppm.
- Teratology (rat): Maternal toxic NOEL less than 40 mg/kg/day.
Fetal toxic NOEL < 1,000 mg/kg/day. No teratogenic effects at
1,000 mg/kg/day (HOT).
- Teratology (rabbit): Maternal toxic NOEL 25 mg/kg/day.
Maternal toxic LEL 100 mg/kg/day. Fetotoxic NOEL 700
mg/kg/day. No teratogenic effects at 700 mg/kg/day (HDT).
- 2-generation reproduction (rat): Fetotoxic NOEL 5,000 ppm.
Maternal NOEL = 500 ppm. Maternal LEL 5,000 ppm. No
reproductive effects at 5,000 ppm (HDT).
- Mutagenicity (Salmonella typhimurium): negative
- Mutagenicity, chromosomal aberrations (CHO) in vitro:
Aberrations in Chinese hamster chromosomes were caused with
and without activation.
- Mutagenicity, unscheduled DNA synthesis (rat): Negative. Not
- Metabolism (rat): Rapid elimination of radioactivity, 91% or
over 96 hours.
Physiological and Biochemical Behavioral Characteristics
- Foliar absorption: Rapid
- Translocation: Systemic after absorption by foliage or roots.
- Mechanism of pesticidal action: Inhibition of cell division in
rapidly growing tips of roots and shoots by inhibition of
amino acid synthesis.
- Potential to contaminate groundwater: Metsulfuron methyl has the
potential to contaminate groundwater at very low concentrations.
- Metabolism in plants and animals: Metabolized to several non-
- Persistence in plants and animals: Does not persist in either
plants or animals.
- Absorption and leaching in basic soil types: Moderately to very
mobile, depending on organic matter content and soil texture.
Leaches through silt loam and sandy soils.
- Microbial breakdown: Degrades under anaerobic conditions to lower
molecular weight compounds.
- Loss from photodecomposition and volatilization: None
- Bioaccumulation: Does not accumulate in fish.
- Resultant average persistence: Half-life of 120 to 180 days in
silt loam soil.
- Avian acute oral toxicity (mallard duck): 2,150 mg/kg
- Avian 8-day dietary toxicity (mallard duck): 5,620 ppm
- Avian 8-day dietary toxicity (bobwhite quail): 5,620 ppm
_ fish acute 96-hour toxicity (rainbow trout): 150 ppm
- Fish acute 96-hour toxicity (bluegill sunfish): 150 ppm
- Invertebrate 48-hour acute toxicity (Daphnia magna): 150 ppm
- Honeybee acute toxicity (Apis): 25 ug/bee
- Available data indicate metsulfuron methyl is practically nontoxic
to birds, fish, invertebrates, and honeybees.
- The nature of the residue in plants and animals is adequately
understood, and adequate analytical methods are available for
- Tolerances are established for the combined residues of
metsulfuron methyl (methyl 2-[[[[4-methoxy-6-methyl-1,3,5-triazin-
2-yl)amino]carbonyl]amino]sulfonyl]benzoate) and its metabolite,
amino]sulfonyl]-4-hydroxybenzoate, in or on the following raw
Commodity Parts per million
Wheat, grain 0.05
Wheat, green forage 5.0
Wheat, hay 20.0
Wheat, straw 0.1
Barley, grain 0.05
Barley, green forage 5.0
Barley, hay 20.0
Barley, straw 0.1
- Tolerances are established for residues of metsulfuron in or on
the following raw agricultural commodities:
Commodity Parts per million
Cattle, fat 0.1
Cattle meat 0.1
Cattle meat byproducts 0.1
Goats, fat 0.1
Goats meat 0.1
Goats meat byproducts 0.1
Hogs, fat 0.1
Hogs, meat 0.1
Hogs, meat byproducts 0.1
Horses, fat 0.1
Horses, meat 0.1
Horses, meat byproducts 0.1
Sheep, fat 0.1
Sheep, meat 0.1
Sheep, meat byproducts 0.1
- The Acceptable Daily Intake (ADI) based on the 1-year dog feeding
study (NOEL of 1.25 mg/kg/day) and using a 100-fold safety factor
is calculated to be 0.0125 mg/kg/day. The Maximum Permissible
Intake (MPI) for a 60-kg human is calculated to be 0.75 mg/kg/day.
The Theoretical Maximum Residue Contribution (TMRC) for these
tolerances for a 1.5 kg diet is calculated to be 0.0455 mg/kg/day
(1.5 kg). The current action will use 6.06% of the ADI. There
are no published tolerances for this chemical.
Summary Science Statement
All data are acceptable to the Agency. It has low toxicity (Category
III) for acute dermal and primary eye irritation, and is even less toxic
(Category IV) for all other forms of acute toxicity. It was not
oncogenic to rats or mice, not teratogenic to rats or rabbits, and not
mutagenic with Salmonella or unscheduled DNA synthesis in rats. The
pesticide is foliarly and root absorbed, and translocated by the plant.
It works by inhibition of cell division in the shoots or roots. The
pesticide will leach in some soils. Metsulfuron methyl is practically
nontoxic to birds, fish, invertebrates, and honeybees. The nature of
the residue in plants and animals is adequately understood. and adequate
methodology is available for enforcements of tolerances in barley and
wheat grain; green forage of barley and wheat; hay of barley and wheat;
straw of barley and wheat; meat, fat, and meat byproducts of cattle,
goats, hogs, horses, and sheep; and milk.
4. SUMMARY OF REGULATORY POSITION AND RATIONALE
The Agency has accepted the use of metsulfuron methyl for control of
weeds in wheat and barley. All major data requirements have been
5. SUMMARY OF MAJOR DATA GAPS
6. CONTACT PERSON AT EPA
Robert U. Taylor (PM-25)
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.