The information in this profile may be out-of-date. It was last revised
in 1996. EXTOXNET no longer updates this information, but it may be useful
as a reference or resource.
Please visit the National Pesticide Information Center (NPIC) to find
updated pesticide fact sheets.
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E X T O X N E T
A Pesticide Information Project of Cooperative Extension
Offices of Cornell University, Oregon State University, the
University of Idaho, and the University of California at Davis
and the Institute for Environmental Toxicology, Michigan State
University. Major support and funding was provided by the
USDA/Extension Service/National Agricultural Pesticide Impact
EXTOXNET primary files maintained and archived at Oregon State
Revised June 1996
Trade and Other Names:
Trade names include Ambush, BW-21-Z, Cellutec, Dragnet, Ectiban,
Eksmin, Exmin, FMC 33297, Indothrin, Kafil, Kestrel, NRDC 143,
Pounce, PP 557, Pramex, Qamlin, and Torpedo.
Permethrin is a moderately to practically non-toxic pesticide in
EPA toxicity class II or III, depending on the formulation.
Formulations are placed in class II due to their potential to
cause eye and skin irritation. Products containing permethrin
must bear the Signal Word WARNING or CAUTION, depending on the
toxicity of the particular formulation. All products for
agricultural uses (except livestock and premises uses) are
Restricted Use Pesticides (RUPs) because of their possible
adverse effects on aquatic organisms. Restricted Use Pesticides
may be purchased and used only by certified applicators.
Permethrin is a broad spectrum synthetic pyrethroid insecticide,
used against a variety of pests, on nut, fruit, vegetable,
cotton, ornamental, mushroom, potato, and cereal crops. It is
used in greenhouses, home gardens, and for termite control. It
also controls animal ectoparasites, biting flies, and
cockroaches. It may cause a mite buildup by reducing mite
predator populations. Permethrin is available in dusts,
emulsifiable concentrates, smokes, ULV (ultra-low volume), and
wettable powder formulations.
is available in dusts, emulsifiable concentrates, smokes, ULV
(ultra-low volume), and wettable powder formulations.
- Acute toxicity: Permethrin is moderately
to practically non-toxic via the oral route, with a
reported LD50 for technical permethrin in rats of 430 to
4000 mg/kg . Via the dermal route, it is slightly
toxic, with a reported dermal LD50 in rats of over 4000
mg/kg, and in rabbits of greater 2000 mg/kg [12,2].
Permethrin caused mild irritation of both the intact and
abraded skin of rabbits. It also caused conjunctivitis
when it was applied to the eyes . The 4-hour
inhalation LC50 for rats was greater than 23.5 mg/L,
indicating practically no inhalation toxicity. The
toxicity of permethrin is dependent on the ratio of the
isomers present; the cis-isomer being more toxic .
- Chronic toxicity: No adverse effects
were observed in dogs fed permethrin at doses of 5
mg/kg/day for 90 days . Rats fed 150 mg/kg/day for 6
months showed a slight increase in liver weights .
Very low levels of permethrin in the diet of chickens
(0.1 ppm for 3 to 6 weeks after hatching) have been
reported to suppress immune system activity .
- Reproductive effects: The fertility of
female rats was affected when they received very high
oral doses of 250 mg/kg/day of permethrin during the 6th
to 15th day of pregnancy . It is not likely that
reproductive effects will be seen in humans under normal
- Teratogenic effects: Permethrin is
reported to show no teratogenic activity .
- Mutagenic effects: Permethrin is
reported to show no mutagenic activity .
- Carcinogenic effects: The evidence
regarding the carcinogenicity of permethrin is
- Organ toxicity: Permethrin is suspected
of causing liver enlargement of the liver and nerve
damage . Effects on the immune system have been noted
in animal studies.
- Fate in humans and animals: Permethrin
is efficiently metabolized by mammalian livers .
Breakdown products, or "metabolites," of
permethrin are quickly excreted and do not persist
significantly in body tissues . When permethrin is
administered orally to rats, it is rapidly metabolized
and almost completely eliminated from the body in a few
days. Only 3 to 6% of the original dose was excreted
unchanged in the feces of experimental animals .
Permethrin may persist in fatty tissues, with half-lives
of 4 to 5 days in brain and body fat . Permethrin does
not block, or inhibit, cholinesterase enzymes .
- Effects on birds: Permethrin is
practically non-toxic to birds . The oral LD50 for
the permethrin formulation, Pramex, is greater than 9900
mg/kg in mallard ducks, greater than 13,500 mg/kg in
pheasants, and greater than 15,500 mg/kg in Japanese
- Effects on aquatic organisms: Aquatic
ecosystems are particularly vulnerable to the impact of
permethrin. A fragile balance exists between the quality
and quantity of insects and other invertebrates that
serve as fish food . The 48-hour LC50 for rainbow
trout is 0.0125 mg/L for 24 hours, and 0.0054 mg/L for 48
hours . The 48-hour LC50 in bluegill sunfish and
salmon is 0.0018 mg/L . As a group, synthetic
pyrethroids were toxic to all estuarine species tested.
They had a 96-hour LC50 of less than or equal to 0.0078
mg/L for these species . The bioconcentration factor
for permethrin in bluefish is 715 times the
concentrations in water and is 703 in catfish. This
indicates that the compound has a low to moderate
potential to accumulate in these organisms.
- Effects on other organisms: Permethrin
is extremely toxic to bees. Severe losses may be expected
if bees are present at treatment time, or within a day
thereafter [2,43]. Permethrin is also toxic to wildlife
. It should not be applied, or allowed to drift, to
crops or weeds in which active foraging takes place .
- Breakdown in soil and groundwater:
Permethrin is of low to moderate persistence in the soil
environment, with reported half-lives of 30 to 38 days
[12,25]. Permethrin is readily broken down, or degraded,
in most soils except organic types. Soil microorganisms
play a large role in the degradation of permethrin in the
soil. The addition of nutrients to soil may increase the
degradation of permethrin. It has been observed that the
availability of sodium and phosphorous decreases when
permethrin is added to the soil . Permethrin is
tightly bound by soils, especially by organic matter.
Very little leaching of permethrin has been reported
. It is not very mobile in a wide range of soil types
. Because permethrin binds very strongly to soil
particles and is nearly insoluble in water, it is not
expected to leach or to contaminate groundwater.
- Breakdown in water: The results of one
study near estuarine areas showed that permethrin had a
half-life of less than 2.5 days. When exposed to
sunlight, the half-life was 4.6 days . Permethrin
degrades rapidly in water, although it can persist in
sediments [15,45]. There was a gradual loss of toxicity
after permethrin aged for 48 hours in sunlight at 0.05
mg/L in water .
- Breakdown in vegetation: Permethrin is
not phytotoxic, or poisonous, to most plants when it is
used as directed. Some injury has occurred on certain
ornamental plants. No incompatibility has been observed
with permethrin on cultivated plants. Treated apples,
grapes, and cereal grains contain less than one mg/kg of
permethrin at harvest time .
- Appearance: Permethrin is an odorless,
colorless crystalline solid or a viscous liquid that is
pale brown .
- Chemical Name:
- CAS Number: 52645-53-1
- Molecular Weight: 391.30
- Water Solubility: ca. 0.2 mg/L @ 20 C
, insoluble in water
- Solubility in Other Solvents: s. in most
organic solvents except ethylene glycol 
- Melting Point: 34-35 C 
- Vapor Pressure: 0.045 mPa @ 25 C 
- Partition Coefficient: 6.1004
- Adsorption Coefficient: 100,000 
- ADI: 0.05 mg/kg/day 
- MCL: Not Available
- RfD: 0.05 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