United States Office of Pesticides and Toxic Substances
Environmental Protection Office of Pesticide Programs (TS-766C)
Agency Washington. DC 20460
&EPA Pesticide
Fact Sheet
Name of Chemical: Fenbutatin-oxide
Reason for Issuance: zssuanee of Registration Standard
Date Issued: ,|fj| g |
Fact Sheet Number: 119
1. Description of Chemical
-Generic Name: bis{tris(2-methyl-2-phenylpropyl)tin] oxide or
hexakis(2-methyl-2-phenylpropyl)-distannoxane
-Common Name: Fenbutatin-oxide
-Trade Name: Vendex, Fenbutatin oxyde, SD 14114, Torque,
Neostanox, and Osadan
-EPA Shaughnessy Number: 104601
Fenbutatin-oxide
-Chemical Abstracts Service (CAS) Number: 13356-08-6
-Year of Initial Registration : 1974
-Pesticide Type: Acaricide
-Chemical Family: Organotin
-U.S. Producer: E.I. duPont de Nemours and Company
2. Use Patterns and Formulations
-Application sites: fruit, field crops, and ornamentals
-Types and method of applications: Foliar application by
ground equipment only
-Application rates: 0.5 to 2.0 Ib a.i. per acre
-Types of formulations: technical, wettable powder and flowable
concentrate
-Usual carriers: Confidential Business Information
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3. Science Findings
Chemical Characteristics :
Technical fenbutatin—oxide is a white crystalline solid
with a melting point at around 145°C, that is insoruble in wat er
and slightly soluble in aromatic solvents. The empirical formula
is C 60 H 78 0Sn 2 and the molecular weight is 1053.
Toxicological Characteristics :
—Acute Oral: Data Gap
-Acute Dermal: >2000 mg/kg (rabbit)
—Primary Eye Irritation: Severe eye irritant (rabbit), Toxicity
Category I
—Acute Inhalation: Data Gap
—Primary Skin Irritation: Mild skin irritant (rabbit)
—Dermal Sensitization: Not a dermal sensitizer (guinea pig)
—Major routes of exposure: Dermal followed by inhalation—
Human exposure occurs from mixing, loading and application
Exposure can be reduced by the use of goggles or face
shield and protective clothing.
—Oncogenicity: A rat chronic/oncogenicity study showed no
oncogenic effects at the highest dose tested (600 ppm).
Mouse oncogenicity study: Data Gap
—Metabolism: Data Gap
—Teratology: Not teratogenic in rats (No Effect Level of
60 mg/kg with highest dose tested) or rabbits (No Effect
Level of 5 mg/kg).
—Reproduction: Data Gap
—Mutagenicity: Data Gap
Physiological and Biochemical Characteristics
—Mechanism of Pesticide Action: It is suspected that
fenbutatin—oxide inhibits adenosine triphosphate (ATP) enzymes.
That is, it paralyzes the insects cardiovascular and respiratory
systems by inhibiting oxidative phosphorylation.
—Metabolism and perisistence in plants and animals:
Available data demonstrate that fenbutatin—oxide is relatively
persistent on leaf surfaces and fruit and is gradually
degraded to dihydroxy-bis—( 2—methyl—2—phenylpropyl)
stannane, 2—methyl—2—phenylpropyl stannonic acid and
inorganic tin. Although submitted metabolism studies are not
adequate to assess the nature of fenbutatin—oxide in animals,
metabolites of fenbutatin—oxide were identified in feces of
dairy cattle.
Environmental Characteristics
—Available data are insufficient to fully assess the environ-
mental fate of fenbutatin—oxide. Data gaps exist for all
required studies. The data required in this Standard will also
allow us to assess the potential of this pesticide to cori
taminate groundwater.
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Ecological Characteristics
—Acute avian oral toxicity: LD 50 > 2510 mg/kg for Bobwhite
Quail (nontoxic).
—Avian dietary toxicity: LC 50 > 5620ppm for Mallard Duck
(nontoxic). Supplemental data indicate an LC 50 of 5065 ppm
for Bobwhite Quail (nontoxic).
—Freshwater fish acute toxicity: LC 50 = 0.0017 ppm for
Rainbow trout (very highly toxic). LC 5 Q = 0.0048 ppm for
Bluegill sunfish (very highly toxic).
Freshwater aquatic invertebrate toxicity: Supplemental data
indicate that an LD 50 value for freshwater invertebrates is
0.040 ppm (very highly toxic).
Tolerance Assessment
—Tolerances have been established for residues of fenbutatin—oxide
in a variety of raw agricultural commodities including meat,
fat and meat by products (refer to 40 CFR 180.362 for listing of
tolerances), and in processed food (21 CRF 193.236) and feed
(21 CFR 561.255).
—The Agency is unable to complete a full tolerance assessment
for the established tolerances due to residue chemistry and
toxicology data gaps.
Tolerances (ppm) (MRL)
Commodity U.S. Canadian Mexican Codex
Almonds 0.5 —
Almonds, hulls 80.0 — —
Apples 15.0 3.0 5.0
Cattle,fat 0.5 — —
Cattle,meat 0.5
by product
Cattle,meat 0.5 0.02
Cherries,sour 6.0 5.0
Cherries,sweet 6.0 — 5.0
Citrus fruits 2.0 2.0 5.0
Cucumber 4.0 0.5 1.0
Eggplant 6.0 — 1.0
Eggs 0.1 —
Goats,fat 0.5
Goats,meat by 0.5
product
Goats,meat 0.5 —
Grapes 5.0 5.0
Hogs,fat 0.5 —
Hogs,meat by 0.5
products
Hogs,meat 0.5
Horses,fat 0.5
Horses,meat by 0.5
product
Horses,meat 0.5
milk fat 0.1
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Tolerances (ppm) (MRL)
Commodity U.S. Canadian Mexican Codex
Papayas 2.0
Pecans 0.5 —
Peaches 10.0 7.0
Pears 15.0
Plums 4.0 3.0
Pou ltry,fat 0.1 —
Poultry, meat by 0.1
products
Poultry,meat 0.1
Prunes 4.0
Sheep,fat 0.5
Sheep, meat by 0.5
products
Sheep,meat 0.5
Strawberries 10.0
Walnuts 0.5
Apple pomace,dried 20.0
Citrus pulp,dried 7.0
Grape pomace,dried 100
Raisin waste 20.0
Prunes,dried 8.0
Raisins 20.0
—The data for the combined residues of fenbutatin—oxide and its
organotin metabolites in or on almonds, almond hulls, apples,
cherries(sweet and sour), citrus fruits, eggplant, grapes, papayas,
peaches, pears, pecans, plums, raspberries, strawberries and
walnuts are adequate to support the established tolerances.
—Data are not adequate to support the established tolerance for
residues in or on cucumbers. Processing studies are required
for apples, citrus fruits, grapes and plums.
—An acceptable Daily Intake (ADI) of 0.05 mg/kg/day, based a
2 year rat study has been established using a J 00 fold safety
factor. The Maximum Permissible Intake (MPI) is 3.0 mg/kg/day
for a 60 kg person. The Theoretical Maximum Residue
Contribution (TMRC) to the human diet from the existing
tolerances is 0.0357 mg/kg/day for a 1.5 kg diet which is 71.4%
of the MPI.
4. Summary of Regulatory Position
A. The Agency is requiring the submission of acute aquatic
toxicity data and aquatic field monitoring data on the
end—use formulations and aquatic life stage data and avian
reproduction data on the technical formulation in order to
complete the wildlife risk assessment.
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B. Because of California incidence reports and the
fact that this chemical is acutely toxic due to adverse
eye effects, the Agency is requiring a 24 hour reentry
interval, as established by California and Texas, until
the Agency has received and evaluated the required
reentry data.
C. Because of acute toxicity (eye effects), the Agency is
requiring that all fenbutatin—oxide product labels contain
protective clothing statements for early reentry.
D. No new tolerances or new food uses will be granted until
the Agency has received data to evaluate dietary exposure to
fenbutatin—oxide.
E. Based on fenbutatin—oxide use pattern and toxicity data,
the Agency, in cooperation with the Fish and Wildlife Service,
has determined that fenbutatin—oxide does not trigger
endangered species concerns at this time. No endangered
species labeling is required. If the required monitoring data
indicate a hazard, then a re—evalution will be conducted.
F. The Agency has determined that the following data are
essential to the Agency’s assessment and should receive a
priority review as soon as they are received by the Agency:
158.140 Reentry Protection
132—1 Foliar Dissipation (Re—entry)
158.145 Ecological Effects
72—4 Fish Early Life Stage and Aquatic Invertebrate
Life Cycle
72—3 Acute Toxicity— Aquatic Estuarine and Marine Organism
72—7 Field Testing for Aquatic Organism
G. The Agency is requiring that the fenbutatin—oxide organotin
metabolites be listed separately in the tolerance regulation
so that established tolerances can be made compatible with
the Maximum Residue Limits established by the Codex Alimentarius
Commission.
5. Sunimary of Major Data Gaps
—The following studies are required to assess the toxicological
characteristics of technical fenbutatin—oxide:
Acute Oral, Acute Inhalation, 90 Day Feeding (non—rodent),
21 Day Dermal Toxicity, Chronic Toxicity (non—rodent),
Oncogenicity (mouse), 2 Generation Reproduction, Mutagenicity and
General Metabolism Testing.
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—The following data are required to fully characterize
fenbutatin—oxide’s environmental fate: Re—entry (foliar
dissipation), Hydrolysis, Photodegradation (in water and on soil),
Aerobic and Anaerobic Soil Metabolism, Leaching, Volatility (Lab),
Soil Dissipation, Rotational Crops (Confined), and Accumulation
in fish.
—Additional residue studies on commodities, animal metabolism
studies, and storage stability studies are required to support
existing tolerances.
—The following data are required to complete a wildlife risk
assessment: Avian Subacute Dietary Toxicity, Avian Reproduction,
Freshwater Fish Toxicity, Acute Toxicity to Freshwater
Invertebrates, Acute Toxicity to Estuarine and Marine Organisms,
Fish Early Life Stage and Aquatic Invertebrate Life Cycle,
Aquatic Organism Accumulation Testing, and Simulated or Actual
Field testing for Aquatic Organisms.
—Product Chemistry and Acute toxicity data are required.
Contact person at EPA:
Dennis Edwards
Product Manager (12)
Insecticide—Rodenticide Branch
Registration Division (TS—767C)
Office of Pesticide Programs
Environmental Protection Agency
401 14. Street, S.W.
Washingtori,D.C. 20460
Office location and telephone number:
Room 202, Crystal Mall Building 2
1921 Jefferson Davis Highway
Arlington,Va. 22202
703—557—2386
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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