United Sttta,             wja| ^ ^1*1* and To*te SubMnea
                    Environmental Protection      office of Pettidde Program* (TS-766C)
                    A«ene*                 Wtahington, DC 20460
vvEPA       Pesticide
                    Fact Sheet
                    Name of Chemical:  CYHEXATIN
                   Reason for Issuance:
                    Date  Issued:  June 30, 1985
                    Fact Sheet Number:    56

     - Generic Name:  Tricyclohexylhydroxystannane
     - Cctmon Name:  Cyhexatin
     - Trade Name:  Plictran®, Acarstin® and Dowco® 213
     - EPA Shaughnessy Code:  101601
     - Chemical Abstract Service (CAS) Number:  13121-70-5
     - Year of Initial Registration:  1972
     - Pesticide Type:  Miticide
     - Chemical Family:  Organotins
     - U.S. Producer:  Dow Chemical Company


     - Application sites:   apples,  pears,  citrus, peaches, plums,
       nectarines, strawberries, almonds,  walnuts, hops, and
       ornamental plants (including greenhouse grown)
     - Types and methods of applications:  aerial and ground
       application as a spray
     - Application rates:   0.5 Ib active  ingredient (ai)/A
       to 2.0 Ibs ai/A
     - Usual Carriers:   wettable powders


     Chemical Characteristics

     -  Technical cyhexatin  is a white, crystalline powder, nearly
       odorless that  has no true melting point,  degrades to bistri-
       cyclohexyltin  oxide at 121 to 131° C and  decomposes at  228° C.
     -  It  is  soluble  in some organic solvents and  is very insoluble
       in  water.
     -  Vapor pressure  is negligible at 25° C, it is stable in
       aqueous suspensions in neutral and alkaline pH, reacts
       ionically in the presence of a strong  acid  to form salts,
       converts to  dicyclohexyltin  oxide and  further to cyclohexyl-
       stannoic acid by exposure to ultraviolet  radiation.

Toxicology Characteristics
— Acute oral: 196 mg/kg (rat), Toxicity Category II.
— AciJte dermal: Data gap.
— Primary Eye Irritation: Causes eye irritation——Cornea 1
and iris irritation (rabbit), Toxicity Category II.
— Acute Inhalation: 6.35 mg/i (rat), Toxicity Category III.
— Primary Skin Irritation: Nonirritant, Toxicity Category IV.
— Skin Sensitization: Not a sensitizer.
— Major Routes of Exposure: Human exposure from cyhexatin
applications is greatest from mixing and loading of pesticide
formulation and applying it. Exposure can be reduced by the
use of goggles or face shield and gloves and other protective
— NeurotOXiCity: Cyhexatin is not expected to be a delayed
neurotoxin because it is neither an organophosphate nor an
analog of a neurotOxic compound.
— OncogefliCity: Data gap. Study submitted does not meet Agency
— Metabolism: Available data suggest that cyhexatin is not
readily absorbed in tissues and is excreted in the feces.
The minor amount that is not excreted is metabolized to an
organotin form and is accumulated in the liver and kidney
with lesser levels found in the brain, heart, adrenal, and
— Teratology: Adequate data are unavailable. Data gap.
— Reproduction: Adequate data are unavailable. Data gap.
— Mutagenicity: Adequate data are unavailable. Data gap.
Physiological and Biochemical Characteristics
— Mechanism of pesticidal action: It is suspected that
cyhexatin inhibits adenosine triphosphate (ATP) enzymes.
— Metabolism and persistanCe in plants and animals: Available
data suggest that plant degradates of cyhexatin are trans—
located following root exposure, however these data are
insufficient to adequately characterize plant metabolism.
Known animal metabolism is summarized above.
Environmental Characteristics
— Available data are insufficient to fully assess the
environmental fate of cyhexatin. Data gaps exist for all
required studies.

— The available data do suggest that cyhexatin can leach
slowly in certain soils. Data are required to assess
cyhexatin’s environmental fate and ability to leach
through soils.
Ecological Characteristics
— Avian acute oral (LD 50 ) toxicity: approximately 250 my
to 400 mg technical cyhexatin/kg body weight for quail
(moderately toxic).
— Avian dietary (LC 50 ) toxicity: 195 ppm for bobwhite quail
(highly toxic).
— Freshwater fish acute (LC 50 ) toxicity: cold water species
(rainbow trout)——6 ppb for technical; warm water species
(bluegill)——4 ppb for technical.
— Aquatic freshwater invertebrates toxicity: Daphnia——0.2 ug/l.
— Additional data are required to fully characterize the
ecological effects of cyhexatin.
Required Unique Labeling Summary
All manufacturing—use and end—use cyhexatin products
must bear appropriate labeling as specified in 40 CFR 162.10.
In addition to the above, the following information must
appear on the labeling: -
— Manufacturing—use products must state that they are intended
for formulation into other manufacturing—use products or
end-use products for uses which are accepted by the Agency.
— Current labels must be revised to reduce the recommended
spray gallonage and active ingredient per acre for pears,
peaches, plums (prunes), and nectarines.
— Labels must be revised to incorporate the use of additional
protective clothing such as mask or respirators and chemically
resistant gloves.
Tolerance Assessment
— The Agency is unable to complete a full tolerance assessment
for the established tolerances because of certain residue
chemistry and significant toxicology data gaps.
— Established tolerances are published in 40 CFR 180.144 and
they are:

Comn,oth Parts Per Million
Almonds 0.5
Almonds, hulls 60
Apples 2
Cattle, fat 0.2
Cattle, kidney 0.5
Cattle, liver 0.5
Cattle, meat byproducts (rnbyp) 0.2
Cattle, meat 0.2
Citrus fruits 2
Goats, fat 0.2
Goats, kidney 0.5
Goats, liver 0.5
Goats, rnbyp 0.2
Goats, meat 0.2
Hogs, fat 0.2
Hogs, liver 0.5
Hogs, mbyp 0.2
Hogs, meat 0.2
HOps 30
Horses, fat 0.2
Horses, kidney 0.5
Horses, liver 0.5
Horses, mbyp 0.2
Horses, meat 0.2
Macadamia nuts 0.5
Milk, fat 0.05
Nectarines 4
Peaches 4
Pears 2
Plums (fresh prunes) 1
Sheep, fat 0.2
Sheep, kidney 0.5
Sheep, liver 0.5
Sheep, mbyp 0.2
Sheep, meat 0.2
Strawberries 3
Walnuts 0.5
— The data for cyhexatin residues in or on the following
agricultural commodities are adequate to support the residue
data requirements: hops, macadamia nuts, and strawberries.
— Additional residue data are required for the following
commodities: peaches, plums, nectarines, apples, pears,
almonds, almond hulls, walnuts, citrus fruits, dried hops
and meat, milk, poultry, and eçgs.
— based on the established tolerances the theoretical maximum
residue contribution (TMRC) for cyhexatin residues in the
human diet is 0.33 mg/day (for a 60 kg person with a 1.5 kg

diet). However, this was based on an acceptable daily
intake (ADI) which has been invalidated due to the lack of
a sufficient chronic toxicology data base.
— Compatability of U.S. tolerances with Codex Maximum
Residue Limits will be assessed when data have been submit-
ted and evaluated.
— The Agency has determined that it should continue to allow
the registration of cyhexatin. None of the criteria for
unreasonable adverse effects listed in the regulations
(S162.il(a)) have been met or exceeded. However, because
of gaps in the data base a full risk assessment cannot be
— Also, a full tolerance reassessment cannot be completed
because of major residue chemistry and toxicology data gaps.
Until these gaps are filled cyhexatin will not be registered
for significant new uses.
— Available data are insufficient to fully assess the environ-
mental fate of and the ecological effects from cyhexatin.
Data are required to determine if cyhexatin will contaminate
ground water.
— Additional crop residue studies on various commodities and
plant and animal metabolism studies are required to support
existing tolerances. The full compliment of chronic tox-
icology requirements are data gaps: chronic feeding,
oncogerlicity, reproduction, and teratology and mutagenicity.
— The full compliment of environmental fate data requirements
are data gaps. Studies on degradation (hydrolysis and
photolysis), soil metabolism, mobility, dissipation, and
accumulation are needed to fully characterize cyhexatin’s
environmental fate.
— Additional data are required on avian toxicology (acute and
subacute oral and reproduction) and freshwater and marine
organism acute toxicology.
— Other data gaps are product chemistry of technical cyhexatin,
storage stability of residues, and acute and subchronic
derrnal toxicology.

( ‘7
Jay S. Ellenberger
ProduQt Manager (12)
Insecticide_ROdenticide Branch
Registration DiviSiOfl (TS—767)
Office of pesticide Programs
Environmental Protection Agency
401 M Street SW.
Washington, DC 20460
Office location and telephone number:
Room 202, Crystal Mall Building 42
1921 Jefferson Davis Highway
Arlington, VA 22202
(703) 557—2386