Description

Warfarin is a rodenticide used in the home, outdoors, in food service establishments, near fruit trees, in storage buildings, sewers and other places where rodents may be a problem. This white, odorless, tasteless compound, an anti-coagulant, causes bleeding and blood-thinning.

Children may come into contact with warfarin in its powder, pellet or bait forms. It should never be used anywhere near children!

Warfarin is also used for medical purposes.

Health Effects

Immediate Health Effects

If SWALLOWED, 3-(alpha-acetonylbenzyl)-4- hydroxycoumarin (warfarin) is Very Highly Toxic
If ABSORBED THROUGH SKIN, 3-(alpha-acetonylbenzyl)-4- hydroxycoumarin (warfarin) is Very Highly Toxic (this is not common and occurs only under extraordinary circumstances)
If INHALED (SNIFFED OR BREATHED IN), 3-(alpha-acetonylbenzyl)-4- hydroxycoumarin (warfarin) is Very Highly Toxic

Longterm or Delayed Health Effects

This chemical may cause cancer. It is considered a Possible Carcinogen by the World Health Organization, the U.S. Environmental Protection Agency, or another agency.
Neurotoxin = Can harm brain and central nervous system
Development Toxicant = Can interfere with normal development of a fetus or child

Other

Multiple birth defects including bone and nasal deformities, blindness or unusually small eyes, hydrocephalus (water on the brain), mental retardation, and fatal fetal hemorrhaging.
Fetal, neonatal or maternal bleeding.
Bleeding from the nose, lip, gums or upper airway, blood in urine and feces, bruising, rash.
Paleness or fatigue caused by anemia, muscle and joint pain, blurry vision, eye pain.
Vomiting, abdominal pain, diarrhea.
Upper airway pain, difficulty in speaking and swallowing, shortness of breath, comma at large doses.

How Exposures Occur

Absorptioin Through the Skin

There have been cases of individuals with bloody noses hemorrhaging internally and from the mouth after repeatedly handling warfarin without gloves.

Accidental Ingestion

Because warfarin may be applied in liquid, pellet or powder forms, a child could either touch the poison with his fingers, which could be swallowed when fingers are put in the mouth, or he could attempt to eat pellets or powder directly. Baits containing warfarin that are not childproof could be opened by a child, who may then eat the poison.

Inhalation

Warfarin is highly toxic when inhaled, which can occur if the powder form is used.

Significant Statistics

Rodenticides are specifically developed to kill mammals making them risky to humans as well.

Fishel, Frederick M. ” Pesticide Toxicity Profile: Coumarin and Indandione Rodenticides.” University of Florida IFAS Extension. 2009. http://edis.ifas.ufl.edu/pi113.

Warfarin and related compounds are the most commonly ingested rodenticides in the United States. There were 13,345 exposures in 1996.

Fishel, Frederick M. ” Pesticide Toxicity Profile: Coumarin and Indandione Rodenticides.” University of Florida IFAS Extension. 2009. http://edis.ifas.ufl.edu/pi113.

Rodents are developing strains resistant to warfarin requiring stronger warfarin formulations to kill them. The stronger poisons pose more risk to humans as well.

Reigart, J. Routt and James R. Roberts. Recognition and Management of Pesticide Poisonings. 5th Ed. EPA. January 8, 2008. http://www.epa.gov/pesticides/safety/healthcare/handbook/Chap17.pdf

Warfarin is a slow acting rodenticide. It can take a week before the rodent population decreases.

Extension Toxicology Network Pesticide Information Profiles. EXTOXNET. September 1995.

http://extoxnet.orst.edu/pips/warfarin.htm.

Solutions

How to detect 3-(alpha-acetonylbenzyl)-4- hydroxycoumarin (warfarin)

Know the ingredients of the rodenticide you are using. Read labels to determine if warfarin 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. New home owners should inspect carefully for rodenticide baits that may have been left by a previous owner.

How to minimize exposure to 3-(alpha-acetonylbenzyl)-4- hydroxycoumarin (warfarin)

If your child swallows, touches or inhales dust from this rodenticide, contact a poison control center immediately. You may be advised to force the exposed person to vomit by giving them a tablespoon of salt in a glass of warm water.

Alternatives

Make your home unwelcome to rodents. Eliminate the source of rodents’ livelihood, food and water, indoors and outdoors. Use rodent-proof containers. Cover or store pet food dishes when not in use. Keep wood piles off the ground and away from the house. Cut tall grasses and weeds near the house.
Block the rodent doorways to prevent entry. Cover holes (where pipes or cables enter the house, for example) with rodent-resistant materials, such as sheet metal (26 gauge or heavier), perforated metal (24 gauge or heavier with openings no more than 1/4 inch), hardware cloth (19 gauge or heavier with openings no more than 1/4 inch), brick with mortared joints, cement mortar (1:3 mixture) or concrete (1:2:4 mixture).
Set a trap for the pesky mice or rats. Baited traps, such as snap traps, glueboards,and live animal traps, don’t require poisons. (Some glueboards and other traps may use pesticides. Avoid these!) Place the traps where rodents have been seen and near entry points. Remember to check them daily.