Malathion General Fact Sheet (2024)

• What is malathion?
• What are some products that contain malathion?
• How does malathion work?
• How might I be exposed to malathion?
• What are some signs and symptoms from a brief exposure to malathion?
• What happens to malathion when it enters the body?
• Is malathion likely to contribute to the development of cancer?
• Has anyone studied non-cancer effects from long-term exposure to malathion?
• Are children more sensitive to malathion than adults?
• What happens to malathion in the environment?
• Can malathion affect birds, fish, and other wildlife?

What is malathion?

Malathion is an insecticide in the chemical family known as organophosphates. Products containing malathion areused outdoors to control a wide variety of insects in agricultural settings and around people's homes. Malathion hasalso been used in public health mosquito control and fruit fly eradication programs. Malathion may also be found insome special shampoos for treating lice. Malathion was first registered for use in the United States in 1956.

What are some products that contain malathion?

Products containing malathion may be liquids, dusts, wettablepowders, or emulsions. There are thousands of products containingmalathion registered for use in the United States.

Always follow label instructions and take steps to avoid exposure. If any exposures occur, be sure to follow the FirstAid instructions on the product label carefully. For additional treatment advice, contact the Poison Control Center at1-800-222-1222. If you wish to discuss a pesticide problem, please call 1-800-858-7378.

How does malathion work?

Malathion kills insects by preventing their nervous system from working properly. When healthy nerves send signalsto each other, a special chemical messenger travels from one nerve to another to continue the message. The nervesignal stops when an enzyme is released into the space between the nerves. Malathion binds to the enzyme andprevents the nerve signal from stopping. This causes the nerves to signal each other without stopping. The constantnerve signals make it so the insects can't move or breathe normally and they die.

People, pets and other animals can be affected the same way as insects if they are exposed to enough malathion.About the same amount of malathion will be taken into the body whether you breathe it in or you swallow it. Malathionis also readily taken into the body through skin, though the amountabsorbed will depend on where the exposure occurs on the body. Malathioncan become more toxic if it has been sitting for a long time, especiallyin a hot place.

How might I be exposed to malathion?

You could be exposed to malathion if you get it on your skin or breathe it in,or if you use a product and eat, drink, or smoke afterwards without washingyour hands. People who apply products containing malathion may be exposedif they do not wear the proper protective equipment. You could alsobe exposed to residues of malathion if you ate food that had been treatedwith this pesticide.

What are some signs and symptoms from a brief exposure to malathion?

People who were exposed to enough malathion to become sick felt nauseatedor vomited, had muscle tremors, cramps, weakness, shortness of breath, a slowedheart rate, headache, abdominal pain and diarrhea.

Pets could be exposed to malathion if they get into a product by accident, or touchor eat plants that have just been sprayed. Pets will be affected by malathion likeother animals. The nervous system is very similar in people and other animals, soanimals poisoned by malathion may show signs similar to those observed in people.

What happens to malathion when it enters the body?

In both humans and animals, malathion travels to the liver and kidneys and affects the nervous system. Generally, thebody can break down malathion and remove it quickly. Studies in rats showed that most malathion was gone fromtheir bodies within a day of exposure.

Is malathion likely to contribute to the development of cancer?

Researchers fed malathion to rats for up to two years and to mice for a year and a half. They found no evidence ofincreased cancer in the treated animals. Other studies using higher doses of malathion in rats and mice found thatthey developed liver cancer. The United States Environmental Protection Agency (U.S. EPA) has determined that thereis "suggestive evidence of carcinogenicity but not sufficient to assess human carcinogenic potential by all routes ofexposure," for malathion.

Has anyone studied non-cancer effects from long-term exposure to malathion?

Rats fed malathion when they were pregnant had lower levels of the target enzyme than other rats. The fetuses alsohad less of the target enzyme. Rabbits were more likely to resorb their fetuses if they were fed malathion when pregnant.Rats that were fed malathion for three weeks had less thyroid activity than other rats.

Are children more sensitive to malathion than adults?

While children may be especially sensitive to pesticides compared to adults, there are currently no data showing that children have increasedsensitivity specifically to malathion.

What happens to malathion in the environment?

Bacteria in the soil may break down malathion and sunlight can break down malathion in the air. Malathion will mixwith water and can move quickly through soil. Because of these properties, malathion can be found in surface waterssuch as streams, and sometimes it is found in well water. The time it takes for malathion to break down to half of theoriginal amount in soil is about 17 days, depending on the soil type. This length of time is known as the half-life. Inwater, malathion has a half-life between 2 and 18 days, depending on conditions like temperature and pH. Malathionvapor may also move long distances in air or fog.

Can malathion affect birds, fish, or other wildlife?

Malathion is highly toxic to bees and other beneficial insects, some fish, andother aquatic life. Malathion is moderately toxic to other fish and birds, andis considered low in toxicity to mammals.