United States Office of Pertiodw end Toxic Suteunees
Environmentil Proteetton Office of Pertidde Progremt (T8-766CI
Agency Washington, DC 20460
v>EPA Pesticide
Fact Sheet
Name Of Chemical: Metsulfuron methyl
Reason for Issuance: New Chemical Registration
Date Issued: March 28, i°86
Fact Sheet Number: 7i
1. Description of chemical
Generic name: Methyl-2-]]]](4-methoxy-6-methyl-l,3,5-triazin-2-yl)
amlno]carbonyl ]amino ]sulf onyl ]benzoate
Common name: Metsulfuron methyl
Trade name: DuPont Ally Herbicide, DuPont Escort Herbicide
EPA Shaughnessy code: 122010
Chemical Abstracts Service (CAS) number: 7^223-61-6
Year of Initial registration: 1986
Pesticide type: Herbicide
Chemical family: Sulfonyl urea
U.S. and foreign producers: E. I. du Pont de Nemours & Company
2. Use patterns and formulations
Application sites: Wheat and barley, fallow or noncropland
Formulations: 60% dry flowable (DP)
Types and method 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 ai/A)
for wheat and barley
1/3 to 2 oz/ai/A for noncropland
3. Science findings
Summary science statement; All data are acceptable to the Agency. It ,
has low toxlcity (Category III) for acute dermal and primary eye irrita-
tion and is even less toxic (Category IV) for all other forms of acute
toxlcity. It was not oncogenlc to rats or mice, not teratogenic to
rats or rabbits, and not mutagenic with Salmonella or unscheduled DNA
synthesis In rats. The pesticide is follarly 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
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honeybees. The nature of the residue in plants and animals is adequately
understood and adequate methodoloqy is available for enforcements of
tolerances in barley and wheat grain; green foraqe 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.
Chemical Characteristics
Physical state: solid
Color: Technical - white to pale yellow
60% DF formulation - off white
Odor: Technical — faint, sweet ester—like
60% DF formulation - odorless
Melting point: 158 °C
Specific gravity: 1.47 grams per cubic centimeter
Molecular weight: 381.40
solubility: In distilled water at 25 °C a 109 milliqrams/liter (mqfL).
In 0.05N sodium phosphate buffer at 25 °C as a function
of pH:
pH 6.7 9500 mqfL
pH 5.4 1750 mq/L
pH 4.6 270 mq/L
In organic solvents at 20 °C
n-hexane 0.79 mq/L
methylene chloride 121000 mq/L
acetone 3600 ma/L
methanol 7300 mq/L
ethanol 2300 mq/L
xylene 580 ma/L
Unusual Handling Characteristics: No special handling needed.
Toxicology Characteristics:
Acute Studies:
Acute Oral Toxicity (Rat)
Greater than C>) 5000 inilliqrains/kiloaran’ (mg/kg)
Toxicity Cateqory I v t !
Acute t)ermal Toxicity (Rabbit)
7 2000 ma/kg
Toxicity Category XII I!
Primary Dermal Irritation
Slightly Irritatinq
Toxicity Category 1V 1 !
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Primary Eye Irritation
Corneal opacity in one unwashed eye at 24 hours. Cleared in
48 hours.
Toxicity Category 1111/
Dermal Sensitization (Guinea pig)
No sensitization shown
Toxicity Category 1V 1 /
1 Label statements for Toxicity Cateqory III for acute dermal: 0 Harmful
if absorbed through skin. Avoid contact with skin, eyes, or clothinq.
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 labelinq statements required.
Major Routes of cposure:
The major routes of exposure are through dermal and eye contact.
Chronic Studies:
2—Year Feedinq/OncoqenicitV (Rat)
Systemic no—observable—effect level (NOEL) 500 parts per million
(ppm)
systemic lowest effect level (LEt) 5000 ppm
No oncoqenic effects noted at 5000 ppm [ highest dose tested (HOT)).
18—Month Oncoqenicity (Mice)
Systemic NOEL = 5000 ppm
No oncogenic effects noted at 5000 ppm (HDT)
1-Year Feeding (Dog)
NOEL = 50 ppm
LEt = 500 ppm
Teratology (Rat)
Maternal toxic NOEL less than (<) 40 mg/kg/day
Fetal toxic NOEL < 1000 mg/kg/day
No teratoqenic effects at 1000 mg/kg/day (HOT)
Teratology (Rabbit)
Maternal toxic NOEL = 25 mg/kq/dav
Maternal toxic LEt = 100 mg/kg/day
Fetotoxic NOEL > 700 mg/kg/day
No teratoqenic effects at 700 mq/kq/day (HOT)
2—Generation Reproduction (Rat)
Fetotoxic NOEL > 5000 ppm
Maternal NOEL = 500 ppm
Maternal LEt = ‘5000 ppm
No reproductive effects at 5000 ppm (HOT)
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Mutaqenicity—Salmonella typhiuturium - negative
Mutagenicity—chroinoscutal aberrations (CR0) in vitro - aberrations in
Chinese hamster chromosomes were caused with and without activation,
Mutagenicity—unscha uled DNA synthesis (rat) - negative — not mutagenic
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 ground water: Metsulfuron methv]. has the
potential to contaminate ground water at very low concentrations.
Metabolism in plants and animals: metabolized to several nonherbicidal
c pounds.
Persistence in plants and animals: does not persist in either animals
or plants.
bivironmental Characteristics
Msorption and leaching in basic soil types: moderately to very
mobile depending on organic matter content and soil texture.
Leaches through silt loam and sand soils.
Microbial breakdown: deqrades under anaerobic conditions to lower
molecular weight compounds.
Loss from pk otodecomposition and volatilization — none.
Bioaccumulation — does not accumulate in fish.
Resultant average persistence — half-life of 120 to 180 days in silt
loam soil.
Ecoloqical Characteristics
Avian Acute Oral Toxicity (mallard duck) > 2150 mg/kg
Avian 8-day Dietary Toxicity (mallard duck) > 5620 ppm
Avian 8—day Dietary Toxicity (bobwhite auail) > 5620 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.
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Tolerance Assessment
The nature of the residue in plants and animals is adequately
understood, and adequate analytical methods are available for enforcement
purposes.
Tolerances are established for the combined residues of the metsulfuron
methyl (methyl 2-(((((4-methoxy—6—methyl—i ,3,5—triazin-2-yl)aminojcarbonylj
amino]sulfonyljbenzoate) and its metabolite, methyl 2— [ UU4—methoxy-6-
methyl—i ,3,5-triazin—2—yl)aminojcarbonyljamino)sulfonyl]—4 hydroxybenzoate,
in or on the following raw agricultural commodities:
Commodities 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 methyl (methyl—
2—((( [ (4—methoxy—6—methyl—1 , 3,5—triazin—2—yl)aminolcarbonyl)aminojsulfonylj
berizoate) in or on the followinq raw aqricultural commodities:
Commodities Parts Per Million
Cattle, fat 0.1
Cattle, meat 0.1
Cattle, meat byproducts 0.1
Goat, fat 0.1
Goat, meat 0.1
Goat, meat byproducts 0.1
Hoqs, fat 0.1
Hogs, meat 0.1
Hoqs, meat byproducts 0.1
Horses, fat 0.1
Horses, meat 0.1
Horses, meat byproducts 0.1
Milk 0.05
Sheep, fat 0.1
Sheep, meat 0.1
Sheep, meat byproducts 0.1
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The acceptable daily intake (ADI) based on the 1—year doa feedinq
study (NOEL of 1.25 mg/kg/day) and using a hundredfold 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 (T?4RC) 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 percent of the ADI. There are no published
tolerances for this chemical.
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
filled.
5. SUMMARY OF MAJOR DATA GAPS
None.
6. CONTACT PERSON AT EPA
Robert J. Taylor
Office of Pesticide Proqrams, EPA
Registration Division (TS—767C)
401 P4 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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