BRIDGTON — The proliferation of easily available poisons coupled with rodent paranoia has numbed our sensibilities, to the detriment of the ecosystem. Walk into any grocery, hardware or building supply store and you will come across large displays of rodenticides, also known as “rodent-killing poisons.” Walk around the exterior of many local businesses and homes and you are likely to see innocuous black boxes that contain poisonous bait. The word “rodenticide” implies that only rodents are killed, but it’s a misnomer because all animals, including human and aquatic life, can die from ingesting or inhaling these poisons.

Most brands are touted as “mouse killer” and “resistant to weather and to tampering by children and dogs.” Sounds like a perfect solution to a mouse, rat and/or mole problem, but look at the fine print or go online for details and the warnings are alarming. The following is typical of statements found on manufacturers’ websites. “CAUTION: ENVIRONMENTAL HAZARDS: This product is extremely toxic to mammals and birds. Dogs, cats and other predatory and scavenging mammals and birds might be poisoned if they feed upon animals that have eaten this bait. … Do not contaminate water when disposing of equipment wash water … Any person who retrieves carcasses or unused bait following application must wear waterproof gloves. Keep and wash (clothing) separately from other laundry. … Wash hands thoroughly after applying bait and before eating, drinking (and) chewing gum.”

Commonly sold brands have different formulas of poison. Bromethalin, an active ingredient found in a widely marketed product, is a nerve poison that is fatal if inhaled or swallowed and has no antidote. Bromethalin is a single-dose killer, which means that if an animal eats the bait directly it will be killed, but poisoning can also occur when another animal, such as a fox or an eagle, eats the poisoned mouse, rat, chipmunk or squirrel. Since predators are also nature’s rodent control, it is even more imperative that we do not use poison, so that they can do their part to keep rodent populations in check.

Another common bait poison is cholecalciferol. This poison causes kidney failure within two to three days, has no antidote and is also poisonous to wildlife and pets that eat a sick or dead rodent.

Zinc phosphide is a bait that, when mixed with fluids in an animal’s stomach turns into phosphine, a very toxic gas. When dogs are induced to vomit after eating the bait, people have been sickened from inhaling the resulting gas.

Bromadiolone is an anticoagulant rodenticide that can be applied only by a licensed operator. Animals that eat this poison bleed internally to death. Residues of anticoagulants can remain in the liver for many weeks, so predators – including dogs and cats, foxes, bobcats, hawks, eagles and owls – are at risk of death if they eat poisoned rodents. It is no surprise that veterinarians and wildlife rehabilitation shelters are all too familiar with the sickness and death caused by these poisons.

So what is the solution to rodent control? Prevention is the best cure because it is also humane. Blocking entry points and removing food and water sources are a start. To find entry points around foundations, shine light along the sill at night and have someone on the other side look for light that shines through. The snap trap is environmentally safe, cheap and relatively humane. An indoor cat is a good mouse exterminator. Catch-and-release traps are effective. I evacuated over seven mice from our garage with mouse catch-and-release traps, and while many friends and my husband joked that I was repeatedly catching the same mouse, that was not the case, because our garage has been mouse free for many years.

As a side note, I noticed that the online reviews of the rodenticide Tomcat were all positive, so I sent in a comment that noted that in fact this poison is nonselective and is indeed toxic to children, pets and wildlife. The response I received shortly stated: “Our staff has read your review and values your contribution even though it did not meet all our website guidelines. Thanks for sharing, and we hope to publish next time.”


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