How to safely use rat and mouse poison

By Tony Burda, DABAT and Grazina Janeliauskaite, Pharm.D. Student

Along with the cooling of outdoor temperatures and the chill in the wind at this time of year we all like to come inside to a nice, warm, cozy home and have a pleasant beverage or snack. But we are not the only ones who have that very same thought in mind. During the brisk fall season, rodents such as mice and rats, are looking to close up their summer nests, pack their bags and make their way into your home through the narrowest of cracks whether you like it or not…EEEK!

So how can we safely evict these unwanted and pesky little guests? There are several ways to prevent entry or eradicate rodents in a residential facility. These include patching any cracks or holes around the foundation, eliminating access to any potential food sources that might draw them inside, setting up traps, and using specific poisons (rodenticides). Our focus will be on the safe use of rodenticides and what to do if an accidental poisoning occurs.

Historically, a number of chemical agents and natural products have been used as rodenticides. Many of these products are known to severely injure humans and domestic animals. Examples of these antiquated, highly toxic products include arsenic, white phosphorus, strychnine and thallium. Even a small taste of any of these substances by a child or a pet may cause serious injury or even death.

In recent years, only four types of chemicals have been accepted for home use. These four agents are effective against rodents and exhibit a greater margin of safety for humans and other animals.  A brief description of the toxic effects to rodents, non-target animals, or humans if consumed in lethal amounts, is as follows :

•  Anticoagulants include brodifacoum, bromadiolone, chlorphacinone, difenacoum, difethialone, diphacinone, and warfarin. Geesh.. try saying that 5 times fast!!  These chemicals work by preventing blood clotting and cause internal bleeding and hemorrhaging. The antidote is vitamin K.
• Bromethalin affects the nervous system adversely by causing brain swelling and seizures.
• Cholecalciferol is vitamin D₃. This is the very same vitamin you will find listed on your multivitamin bottle label. Toxic levels cause calcium in the blood to rise so high that it results in death by cardiac arrest.
• Zinc phosphide is a multi-organ poison which causes bleeding in the gastrointestinal tract and damage to many internal organs such as lungs, heart, liver, kidneys, and brain.

“HEY, aren’t those four poisons pretty scary too?”  The answer: Yes!  Concentrations in these products, however, are typically very low, thus posing a lesser risk of injury from an accidental “taste” by a small child or non-target animal species.  We do wish to make it absolutely clear that although these products may be considered “safer” than those marketed decades ago, everyone must exercise great caution while handling these poisons. We urge everyone  who knows or even suspects an exposure to any rodenticide agent, regardless of quantity eaten, to ALWAYS call the Poison Center at 1-800-222-1222 for immediate assistance and appropriate treatment recommendations.

P.S. Although not considered poisonous, sticky glue boards are traps containing a non-toxic adhesive. Getting this gooey adhesive material on your skin, clothing or hair can create a real mess and make for a very “sticky” situation.  Pun intended. It may take multiple washings with concentrated hand dishwashing liquid to clean everything up.

Here are some tips on using rodenticides safely and wisely as provided by the U.S. EPA:

• Always read and follow package instructions for use.
• Store rodent poisons in original containers. Make sure the ingredients, directions for use, and steps for first aid in case of accidental poisoning are visible on the label.
• Never place the poison pellets in food containers, plates, or bowls that could be mistaken for food by small children and/or pets. It is best to use tamper-resistant bait stations.
• Before placing rodenticides in the house, crawl around on your hands and knees around the areas where you plan to place the rodent baits. This may help you avoid placing the poison in areas accessible to children/pets. Teach children that rodent poison is very dangerous and should never be played with, touched or eaten.
• Store rodenticides in a cool, dry place and in locked cabinets, out of sight and reach of children. It is important to remember that even if the chemical is sold in a child-resistant packaging, it does not mean that the package is child-proof.
• Alert caregivers and family members about the placement and dangers of rodenticides.
• Dispose of old/expired agents properly. Check with your local environmental or solid waste agency, local health department, or call 1-800-CLEANUP to find out the requirements for safe rodenticide disposal. Do not pour leftover rodent poison into the toilet, garbage disposal, or into a sewer or street drain.
• Do not recycle rodenticide containers unless you community recycling program has specific guidelines for doing so safely.

Please feel free to call the Poison Center at 1-800-222-1222 regarding any pesticide question. Trust us, you won’t be a pest. We are more than happy to serve you.