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Permethrin
A factsheet by the Northwest Coalition for Alternatives to Pesticides (NCAP).
· The insecticide permethrin (in the synthetic pyrethroid family) is widely used on cotton, wheat, corn, alfalfa, and other crops. In addition, over 100 million applications are made annually in and around U.S. homes.
· Permethrin, like all synthetic pyrethroids, is a neurotoxin. Symptoms include tremors, incoordination, elevated body temperature, increased aggressive behavior, and disruption of learning. Laboratory tests suggest that permethrin is more acutely toxic to children than to adults.
· The U.S. Environmental Protection Agency has classified permethrin as a carcinogen because it causes lung tumors in female mice and liver tumors in mice of both sexes. Permethrin inhibits the activity of the immune system in laboratory tests, and also binds to the receptors for a male sex hormone. It causes chromosome aberrations in human and hamster cells.
· Permethrin is toxic to honey bees and other beneficial insects, fish, aquatic insects, crayfish, and shrimp. For many species, concentrations of less than one part per billion are lethal. Permethrin causes deformities and other developmental problems in tadpoles, and reduces the number of oxygen-carrying cells in the blood of birds.
· Permethrin has been found in streams and rivers throughout the United States. It is also routinely found on produce, particularly spinach, tomatoes, celery, lettuce, and peaches.
· A wide variety of insects have developed resistance to permethrin. High levels of resistance have been documented in cockroaches, head lice, and tobacco budworm.
by Caroline Cox
Permethrin is used to kill pest insects in agriculture, home pest control, forestry, and in public health programs, including head lice control. It was first marketed in 1973. Worldwide, the dominant use of permethrin is on cotton, accounting for about 60% (by weight) of the permethrin used. 1 In the U.S., almost 70% of the permethrin used in agriculture is used on corn, wheat, and alfalfa. 2 Over 100 million applications of permethrin are made each year in U.S. homes, and over 18 million applications are made in yards and gardens. 3
Permethrin is a synthetic pyrethroid. Like most members of this family of insecticides, it has four isomers, molecules made up of the same atoms with different three-dimensional structures. 1R,cis-permethrin is the most insecticidally active...