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in 1996. EXTOXNET no longer updates this information, but it may be useful
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E X T O X N E T
A Pesticide Information Project of Cooperative Extension
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EXTOXNET primary files maintained and archived at Oregon State
Revised June 1996
Trade and Other Names:
Trade names include Ammo, Arrivo, Barricade, Basathrin, CCN52,
Cymbush, Cymperator, Cynoff, Cypercopal, Cyperguard 25EC,
Cyperhard Tech, Cyperkill, Cypermar, Demon, Flectron, Fligene CI,
Folcord, Kafil Super, NRDC 149, Polytrin, PP 383, Ripcord,
Siperin, Stockade, and Super.
Many products containing cypermethrin are classified as
Restricted Use Pesticides (RUP) by the EPA because of
cypermethrin's toxicity to fish. Restricted Use Pesticides may be
purchased and used only by certified applicators. Cypermethrin is
classified toxicity class II - moderately toxic. Some
formulations are toxicity class III - slightly toxic. Pesticides
containing cypermethrin bear the Signal Word WARNING or CAUTION
on the product label, depending on the particular formulation.
Cypermethrin is a synthetic pyrethroid insecticide used to
control many pests, including moth pests of cotton, fruit, and
vegetable crops. It is also used for crack, crevice, and spot
treatment to control insect pests in stores, warehouses,
industrial buildings, houses, apartment buildings, greenhouses,
laboratories, and on ships, railcars, buses, trucks, and
aircraft. It may also be used in non-food areas in schools,
nursing homes, hospitals, restaurants, hotels, in food processing
plants, and as a barrier treatment insect repellent for horses.
Technical cypermethrin is a mixture of eight different isomers,
each of which may have its own chemical and biological
properties. Cypermethrin is light stable. It is available as an
emulsifiable concentrate or wettable powder.
cypermethrin is a mixture of eight different isomers, each of
which may have its own chemical and biological properties.
Cypermethrin is light stable. It is available as an emulsifiable
concentrate or wettable powder.
- Acute toxicity: Cypermethrin is a
moderately toxic material by dermal absorption or
ingestion [2,8]. Symptoms of high dermal exposure include
numbness, tingling, itching, burning sensation, loss of
bladder control, incoordination, seizures, and possible
death (2,8). Pyrethroids like cypermethrin may adversely
affect the central nervous system [2,8]. Symptoms of
high-dose ingestion include nausea, prolonged vomiting,
stomach pains, and diarrhea which progresses to
convulsions, unconsciousness, and coma. Cypermethrin is a
slight skin or eye irritant, and may cause allergic skin
reactions . The oral LD50 for cypermethrin in rats is
250 mg/kg (in corn oil) or 4123 mg/kg (in water) [2,8].
EPA reports an oral LD50 of 187 to 326 mg/kg in male rats
and 150 to 500 mg/kg in female rats . The oral LD50
varies from 367 to 2000 mg/kg in female rats, and from 82
to 779 mg/kg in mice, depending on the ratio of
cis/trans- isomers present . This wide variation in
toxicity may reflect different mixtures of isomers in the
materials tested. The dermal LD50 in rats is 1600 mg/kg
and in rabbits is greater than 2000 mg/kg [2,8].
- Chronic toxicity: Not Available
- Reproductive effects: No adverse effects
on reproduction were observed in a three-generation study
with rats given doses of 37.5 mg/kg/day, the highest dose
- Teratogenic effects: Cypermethrin is not
teratogenic . No birth defects were observed in the
offspring of rats given doses as high as 70 mg/kg/day nor
in the offspring of rabbits given doses as high as 30
- Mutagenic effects: Cypermethrin is not
mutagenic, but tests with very high doses on mice caused
a temporary increase in the number of bone marrow cells
with micronuclei. Other tests for mutagenic effects in
human, bacterial, and hamster cell cultures and in live
mice have been negative .
- Carcinogenic effects: EPA has classified
cypermethrin as a possible human carcinogen because
available information is inconclusive. It caused benign
lung tumors in female mice at the highest dose tested
(229 mg/kg/day); however, no tumors occurred in rats
given high doses of up to 75 mg/kg/day .
- Organ toxicity: Pyrethroids like
cypermethrin may cause adverse effects on the central
nervous system. Rats fed high doses (37.5 mg/kg) of the
cis-isomer of cypermethrin for five weeks exhibited
severe motor incoordination, while 20 to 30% of rats fed
85 mg/kg died 4 to 17 days after treatment began .
Long-term feeding studies have shown increased liver and
kidney weights and adverse changes in liver tissues in
test animals . Pathological changes in the cortex of
the thymus, liver, adrenal glands, lungs, and skin were
observed in rabbits repeatedly fed high doses of
- Fate in humans and animals: In humans,
urinary excretion of cypermethrin metabolites was
complete 48 hours after the last of five doses of 1.5
mg/kg/day . Studies in rats have shown that
cypermethrin is rapidly metabolized by hydroxylation and
cleavage, with over 99% being eliminated within hours.
The remaining 1% becomes stored in body fat. This portion
is eliminated slowly, with a half-life of 18 days for the
cis-isomer and 3.4 days for the trans-isomer .
- Effects on birds: Cypermethrin is
practically non-toxic to birds. Its acute oral LD50 in
mallard ducks is greater than 4640 mg/kg . The dietary
LC50 in mallards and bobwhite quail is greater than
20,000 ppm . No adverse reproductive effects occurred
in mallards or bobwhite quail given 50 ppm, the highest
dose tested .
- Effects on aquatic organisms:
Cypermethrin is very highly toxic to fish and aquatic
invertebrates. The LC50 (96-hour) for cypermethrin in
rainbow trout is 0.0082 mg/L, and in bluegill sunfish is
0.0018 mg/L . Its acute LC50 in Daphnia magna, a
small freshwater crustacean, is 0.0002 mg/L .
Cypermethrin is metabolized and eliminated significantly
more slowly by fish than by mammals or birds, which may
explain this compound's higher toxicity in fish compared
to other organisms . The half-lives for elimination
of several pyrethroids by trout are all greater than 48
hours, while elimination half-lives in birds and mammals
range from 6 to 12 hours [20,23]. The bioconcentration
factor for cypermethrin in rainbow trout was 1200 times
the ambient water concentration, indicating that there is
a moderate potential to accumulate in aquatic organisms
. Elimination of half of the accumulated amount of the
compound took nearly eight days. After 14 days 70 to 80%
of the material had been eliminated from the organisms
- Effects on other organisms: Cypermethrin
is highly toxic to bees [8,24].
- Breakdown in soil and groundwater:
Cypermethrin has a moderate persistence in soils. Under
laboratory conditions, cypermethrin degrades more rapidly
on sandy clay and sandy loam soils than on clay soils,
and more rapidly in soils low in organic material . In
aerobic conditions, its soil half-life is 4 days to 8
weeks [8,12,25]. When applied to a sandy soil under
laboratory conditions, its half-life was 2.5 weeks .
Cypermethrin is more persistent under anaerobic
conditions . It photodegrades rapidly with a half-life
of 8 to 16 days. Cypermethrin is also subject to
microbial degradation under aerobic conditions .
Cypermethrin is not soluble in water and has a strong
tendency to adsorb to soil particles. It is therefore
unlikely to cause groundwater contamination .
- Breakdown in water: In neutral or acid
aqueous solution, cypermethrin hydrolyzes slowly, with
hydrolysis being more rapid at pH 9 (basic solution).
Under normal environmental temperatures and pH,
cypermethrin is stable to hydrolysis with a half-life of
greater than 50 days and to photodegradation with a
half-life of greater than 100 days . In pond waters
and in laboratory degradation studies, pyrethroid
concentrations decrease rapidly due to sorption to
sediment, suspended particles and plants. Microbial
degradation and photodegradation also occur [22,27].
- Breakdown in vegetation: When applied to
strawberry plants, 40% of the applied cypermethrin
remained after one day, 12% remained after three days,
and 0.5% remained after seven days, with a light rain
occurring on day 3 . When cypermethrin was applied to
wheat, residues on the wheat were 4 ppm immediately after
spraying and declined to 0.2 ppm 27 days later. No
cypermethrin was detected in the grain. Similar residue
loss patterns have been observed on treated lettuce and
celery crops .
- Appearance: Pure isomers of cypermethrin
form colorless crystals. When mixed isomers are present,
cypermethrin is a viscous semi-solid or a viscous, yellow
- Chemical Name:
- CAS Number: 52315-07-8
- Molecular Weight: 416.30
- Water Solubility: 0.01 mg/L @ 20 C;
insoluble in water 
- Solubility in Other Solvents: methanol
v.s.; acetone v.s.; xylene v.s. 
- Melting Point: 60-80 C (pure isomers)
- Vapor Pressure: 5.1 x 10-7 nPa @ 70 C
- Partition Coefficient: 6.6020 
- Adsorption Coefficient: 100,000 
- ADI: 0.05 mg/kg/day 
- MCL: Not Available
- RfD: 0.01 mg/kg/day 
- PEL: Not Available
- HA: Not Available
- TLV: Not Available
Zeneca Ag Products
1800 Concord Pike
Wilmington, DE 19897
- Phone: 800-759-4500
- Emergency: 800-759-2500
References for the information in this PIP can be found in
Reference List Number 2
information in this profile does not in any way replace or
supersede the information on the pesticide product labeling or
other regulatory requirements. Please refer to the pesticide