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Fact Sheet
Permethrin is a pyrethroid that can be inhaled,
ingested, or absorbed through skin.
Depending on the formulation, permethrin is a non-toxic
to moderately toxic pesticide. Short-term side effects in sensitive
individuals include eye, skin, nose, and throat irritation, and
may include breathing problems. Signs and symptoms of poisoning
following very high exposure include abnormal facial sensation,
dizziness, salivation, headache, fatigue, vomiting, diarrhea,
and irritability to sound and touch. Pulmonary edema, seizures,
and fasciculations may occur in more severe cases. Permethrin
DOES NOT cause cholinesterase inhibition. There are no laboratory
tests to confirm the presence of permethrin in an individual.
Toxicological Effects of permethrin*:
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.
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 [40]. 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. For more
information about permethrin please contact the National Pesticide
Telecommunications Network at 1-800-858-7378 *most studies quoted
were conducted exclusively in animals
This information has been taken directly from the
following sources:
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