What is permethrin?
• Permethrin is a pyrethroid. It is a synthetic chemical similar to the natural insecticide pyrethrum which comes from the chrysanthemum plant, but it remains effective for longer periods of time.
How does permethrin work?
• Pyrethroids work by quickly paralyzing the nervous system of insects.
• Permethrin kills insects when it contacts them or when they eat it.
• It also has repellent effects.
• It is effective against all stages of insect growth, particularly larvae.
How toxic is permethrin?
• Rats fed high doses of permethrin exhibited tremors,salivation, hyperactivity, hyperexcitability,
• urination, defecation and incoordination.
• In a study involving newborn and adult rats, the newborn rats were found to be more sensitive to
• permethrin than the adults. The enzymes that break down permethrin in the body are not completely developed in the newborn rats. The incomplete development of the liver enzymes made the newborn animals more sensitive to permethrin than mature animals.
What effect does permethrin have on wildlife?
• Permethrin has been found to be highly toxic to fish in laboratory experiments.
• Permethrin is highly toxic to bees in laboratory conditions. However, when used properly, permethrin has a strong repellent effect in the environment and should pose little risk to bees.
• Permethrin is of low toxicity to birds.
Signs of toxicity in humans.
• Permethrin has low to moderate toxicity to humans for short-term exposures.
• Results of animal studies suggest that human newborns may be more sensitive to permethrin than
• Permethrin acts similarly to the insecticide pyrethrum (from the chrysanthemum plant).
• Pyrethrum can cause skin or respiratory reactions in people with hayfever or in people who are sensitive to ragweed and pollen.
• These reactions may include irritation or inflammation of the skin (contact dermatitis) or sneezing, nasal stuffiness, or asthmatic breathing. Although there is no clear evidence that pyrethroids (such as permethrin) cause allergic-type reactions, it is important to recognize this possibility.
• Exposure to permethrin may occasionally produce numbing, tingling, and burning sensations of the
• skin. These sensations are reversible and usually go away within 12 hours.