Paraquat

Background

Paraquat is a toxic chemical that is commonly used as an herbicide (plant killer), usually for weed and grass control.

In the United States, paraquat is usually available as a liquid with different levels of strength. The US Environmental Protection Agency classifies paraquat as "restricted use."1 This means that it can be used only by people who have licenses.

Because paraquat is highly poisonous, the United States requires the following safety measures:

• Blue dye is added to keep it from being confused with other beverages.
• A sharp smell acts as a warning.
• A vomiting agent is added in case it is swallowed.

Paraquat from outside the United States may not have these protections added.

Where it is found

Paraquat was first produced for commercial purposes in 1961. Worldwide, paraquat is still one of the most commonly used herbicides (plant killers).

In the United States, due to its harmfulness, paraquat is only available for use by commercially licensed users.

How it works

Paraquat causes direct damage when it comes into contact with the lining of the mouth, stomach, or intestines.

After paraquat enters the body, it spreads to all areas of the body. Paraquat causes toxic chemical reactions to occur throughout many parts of the body, mostly the lungs, liver, and kidneys. Cells pick and choose how they let paraquat into the cells. This is likely because of "active transport," the moving of stuff in and out of the cell.

Signs and symptoms

The level of paraquat poisoning depends on the amount, how someone was exposed, and how long they were exposed. It also depends on the person's health condition when they were exposed.

Showing these signs and symptoms does not necessarily mean that a person has been exposed to paraquat.

Swallowing small to medium amounts of paraquat may lead to these signs and symptoms within several days to several weeks:

• Heart failure
• Kidney failure
• Liver failure
• Lung scarring

Swallowing large amounts of paraquat leads to the following signs/symptoms within a few hours to a few days:

• Acute kidney failure
• Confusion
• Coma
• Fast heart rate
• Injury to the heart
• Liver failure
• Lung scarring (happens more quickly the more you swallow)
• Muscle weakness
• Pulmonary edema (fluid in the lungs)
• Respiratory (breathing) failure, possibly leading to death
• Seizures

After a person swallows a large amount of paraquat, the following may occur:

• Sweling and pain in the mouth and throad
• Nausea
• Vomiting
• Abdominal pain
• Diarrhea (possibly bloody)

If these gastrointestinal symptoms are severe, it may cause the following:

• Dehydration (not enough fluids in the body)
• Electrolyte abnormalities (not enough sodium and potassium in the body)
• Low blood pressure

Exposure

People with licenses to use paraquat are the most at risk for exposure.

Paraquat is not known to have been used in any terrorist attacks or wars.

Ingestion (swallowing)

The most likely way to be poisoned by paraquat is ingestion (swallowing). Paraquat can be mixed easily with food, water, or other beverages. Eating or drinking food or beverages with paraquat could poison people.

Protections include the blue dye, odor (smell), and vomiting agent. If the paraquat does not have protections, people might not know that the food, water, or other beverages are unsafe.

Skin exposure

Paraquat poisoning is also possible after skin exposure. Poisoning is more likely if skin exposure lasts for a long time or a strong version of paraquat is used. Poisoning is also more likely to happen if paraquat touches skin that has sores, cuts, or a severe rash.

Inhaled (breathed in)

If it is breathed in, paraquat could cause poisoning that causes lung damage. In the past, some marijuana in the United States has been found to have paraquat.

What to do if you are exposed

Most people are exposed by swallowing paraquat. Do not swallow more paraquat if you think you are poisoned.

Actions you can take before going to the hospital may include swallowing activated charcoal or Fuller's earth. This will stick to the swallowed paraquat.

If you think you were exposed to liquid paraquat, do the following.

Take off your clothes

Take off the clothing as quickly as possible. Cut clothes off instead of pulling it over the head. If you are helping others, avoid touching unsafe areas and take off the clothes quickly.

Wash your body

As quickly as possible, wash any liquid paraquat from your skin with lots of soap and water.

If your eyes are burning or your vision is blurred, rinse your eyes with plain water for 10 to 15 minutes.

If you wear contacts, remove them and put them with the dirty clothing. Do not put the contacts back in your eyes (even if they are not disposable contacts).

If you wear eyeglasses, wash them with soap and water. You can put your eyeglasses back on after you wash them.

Throw your clothes away

After you have washed yourself, place your clothing inside a plastic bag. Avoid touching unsafe areas of the clothing. If you can't avoid touching unsafe areas, or you aren't sure where they are, wear rubber gloves. You can also use tongs, tool handles, sticks, or similar objects.

Anything that touches the dirty clothing should also be placed in the bag. If you wear contacts, put them in the plastic bag, too.

Tie the bag, and then put that bag inside another plastic bag. Throwing away your clothes this way helps protect you and others from any chemicals that might be on your clothes.

When the local or state health department or emergency team arrive, tell them what you did with your clothes. The health department or emergency team will arrange for further disposal. Do not handle the plastic bags yourself.

Treatment

Treatment starts with removing the paraquat from the body (decontamination). If paraquat is swallowed, activated charcoal or Fuller's earth are used to prevent the body from absorbing (taking in) more paraquat.

Nasogastric suction (emptying the stomach using a tube through the nose) may be used for paraquat swallowed within 1 hour.

Supportive care measures should be provided. Supportive care measures include:

• Intravenous fluids (fluids given through a needle inserted directly into a vein)
• Medications to help with breathing
• Medications to raise low blood pressure
• Ventilator to support breathing
• Possibly treatment for kidney failure (this is called dialysis)

Too much oxygen should not be given because it may make paraquat poisoning worse. No proven antidote or cure exists for paraquat poisoning.

Long-term health effects

Long-term health effects include:

• Lung damage (scarring
• Kidney failure
• Heart failure
• Scarring in the esophagus (tube from the mouth to the stomach)
  • Difficulty swallowing

People who swallowed large amounts of paraquat are not likely to survive.

More information

People can contact one of the following:

• Regional poison control center: 1-800-222-1222
• Centers for Disease Control and Prevention Public Response Hotline
  • Phone: 800-CDC-INFO
  • Teletypewriter (TTY): 888-232-6348
  • E-mail inquiries: cdcinfo@cdc.gov
• National Institute for Occupational Safety and Health (NIOSH)
• Pocket Guide to Chemical Hazards.