Permethrin
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Molecular Formula: C21H20Cl2O3
Skeletal Sketch: 
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BACKGROUND
The US EPA puts out RED reports that show the history and toxicity of different chemicals. The EPA concluded that permethrin was highly toxic to aquatic life and was classified as a Restricted Use Pecticide (RUP) and approved for cotton use. From 1982 to 1989 it was classified and approved for use on another 55+ crops as a RUP.
Permethrin is a synthetic chemical that is the artificial analog of naturally occurring pyrethrin from flowers. It is widely used as an insectiside and acaricide[EXPLAIN WHAT AN ACARACIDE IS]. It was first used as an insectiside on cotton plants in the 1970s and is now a common chemical in insect repellants. In agriculture it is mainly used on cotton, wheat, maize, and alfalfa crops. In Europe it is also used on trees against wood boring beatles. It is also used to kill pests on chickens as well as ants, termites, head lice, and pests responsible for scabies. Permethrin is a neurotoxicant that kills indiscriminately and can easily kill insects that are not the intended target such as honey bees, aquatic life, and small mamals.
Permethrin is also used in combating tick populations everywhere, but is used more in Connecticut because of the large tick population and the problems associated with it. Some dog collars that kill ticks contain permethrin. Problems have been caused when pet owners use these dog collars on cats. Permethrin is very toxic to cats and the tick collars or formulas very often kill them. In rats Permethrin has caused cancerous cells in the liver. In general, Permethrin has not been identified as being deadly to most mammals. It is, however, very deadly to aquatic life. This is mostly because fish lack an enzyme to break down permethrin.
Clothing applications of permethrin were developed by Coulston Products Incorporated, in cooperation with and for the U. S. Military.
HEALTH and ENVIRONMENTAL ISSUES
The Connecticut Department of Public Health says that Permethrin "is poorly absorbed through the skin and is rapidly inactivated by the body. Skin reactions have been uncommon." In human tissue samples it has caused the growth of tumors in nasal passage tissue samples and lung tissue samples. These studies have led the US EPA to clasify Permethrin as a Category C Carcinogen: Possible human carcinogen. The results of these studies are preliminary. In humans, Permethrin is more toxic when ingested orally and is less toxic when exposure is through the skin. If you take nothing else away from this paragraph, take this: dont eat permethrin.
Unfortunately, not eating permethrin is not be as simple or straight foreward as it sounds. It is often found on produce that is sprayed with it. Spinach, tomatoes, celery, lettuce, peaches, tobacco, and cotton have all been documented with leftover permethrin on them. The Environmental Working Group found permethrin in peach baby food (44 percent of the samples tested). In 1996 Permethrin was the 10th most detected pesticide in food so not eating it requires a level of awareness and care. There is residue of this pesticide on a lot of food. That being said, the concentrations on food are very small and are not likely to harm humans.
In areas where there is an elevated level of permethrin use, it has been found in the water. It has been found in rivers in Mississippi, Washington, Idaho, the Georgia-Florida Coastal plain, California, and Arkansas. It has also been found in groundwater in Virginia which presents a problem that so far has not been addressed. If permethrin is found in groundwater then it can travel into underground water systems and persists long enough and in large enough quantities to be detected there.
This report claims that:"
Based on tests with laboratory animals, it appears children may be more sensitive to permethrin than adults. Permethrin is almost 5 times more acutely toxic to 8-day-old rats than it is to adult rats."
In agricultural soil, permethrin has a half life of 17 to 43 days depending on the region. One study attached ear tags covered with permethrin to cows and then tested various things around the pasture for permethrin. The pecticide was found on every surface analyzed; the cows, fence polls, grass, and tree bark. Some residue was found three months after the tags were applied. This shows a much longer persistence than previously thought.
A final health concern in the use of Permethrin is the number of "inert ingredients" that are put into the pecticide. These inert ingredients are claimed as trade secrets by pecticide manufacturers. This insecticide fact sheet on Permethrin says the following ingredients are in pecticides alongside Permethrin and claims the following ill effects:
Xylenes are in the agricultural insecticides and can cause eye and skin irritation, headaches, nausea, confusion, tremors, and anxiety in exposed humans.
Methyl paraben is in the head lice cream rinse Nix which is regulated as a drug not as a pesticide. Methyl paraben is a skin sensitizer, and causes eye, skin, digestive, and respiratory irritation.
Dimethyl ether is in some household insecticides. It causes respiratory, skin, and eye irritation and depresses the cen-tral nervous system. It is also a severe fire hazard.
Butane is in some household insecticides. Short-term exposure causes irritation, nausea, drowsiness, convulsions, and coma.
More info on these can be found here.
SOURCES
"Permethrin." Wikipedia. 2008. 4 Mar 2008 <http://en.wikipedia.org/wiki/Permethrin>.
Cox, Caroline. "Permethrin." Journal of Pecticide Reform 18(1998)
"Permethrin". 5 Mar, 2008 <http://www.permethrin-repellent.com/>.
"Permethrin Facts". US EPA. 6 Mar, 2008 <http://www.epa.gov/oppsrrd1/REDs/factsheets/permethrin_fs.htm>.
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