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SEPA Pesticide
"Fact Sheet
Name of Chemical: resmethrin
Reason for Issuance: Re9istration standard
Date ISSued:December 1988
Fact Sheet Number: i 
Generic Name: [5-(phenylmethyl)-3-furanyl] methyl 2,2-dimethyl-
3- (2-methyl-l-propenyl) eyelcpropanecarboxylate
Catron Name: Resmethrin
Trade and Other Names: Synthrin, SPB-1382, Pynosect, Qirysran
ETA Shaughnessy Codes: 097801
Chemical Abstracts Service (CAS) Number: 10453-86-8
Year of Initial Registration: 1967
Pesticide Type: Insecticide
Chanical Family: Pyrethmoid
U.S. and Foreign Producers: Fairfield American - (HS)
Mitchell Cotts Chemical Ltd. (UK)
Fenick - Bio UCLAF corp. (us)
Sumitomo Qiemical Co. (Japan)

Application: Flying and crawling insect control for household, greenhouse,
indoor landscaping, mishroan houses, industrial, stored
product insects, and mosquito control. Resmethrin is also used
for fabric protection, pet sprays, pet shanpoos, and
application to horses and in horse stables. Resnethrin may be
used in USEA meat and poultry programs.
Types of Formulations: Resmethrin is primarily formulated into pressurized
liquids and ready-to-use solutions. It is also
formulated as an emulsifiable concentrate, soluble
concentrate, and on impregnated materials.
Surrmarv Science Statement
Chanical Characteristics of the Technical Material
Physical State: Waxy solid
Color: Off-white to tan
Odor: Chrysanthanate
Molecular Weight and Formula: 338.4
Boiling Point: 180^ at 0.1 nm Hg
Vapor Pressure: 2.58 rim Hg, 200C
Density: 8.70 lb/gal
Solubility in various solvents: Insoluble in water, 10% in kerosene, and
very soluble in xylene, methylene chloride,
isopropyl alcohol and aranatic hydrocarbons.

toxicology Characteristics
Acute Oral: ID50 - 750 to 4500 wq/kg
Acute Dermal: LD^q - 2500 mg/kg
Primary Dermal Irritation: Not considered to be a dermal irritant.
Primary Eye irritation: Not considered to be an eye irritant.
Dermal Sensitization: Not considered tOH 1. DBSCRIPTICN OF CHEMICAL
Generic Name: [5-(phenylmethyl)-3-furanyl] methyl 2,2-dimethyl-
3- (2-methyl-l-propenyl) eye lopropanecar boxy late
Ccrmon Name: Resmethrin
Trade and Other Names: Synthrin, SPB-1382, Pynosect, Chrysron
EPA Shaughnessy Codes: 097801
Chemical Abstracts Service (CAS) Nunber: 10453-86-8
Year of Initial Registration: 1967
Pesticide Type: Insecticide
Chemical Family: Pyrethroid
U.S. and Foreign Producers: Fairfield American (US)
Mitchell Cotts Chemical Ltd. (UK)
Penick - Bio UCLAF Corp. (US)
Sunitcmo Chauical Co. (Japan)

HaucQiogy Characteristics
Acute Oral: LD50 " 750 to 4500 ""^Ag
Acute Dermal: IO50 ~ 2500 ^Ag
Primary Dermal Irritation: Not considered to be a dermal irritant.
Primary E^e Irritation: Not considered to be an eye irritant.
Dermal Sensitization: Not considered to be a skin sensitizer.
Acute Inhalation: LC50 >9.49 mg/L (4 hr. exposure)
Major routes of exposure: dermal, eye, inhalation
Delayed neurotoxicity: Studies not required because resnethrin is not an
Subchronic toxicity: A 90-Day subchronic inhalation study in rats did not
demonstrate a definite NOEL. At the lowest dose tested,
0,1 mg/L, there was evidence of behavioral reactions to
treatment, decreased blood levels of glucose in males,
decreased body weights and increased serum urea levels
in females. 90-Day subchronic dermal studies are
required because currently registered use patterns (i.e.
veterinary use only animal shampoos) could result in
prolonged or repeated exposure to humans.
Chronic Feeding: A rodent (rat) study did not establish a NOEL. There
was seme evidence liver enlargement at the lowest dose
tested (500 ppn or 25mg/kg/day). At the tjt. of 2500 ppn
or 125 mg/kg/day, increased liver weigth and
pathological lesions in this organ were observed. At the
HOT of 5000 ppn, or 250 mg/kg/day, additional dose
related increases in liver weight, liver pathology, and
also increases in thyroid weight and incidences of
thyroid cysts were observed.
A dog chronic chronic study daronstrated a NOEL of 10

Oncogenicity: Resnethrin was determined not to be oncogenic for rats at
dosage levels up to and including 5000 ppn, and for mice at
dosage levels up to and including 1000 ppn.
Teratogenicity: Hie teratogenic NOEL for rats was 40 mg/kg/day based on
slight increase in aberrations in skeletal findings. Uiere
was an indefinite maternal MUX. with seme decrease in food
consumptions at all dose levels tested and a body weight
decrease at the 80 mg/kg/day level. Hie teratogenic, maternal
and fototoxic NOELs in the rabbit were greater than 100
mg/kg/day (HOT).
Reproduction: A definite NOEL was not established since there were
marginally statistically significant increases in the number
of pups born dead and decreases in pup weight at weaning at
the lowest dosage tested (500 Fpm or 25 mg/kg/day). The
observed effects were judged to be minimal whan the low dose
groups were compared with the controls.
Environmental Characteristics
Hie potential for resmethrin to contaminate groundwater is
unknown. However based on the non-leaching characteristics of
related pyrethriod ccnpounds and the fact that more than one-
half of the 30,000 lbs. used annually is used indoors, it is
not likely that use of this chemical will pose appreciable
risks to groundwater.
Avian acute toxicity: Resmethrin is slightly toxic to birds, the LD50 >
2000 mg/kg - California quail.
Freshwater fish acute toxicity: Resnethrin is very highly toxic to fish
(Bluegill IC50 - 0.75 - 2.6 ug/L and
Rainbow trout LC50 - 0.28 - 2.4 ug/L).
Freshwater and marine invertebrate toxicity:
Hie Agency does not have any data on invertebrates species,
but based an the characteristics of related pyrethroid
ccnpounds, resmethrin is believed to be very highly toxic to

Beneficial insects: Reanethrin is highly toxic to honey bees on contact
(LDsO - 0.063 ug/bee).
iaAiiiYprM^1	I
No tolerances have been established for residues of resmethrin in or on
any plant or animal comrodities. A food additive tolerance of 3 ppn (40 CFR
185.5300) has been established for residues of resmethrin in food items
resulting from treatment of food handling establishments and storage areas.
No Codex M*LS have been established for residues of resmethrin in or on
food or feed.
4. Required Unique
All products with mosquito abatement and pest control at aquatic sites
are classified Restricted Use and must contain the following restricted use
classification statement.
Due to acute fish toxicity
For retail sale to and use only by certified
applicators or persons ureter their direct
supervision and only for those uses covered by
the certified Applicator's Certification.
5. Suntnarv of Regulatory Positions
Hie Agency is not placing resmethrin into Special Review. However
because of its high acute toxicity to fish, the Agency has serious
concerns about reanethrin's toxicity to aquatic invertebrate organisns,
particularly in view of the fact that structurally similar pyrethroid
conpounds are highly toxic to these organisms. The JVgency will make a
regulatory decision on this issue after conpleting the review of
outstanding aquatic data. Hie Agency will inpose the restricted use
classification for certain use patterns.
Hie Agency is imposing the restricted use classification for all
products containing resmethrin which bear use directions for mosquito
abatenent and insect control uses at aquatic sites.

Based cm the available toxicity data, the Agency is not requiring the
use of personal protective clothing or reentry intervals.
Because of its structural similarity to otter pyrethroid ccnpounds
which are not known to leach, resnethrin is not expected to contaminate
Hie available residue chemistry data are insufficient to permit the
Agency to conduct a tolerance reassessment.
6- Summary of Maior Data Gaps
Acute Oral
Acute Dermal
Subchronic dermal (21 -Day and 90-Day)
Mutagenicity and Genetic Toxicity (full battery of studies including gene
mutation, chromosome aberration, and other mechanisms of
General metabolism and pharmacokinetics
Residue Chanistrv
Nature of the residue (metabolism)
-	Plants
-	Livestock
Residue analytical methods
Storage stability
Magnitude of residue  Meat/tou Ik/poultry/eggs
Rd handling establishments
Environmental Fate
-	water
Metabolism studies (Lab)
-	aerobic soil
-	anaerobic aquatic
-	aerobic aquatic

-	Leaching and adsorption/desorption
-	Volatility (Lab)
Dissipation (Field)
-	soil
-	aquatic (sediment)
Ecological Effects
Avian and Mannalian Testing
-	Avian Dietary LC50
-	Avian Reproduction
Aquatic Testing
-	Fish early life stage
-	Freshwater fish LC50
-	Acute LC50 freshwater invertebrates
-	Acute LC^o estuarine and marine organisms
-	aquatic invertebrate life cycle
Nantarget Area Phytotoxicity
Tier I
-	Seedling germination/seedling emergence
-	Vegetation vigor
-	Aquatic plant grcvth
Nontarget Insects
- Honeybee: toxicity of residues on foliage

Philip Hutton
Product Manager 17
Insect icide-Rodenticide Branch
Registration Division (TS-767C)
Office of Pesticide Programs
BTvirormental Protection Agency
401 M Street, S. W.
Washington, D. C. 20460
Office location and telephone number:
Room 214, Crystal Mall #2
1921 Jefferson Davis Highway
Arlington, VA 22202
(703) 557-2690
DISCLAIMER: The information in this Pesticide Fact Sheet
is a sunmary only and is not to be used to satisfy data
requirements for pesticide registration and reregistration.
U>e complete Registration Standard for the pesticide may be
obtained from the National Technical Information Service.
Contact the Product Manager listed above for further