E X T O X N E T
Pesticide Information Profiles
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 Assessment Program.
EXTOXNET primary files maintained and archived at Oregon State University
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.
Status: 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.
Chemical Class: pyrethroid
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.
Formulation: Permethrin 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 circumstances.
- 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 inconclusive.
- 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 quail .
- 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
- 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
DISCLAIMER: The 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 product labeling.