UniieU Sidics Office of Pesi'Cides
Environmental Proieciion and Toxic Subsiances
Agency (H7501C) —.
540/FS-90-091
EPA Pesticide
Fact Sheet
Name of Chemical: Suifosate
Reason for Issuance: New Chemical Registration
Date Issued: ^ ® ^
Fact Sheet Number: 213
1. Description of Chemical
Common Name: Sulfosate
Chemical Name: N-phosphonomethylglycine trimethylsulfonium salt
Code Name: SC-0224
Trade Name: Touchdown
OPt> (Shaughnessy) Number: 128501
Chemical Abstracts Service (CAS) Number: 81591-81-3
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Year of Initial Registration: 1989
Pesticide Type: Herbicide
U.S. and Foreign Producers: ICI Americas Inc.
2. IIsp Pattpms ^rki Formi 1 at int\<=.
Applications Sites: Noncrop areas around the farm such as: farmyards,
fuel storage areas, fence rows, rights-of-way, soil b^nk land, and
barrier strips
Types and Methods of Application: Application is by spray, wiper or
hand-directed spot applications to the foliage of actively growing
weeds. Aerial application is prohibited.
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Pcots Controlled: Broadleaf and grass weeds
Application Rates: Application rates range from a 1% solution up to
4.12 pounds active ingredient (ai)/A, depending on target weed and
type of application.
Types of Formulations: 39.9% ai (4 lbs ai/gal) and 52.2% ai (5.5 lbs
ai/gal) liquid concentrate
Usual Carriers: Water and surfactant
3. Science Findings
Summary Science Statement:
Asple toxioological, environmental fate, ecological effects and
product chemistry data have been submitted to support the non-crqp use
of sulfosate. Based on acute toxicity studies, sulfosate is classified
as Toxicity Category III, signal word CAUTION. Sulfosate is not
developmentally toxic and was non-rautagenic in the Ames assay. The
chemical is practically nontoxic to fish but slightly toxic to aquatic
invertebrates. Sulfosate is practically nontoxic to birds based on
dietary studies, but is slightly toxic to birds on an acute oral basis
(mallard duck). The ctiemical is essentially nontoxic to honey bees.
Sulfosate is stable to hydrolysis and aqueous photolysis. Sulfosate
degrades reasonably fast in soil under both aerobic and anaerobic
conditions. The chemical is not likely to leach and contaminate groundwater
ur/ter actual use conditions.
Chemical Characteristics:
Physical state: liquid
Color: brownish-amber
Odor: Faint, sulfur odor
Boiling point: 109* C
Density: 1.27 g/cc
Vapor pressure:
7.2 mm Hg at 10* C
13.3 mm Hg at 20* C
23.6 mm Hg at 30* C
Vapor pressure of the active ingredient in
aqueous solution: 3 X 10~7 mm Hg at 25* C
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pH: 5.2 - 5.6 (neat), 3.9 - 4.3 (dilute)
Viscosity: 38.2 centistokes at 25* C
Molar water solubility (pure active ingredient): 17.6 X 10^ g
Octanol/water partition coefficient (K^): less than 10, no
sulfosate C<0.1 part per million (ppm)] in the octanol phase
Stability: No apparent degradation, even at elevated tenperatures
(52* C) or periods of up to 12 weeks.
Unusual handling characteristics: Do not mix or store sulfosate
in galvanized steel or unlined steel containers.
Toxicology Characteristics:
Acute Toxicity (Technical)
Acute oral toxicity (rat): 748 mg/kg (males), 755 mg/kg (females),
Toxicity Category III, (62% ai)
Acute dermal toxicity (rabbit): greater than 2,000 mg/kg,
Toxicity Category III, (62% ai)
Primary skin irritation (rabbit): a mild dermal irritant,
Toxicity Category IV, (62% ai)
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Primary eye irritation (rabbit): mild irritation to conjunctivae,
irritation is reduced by washing. Toxicity Category III, (62% ai)
Acute inhalation toxicity (rat); greater than 0.81 wqfh for a
4-hour exposure, Toxicity Category III, (56.2% ai)
Dermal sensitization (guinea pig): results indicate that sulfosate
is a mild sensitizer, (56.3% ai)
Acute Toxicity (ToucWown 4-LC, 39.9% ai)
Acute oral toxicity (rat): 1,760 mg/kg (males), 1,298 mg/kg (females).
Toxicity Category III
Acute dermal toxicity (rabbit): greater than 2,000 mg/kg (males/
females). Toxicity Category III
Dermal irritation (rabbit): a non-irritant in intact skin of rabbits
after 4 hours of exposure, Toxicity Category IV
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Eye irritation (rabbit): a moderate irritant, clearing by day 7,
"toxicity Category III
Dermal sensitization (guinea pig): not a dermal sensitizer
Subchronic Toxicity
h 21-day dermal study in rabbits was conducted using dose levels of
0, 10, 100 and 1,000 mg/kg/day. A slight dermal irritation was
observed in males and females at all dose levels. However, this
finding did not ooqprcmise the results of the study. Ttie no-
observable-effeet-level (NOEL) is greater than or equal to
1,000 mg/kg/day for systemic toxicity (highest dose tested [HOT]).
Teratology
A teratology study in rabbits was conducted with dose levels of 0,
10, 40 and 100 mg/kg/day. A NOEL for maternal toxicity was not
determined. The lowest-observed-effect-level (D0EL) for maternal
toxicity was 10 mg/kg/day. A NOEL based on increased maternal
mortality and spontaneous abortion was 40 mg/kg/day.
Teratogenicity was not observed in a rat teratology study using
dose levels of 0, 30, 100 and 333 rag/kg/day. Maternal toxicity,
seen as reduced body weights and feed was demonstrated in the
high dose group (333 mg/kg). Fetotoxicity, as evident by
reduced fetal body weight in the high dose group, apparently
resulted from maternal toxicity.
Mutagenicity
Sulfosate was non-nutagenic in the Ames assay, at the concentrations
tested, 2.5 through 40 ul/plate.
Sulfosate was mutagenic in the mouse lynphoroa nutation assay
under normal test conditions and at the concentrations tested,
3.0-5.0 ul/ml with metabolic activation and 3.5-5.0 ui/ral without
metabolic activation.
Results from cytogenic assays (chromosomal aberration and sister
chromatid exchange) indicate that sulfosate was not a clastogenic
agent and did not induce any increase of mutant frequency in the
cultured L5178Y mouse lyipboce cell system, with and without
metabolic activation (under the pH-adjusted test oonditions
[pH 7.4] and at the concentrations tested, 4-10 ul/ml). Sulfosate
was not a clastogenic agent in the cultured CHO (Chinese Hamster
Ovary Cell) system with and without metabolic activation at the
concentrations tested, 4-10 ul/ml.
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Major routes of exposure: Mixers, loaders and applicators would
receive the most exposure via skin/eye contact and inhalation.
Physiological and Biochemical Behavioral Characteristics
Foliar absorption: Sulfosate is absorbed in the foliage
Mechanism of pesticide action: systemic
Environmental Characteristics:
Hydrolysis: Sulfosate does not hydrolyze at pH 5 - 9.
Aqueous photolysis: Hie anion portion of sulfosate, N-phosphono-
methylglycine (PM3), has half-lives of 14.6, 77.9 and 41.6
days at pH 5, 7 and 9, respectively. Ftootoproducts were
phosphoric acid and aminoroethylphosphonic acid. Hie
trimethylsulfonium (IMS) cation was stable at pH 5 and 7,
but degraded with a half-life of 31.7 days at pH 9.
Aerobic soil metabolism: Hie IMS moiety of sulfosate has a half-
life of 2-3 weeks. Hie major degradate is CX>2- The PMG moiety
of sulfosate has a half-life of 2-3 days. Hie major degradate
is amincnethylphosphonate (AMP).
Leaching, adsorpticn/desorption: Sulfosate exhibits lew nobility in
soil. Hie PMG moiety and its degradate, AMP, are immobile. Hie
TMS moiety has moderate nobility in soil.
Field dissipation: Field dissipation studies conducted in Virginia,
Florida, California, Iowa and Mississippi indicate that the PMG
moiety and its degradate AMP have a low leaching potential. Hie
IMS moiety has a moderate leaching potential.
Fish accumulation: Hiis data requirement has been waived, based on
sulfosate's high water solubility and low octanol/water partition
coefficient, K^.
Potential to contaminate groundwater: TMS has a moderate propensity
for leaching but degrades reasonably fast to 2 in soil under
both aerobic (half-life of 2 months) and anaerobic (half-life
of 2-3 weeks) conditions. Hierefore, "IMS residues are not
likely to leach and contaminate groundwater under actual use
conditions. Available data indicate that PMG has low leaching
potential.
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Ecological Characieristies:
Technical Sulfosate (58.5% ai)
Avian acute oral toxicity:
Mallard duck 950 mg/kg
Avian dietary toxicity:
Mallard duds greater than 5,000 ppm
Bobwhite quail greater than 5,000 ppm
Fish acute toxicity:
Rainbow trout 1,800 rag/L
Bluegill sunfish 3,500 mg/L
Aquatic invertebrate toxicity:
Daphnia magna 71 wq/h
Sulfosate 4-LC (39.9% ai)
Fish acute toxicity:
Rainbow trout 603 mg/L
Bluegill sunfish 297 mg/L
Acute toxicity to honey bees: 62.1 micrograms per bee
The above studies indicate that sulfosate is practically nontoxic
to birds on a dietary basis, slightly toxic to Mallar-d ducks on an
acute oral basis and slightly toxic to D. magna. Sulfosate is
practically non-toxic to fish. The 4-LC formulation is considered
to be practically non-toxic to fish, and essentially nontoxic to
honey bees.
A rainbow trout early life stage and D. wacpa life cycle test were
conducted using sulfosate 4-LC. Both studies are classified
Core.
Potential problems related to endangered species: No endangered
species review is needed for this product at this time because
of its substantial similarity to glyphosate which is registered
for numerous uses. The Agency will consult with the U. S.
Fish and Wildlife Service to discuss if any species would be in
jeopardy under other registrations for sulfosate.
This review will be conducted under the new endangered species
approach (species-based) after implementation of the program.
Surnnary of Regulatory Position and Rationale
The available data provide sufficient information to support the conditional
registration of Touchdown 4LC and unconditional registration of Touchdown
Concentrate on nonerop areas around the farm.
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Use, formulation, manufacturing process or geographical
restrictions: Aerial application is prohibited on the label.
5- Summary of Major Data Gaps
Acute Inhalation Study (4-LC formulation)
21-Day Dermal Study (4-LC formulation)
6> OCNTACT PERSON AT EPA
Robert J. Taylor
Product Manager (25)
Fungicide-Herbicide Branch
Registration Division (H7505C)
Office of Pesticide Programs
Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
Office location and telephone number:
Room 243, Crystal Mall #2
1921 Jefferson Davis Highway
Arlington, VA 22202
(703) 557-1800
DISCLAIMER: Itie information in this Pesticide Fact Sheet is a summary only
and is not to be used to satisfy data requirements for pesticide registration
and reregistration. Hie oonplete Registration Standard for the pesticide may be
obtained from the contact person listed above.
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