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Malathion Also Known As: malathion


An organophosphate insecticide used on home and public lawns, gardens, trees and shrubs, as well as on cotton and some food crops. Malathion is also sprayed, aerially, over cities, suburbs and farmland to control mosquitoes and Mediterranean fruit flies. Some head lice treatments may also contain malathion.

Health Effects

Immediate Health Effects
  • If SWALLOWED, malathion is Moderately Toxic
  • If ABSORBED THROUGH SKIN, malathion is Not Available
  • If INHALED (SNIFFED OR BREATHED IN), malathion is Slightly Toxic
Longterm or Delayed Health Effects
  • This chemical is considered an Unclassifiable Carcinogen by the World Health Organization, the U.S. Environmental Protection Agency, or another agency.
  • Neurotoxin = Can harm brain and central nervous system
  • Suspected Endocrine Disruptor = May interfere with, mimic or block hormones
  • Asthma Trigger
  • Can affect the brain and nervous system.
  • Immediate effects may include nausea, dizziness, numbness, tingling sensations, pinpoint pupils, incoordination, headache, tremor, nausea, abdominal cramps, sweating, teary eyes, salivation, blurred vision, slow heartbeat, confusion.
  • At very high exposures, can cause respiratory paralysis and death.
  • Can cause skin rashes or irritation (redness, itchy or burning), hives or eye irritation (redness, tearing, swelling, blurred vision).
  • There is some evidence that malathion can cause cancer, based upon animal studies. See �Other� section for details.
  • Inorganic mercury can be corrosive and causes burns to skin, eyes, and respiratory passages.

How Exposures Occur

Absorption through the skin
  • Children can be exposed by touching recently treated garden vegetables and fruits.  Surfaces in homes, on playground equipment, recently treated lawns are other sources.  Lawns and outdoor surfaces down-wind of farms that have sprayed malathion may also contain harmful residues. Lawns and outdoor surfaces may become contaminated when malathion is applied aerially.  The U.S. EPA considers that there is a concern for toddlers who may be exposed after application to lawns or other turf areas.

    Lice shampoos containing malathion can be absorbed through the scalp.
In Food
  • Children may ingest traces of malathion in foods that have been treated with it. Malathion residues have been found on samples of bell peppers, celery, cherries, grapes, nectarines, peaches, pears, raspberries, spinach, and strawberries, among other foods.
  • Children may breathe in malathion while it is being applied to nearby lawns, gardens or farms, or aerially for med-fly or mosquitoes.
  • Children may accidently eat malathion by putting grass or soil into their mouths, or by touching contaminated surfaces and putting fingers in their mouths.

Significant Statistics

Nearly 17 million pounds of malathion are applied annually in the U.S., primarily to control boll weevils on cotton.

Overview of Malathion Risk Assessment. U.S. Environmental Protection Agency Office of Pesticide Programs, November 6, 2000.

10,637 cases of malathion-related illness reported to Poison Control Centers between 1985 and 1992.

Review of Malathion Incident Reports. U.S. Environmental Protection Agency Office of Prevention, Pesticides, and Toxic Substances, August 18, 1998.

After malathion was sprayed aerially in several counties in Florida in 1998 to control the Mediterranean fruit fly, 123 people reported illness that was considered probably or possibly related to the spraying. 

�Surveillance for Acute Pesticide-Related Illness During the Medfly Eradication Program Florida, 1998,� Journal of the American Medical Association Morbidity and Mortality Weekly Report, Vol. 282, No. 23 (December 15, 1999).


How to detect malathion

  • There are over 250 products containing malathion on the market. Read labels to determine if the pesticide products and lice shampoos in your home are among them. 

    You can also find out if malathion is an ingredient in a pesticide product or lice shampoo on Pesticide Action Network Pesticides Database.
  • If your district resorts to aerial or ground spraying near your home for mosquito or other pest control, contact your local health department to find out which chemicals are being used.
  • Food: There is no way for parents to determine exactly how much malathion may be in their children’s food. You can get a rough idea of the fruits and vegetables that may contain malathion 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 malathion

  • Avoid the use of pesticides whenever possible, especially near children.  If you do have pesticides in your home, keep them tightly closed and out of the reach of children.
  • Contact your local sanitation department or hazardous waste disposal program to find out how to dispose of pesticides properly. 
  • Earth 911 lists hazardous waste disposal sites by zip code.
  • Prevent your home and lawn from becoming a breeding ground for mosquitoes. Unclog roof gutters, and remove all sources of standing water, such as old tires, bird baths, wading pools, and flowerpots.

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


For More information

Books, articles, factsheets and reports

Chemical Watch Factsheet: Malathion. Beyond Pesticides/National Coalition Against the Misuse of Pesticides.

Brenner, Loretta. �Malathion,� Journal of Pesticide Reform, Vol. 12, No. 4 (Winter 1992).

Head Lice Information. Harvard School of Public Health, Updated August 9, 2000.

Rumsey, Kay. "Dealing with Head Lice," Journal of Pesticide Reform, Vol. 18, No. 2 (Summer 1998).

Olkowski, William, Sheila Daar, and Helga Olkowski. Common-Sense Pest Control: Least Toxic Solutions for Your Home, Garden, Pets, and Community. Newton, Conn,: Taunton Press, 1991.

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

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

Other government agencies

National Pesticide Information Center

Oregon State University
333 Weniger Hall
Corvallis, OR 97331-6502

U.S. Environmental Protection Agency

Office of Pesticide Programs
Ariel Rios Building
1200 Pennsylvania Ave. NW
Washington DC 20460

Nonprofit organizations

Beyond Pesticides/National Coalition Against the Misuse of Pesticides (NCAMP)

701 E Street SE, Suite 200
Washington, DC 20003

Northwest Coalition for Alternatives to Pesticides (NCAP)

P.O. Box 1393
Eugene, OR 97440

Pesticide Action Network North America (PANNA)

49 Powell Street, Suite 500
San Francisco, CA 94102

The National Pediculosis Association

P.O. Box 610189
Newton, MA 02461

Other websites

Pesticide Action Network Pesticide Database

Malathion Medical Research Index

Pesticide Action Network Pesticide Advisor


The cancer-causing potential of malathion has been debated among U.S. EPA staff and other scientists. In EPA�s original February 2000 risk assessment of malathion, the agency classified malathion as a �likely human carcinogen.� This status was changed in April 2000, when EPA downgraded malathion to �suggestive evidence of carcinogenicity but not sufficient to assess human carcinogenic potential.� This lesser regulatory status results in fewer restrictions on the pesticide�s use.

Several dissenting EPA scientists and scientific advisors believe that the downgrade of this classification by EPA was in response to industry pressure. In order to achieve a lower status, it is alleged that test data was manipulated to reflect a lower incidence of cancer in animals exposed to malathion. The changed decision did not reflect any new data.

Letter from EPA Senior Toxicologist Dr. Brian Dementi Concerning Cancer and Non-Cancer Toxicology Issues. U.S. Environmental Protection Agency, November 8, 2000.

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