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Back To Vidyya Pesticides & Mosquito Control

Advice From The EPA

Mosquito-borne diseases affect millions of people worldwide each year. In the US alone there are over 150 species of mosquitoes. These mosquitos transmit diseases such as encephalitis, dengue fever and malaria. To combat mosquitoes and the potential public health hazards they present, many countries have established mosquito control programs. These programs can include ground and aerial application of pesticides along with non-chemical forms of control and prevention.

It is the priority of the Environmental Protection Agency (EPA) to protect human health and the environment and provide support to states dealing with serious outbreaks of infectious diseases from mosquitoes. EPA helps to ensure that states and localities apply pesticides according to proper application methods to reduce human exposure.

The following questions and answers provide additional information on safety precautions, and information on insecticides used for mosquito control programs.

How does EPA ensure the safest possible use of pesticides?

It is a priority of EPA to protect human health and the environment from the adverse effects of pesticides. EPA must evaluate and register pesticides before they may be used, sold or distributed in the United States. To evaluate a pesticide registration application, EPA assesses a wide variety of potential human health and environmental effects associated with use of the product. The producer of the pesticide must provide data from tests done according to EPA guidelines. These tests must determine whether a pesticide has the potential to cause adverse effects on humans, wildlife, fish and plants, including endangered species and non-target organisms, as well as possible contamination of surface water or groundwater from leaching, runoff and spray drift. If a pesticide meets EPA requirements that ensure no harm to human health and the environment, the pesticide is approved for use in strict accordance with label directions.

The EPA is working to ensure that the Food Quality Protection Act of 1996 (FQPA) is properly implemented to achieve high standards of protection, especially for children, while preserving the strength of agricultural communities and maintaining viable pest control products.

It must be noted however, that no pesticide is 100 percent safe and care must be exercised in the use of any pesticide.


What EPA-approved insecticides are used by countries most frequently?

Malathion is an insecticide used for mosquito control. EPA requires that Malathion be applied at very low rates by sprayers operated by state or local applicators from trucks or aircraft to ensure protection of public health and the environment. Malathion kills mosquitoes when they contact spray particles in the air. mosquitoes, unlike humans, lack the enzymes that quickly break down Malathion. Thus, Malathion can be applied at low concentrations with little risk to humans.

Naled is an insecticide that is registered primarily for use on land to kill adult mosquitoes and blackflies. Naled is also used on some food and feed crops to control pests, and in pet flea collars. Most use of Naled for mosquito control occurs in the southern states, particularly Florida and other Gulf states. When applied at low concentrations as required by the label, Naled should pose little risk to humans from mosquito control use. There is potential for acute and some potential for chronic risks to freshwater invertebrates from the use of Naled. Naled breaks down rapidly in soil and water.

Malathion and Naled are part of a group of pesticides known as organophosphates. All organophosphate pesticides are currently under new review by EPA to ensure greater safety. The EPA made public a comprehensive risk assessment of Malathion and Naled on 12 May 2000. This review is available for public comment until the end of July 2000.

Sumithrin is an insecticide registered for use against mosquitoes in swamps, marshes and recreational areas. It imitates natural pesticides found in chrysanthemums, and is the active ingredient in the product Anvil 10 + 10. Sumithrin can also be used to kill pests in transport vehicles such as aircraft, ships, railroad cars and truck trailers, and for institutional non-food use, use in homes and gardens, greenhouses and on pets. Sumithrin breaks down rapidly in the environment and is expected to pose little risk to humans when used at low concentrations for mosquito control.

Resmethrin is an insecticide used to control flying and crawling insects in the home, lawn, garden and at industrial sites. Resmethrin is the active ingredient in the product Scourge, which is used to control adult mosquitoes. It also imitates natural pesticides found in chrysanthemums. It is only registered for outdoor use and is generally applied in very small amounts.

Resmethrin decomposes quickly in sunlight or when exposed to air. Resmethrin products have low toxicity to humans, but are very toxic to fish. Resmethrin products for mosquito control at or near aquatic sites are classified as Restricted Use Pesticides and may only be used by specially trained and licensed applicators.

Bacillus sphaericus and Bacillus thuringiensis israelensis are biological pesticides used for mosquito larvae control in water. When the larvae eat them, the pesticides release a protein that disrupts the feeding process of the mosquito larvae causing them to starve and die.Bacillus sphaericus and Bacillus thuringiensis israelensis are a naturally occurring bacteria found throughout the world and are of limited toxicity to humans.


What should be done to reduce exposure to pesticides during mosquito control spraying?

There are a number of common sense steps recommended by EPA to help reduce possible exposure to pesticides during spraying:

  • Look for notices about spraying in the newspapers and stay tuned to radio and TV for announcements. 

  • Whenever possible, remain indoors with windows closed and air conditioning turned off when spraying is taking place.

  • If you have to remain outdoors, avoid eye contact with the spray. If you get pesticide spray in your eyes, immediately rinse them with water or eye drops. 

  • Your child’s health should not be affected by the low levels of pesticides used in mosquito control. However, bring laundry and toys indoors before spraying begins and wash with soap and water if exposed to pesticides during spraying.

  • Bring your pets indoors, and cover ornamental fish ponds to avoid direct exposure.

  • Cover outdoor tables and play equipment or rinse them off with water after spraying is finished.

  • Cover swimming pool surfaces when it is feasible (but given the small concentrations of pesticides used, special precautions or waiting periods are not usually necessary for outdoor swimming pools).

  • Wash exposed skin surfaces with soap and water if you come in contact with  pesticides.

  • Wash any exposed fruits and vegetables, such as homegrown or purchased from an outside vendor, with water before storing, cooking or eating them.

  • There is no need to relocate during spraying, but consult your physician if you have serious physical or psychological concerns regarding the spraying.

  • If you think pesticides are making you sick, call the National Pesticide Telecommunications Network at 1-800-858-7378.

    What can be done to control mosquitoes?

    • Homeowners should get rid of any standing water around the home, including water in potted plant containers, garbage cans and gutters and drains. Mosquitoes will develop in any puddle that lasts more than four days.

    • Make sure window and door screens are "bug tight."Replace outdoor lights with yellow "bug" lights.

    • Wear head nets, long sleeve shirts, and long pants if venturing into areas with high mosquito populations, such as salt marshes or wooded areas. Use mosquito repellants when necessary.

      For information about the health effects of pesticides used in mosquito control or other pesticides, contact the National Pesticide Telecommunications Network (NPTN):

      • Toll-free hotline: 1-800-858-7378. Standard hours are 9:30 a.m. to 7:30 p.m. Eastern time, every day except holidays. Callers outside normal hours can leave a voice mail message, and NPTN will return these calls the next business day.

        For more information on EPA's program to regulate pesticides, visit:

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Editor: Susan K. Boyer, RN
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