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Description

Permethrin, a pyrethroid insecticide, is a chlorinated, synthetic form of pyrethrum, an insecticide derived from chrysanthemum flowers. (Permethrin is longer acting than pyrethrum.) It has multiple uses, including head lice and scabies treatments, insect repellents, household insect foggers and sprays, tick and flea sprays for yards and pets, termite treatments, agricultural and livestock products, mosquito abatement, forestry and treatment of timber.

Though permethrin is often used as the primary active ingredient in consumer products, it may also be combined with more toxic organophosphate or carbamate insecticides. Regardless of the formulation, care should be taken to keep infants from being exposed to permethrin because they may be more sensitive.

Head lice are becoming resistant to permethrin treatments. The alternative, malathion, is not considered by CHEC to be safe for young children.

Health Effects

Immediate Health Effects

If SWALLOWED, permethrin is Moderately Toxic
If ABSORBED THROUGH SKIN, permethrin is Moderately Toxic
If INHALED (SNIFFED OR BREATHED IN), permethrin is Slightly Toxic

Longterm or Delayed Health Effects

Allergen
Neurotoxin = Can harm brain and central nervous system
Suspected Endocrine Disruptor = May interfere with, mimic or block hormones
Asthma Trigger

Other

Skin and eye irritation, skin rashes, inflammation, numbing, tingling, burning sensation.
Allergy-like and respiratory reactions, such as coughing, sneezing, nasal stuffiness, breathing difficulties, pulmonary edema (fluid in the lungs). (More likely among those who are allergic to ragweed and pollens.)
Salivation, headache, dizziness, fatigue, vomiting, diarrhea at high doses.
Nerve damage, seizures, twitching, incoordination, irritability to sound and touch at extremely high doses
Enlargement of liver.
Newborns may be more sensitive than adults to permethrin, based on results from animal studies.

How Exposures Occur

Accidental Ingestion

Children may pick up residues of permethrin from treated surfaces and then ingest them after putting their fingers and hands in their mouths.

Food

Children may consume residues of permethrin found on fruits and vegetables, and in baby food.

Inhalation

Permethrin may drift after it is sprayed both indoors and outdoors. Children and others may accidently breathe fumes containing the pesticide. Permethrin is sometimes used aboard airplanes.

Skin

Children can absorb permethrin from lice shampoos or scabie treatments that are used directly on the skin or scalp. They may also absorb permethrin after touching treated surfaces and pets.

Water

The U.S.Geologic Survey has found permethrin in surface and ground water supplies. However, levels in drinking water have not been reported and are not considered likely.

Significant Statistics

Permethrin accounted for 83% of the risk from pesticide residues in domestically produced canned spinach, as calculated by Consumers Union.

Do You Know What You’re Eating? An Analysis of U.S. Government Data on Pesticide Residues in Foods. Consumers Union, 2000.http://www.consumersunion.org/food/do_you_know2.htm

Solutions

How to detect permethrin

Read labels to determine if permethrin is in products in your home or check PAN’s Pesticide Database for a list of brands and products containing this pesticide. If you hire a professional exterminator, ask for safety information, such as a Material Safety Data Sheet (MSDS), for the products used.
Food: There is no way for parents to determine exactly how much permethrin may be in their children’s food. You can get a rough idea of the fruits and vegetables that may contain permethrin from:

The Environmental Working Group’s Report Card: Pesticides in Produce

Do You Know What You’re Eating? by Consumers Union

Consumers Union’s Update on Pesticides in Children’s Food

How to minimize exposure to permethrin

Avoid Exposure: Ask your neighbors for notification when they spray permethrin and other pesticides outdoors. Bring in pets, laundry, toys, and other outdoor equipment. Cover outdoor tables and ornamental fish ponds. Remain inside while spraying takes place, close windows and doors and turn off your air conditioning (or set it to circulate indoor air) before spraying begins. Keep children inside at least one hour after spraying. Avoid direct contact with surfaces that are still wet from pesticide spraying.
Wash skin and clothing exposed to permethrin with soap and water.

Alternatives

Instead of using insect repellents containing resmethrin, wear protective clothing outdoors, with long sleeves and pant legs. Inspect for ticks after outdoor activities. In regions where Lyme disease and West Nile virus have been identified, use of an insect repellent may be necessary. Insect repellents containing permethrin should only be used on clothing, not skin! Inspect for ticks when returning indoors.
Use a lice comb to remove lice and nits by hand, using a lice comb, rather than relying on pesticide shampoos. This must be done regularly to ensure that all lice and nits are removed.

Shampoos made with enzymes from natural vegetable extracts are a safe and effective alternative to toxic pesticides. The enzymes loosen the “glue” that holds nits in the hair so that they can be combed out.
Choose least-toxic pest control methods, such as Integrated Pest Management, for your home garden, lawn and shrubs. Prevent insects from entry into homes: Repair or install window and door screens; remove standing water outdoors (in roof gutters, old tires, buckets and wading pools) and repair leaky plumbing; seal trash containers.
Buy certified organic foods, which are grown without synthetic pesticides, when you can. See 10 foods to Buy Organic . Otherwise, wash fruits and vegetables well and peel them.

See How To Keep Mosquitos From Biting for more tips on preventing and avoiding mosquito bites.

For More information

Books, articles, factsheets and reports

“Head-lice shampoos can be dangerous,” Consumer Reports (September 2003).

http://www.consumerreports.org/main/detailv3.jsp?CONTENT%3C%3Ecnt_id=325835&FOLDER%3C%3Efolder_id=162687&bmUID=1061401446227

Reduce Your Risk for Tickborne Diseases: How to Apply Permethrin Repellants. Westchester County Government.

http://www.westchestergov.com/health/TickborneHowtoApplyPermethrin.htm

Synthetic Pyrethroids for Mosquito Control. U.S. Environmental Protection Agency, Prevention, Pesticides and Toxic Substances, April 17, 2002.

http://www.epa.gov/pesticides/factsheets/pyrethroids4mosquitos.htm

OVERKILL: Why Pesticide Spraying for West Nile Virus May Cause More Harm Than Good. Toxics Action Center and Maine Environmental Policy Institute, July 2001.

http://www.meepi.org/wnv/mass.htm

How to Use Insect Repellents Safely, U.S. Environmental Protection Agency (April, 2002).

http://www.epa.gov/pesticides/factsheets/insectrp.htm