Dangers of Rodenticides

For many Orange County residents and business owners, rodents are seen as a pest, a terror, an enemy that needs to be exterminated. Often, people end up taking what they believe to be the easiest way out to remedy the situation – rat poison. The strategy is straight forward, easy to implement, and requires very little thought or upkeep. However, the question is: Does it actually solve the problem and at what cost?

Picture of a poison bait box using anticoagulant rodenticides (Photo by Tim Scrivener)

The most dangerous of rodenticides are called anticoagulant rodenticides and they work by preventing the synthesis of vitamin K in the body which is needed for normal blood clotting. The anticoagulant in these rodenticides acts as a blood thinner – using the same chemical in the prescription medication, Coumadin. This causes the consumer to bleed to death slowly and painfully. In the amount of time it takes for the victim to die, the rodent is still a part of the surrounding ecosystem and can be eaten by non-targeted species who then become secondarily poisoned and are at risk of death. Many of these non-targeted species include coyotes, foxes, owls, hawks, and mountain lions. Unfortunately, many mountain lions that have been tagged and studied have been found to have some exposure to these poisons. Often, the level of poisoning is dangerously high which can lead to mange, emaciation, and eventually death. This is worrisome because mountain lion populations are declining here in Orange County.

L.A. mountain lion named P-30 was a high-profile death caused by anticoagulant rodenticides back in 2019. This mountain lion was the first male in the National Park Service’s local study to survive into adulthood after it had been tagged as a kitten 6 years prior. This is the sixth mountain lion from the study that has died of rodenticide poisoning. (Photo by National Park Service)

Ironically, these animals are all a form of free, natural rodent control since they commonly eat rats and mice. Actually, many experts say that allowing predators to naturally prey on rodents is considered to be the most effective approach to rodent control. In fact, one single family of barn owls can eat up to 3,000 rodents per breeding season!

These rodenticides are also directly eaten by many other animals other than mice and rats. The poison is meant to smell like food and can therefore attract other species such as squirrels, skunks, raccoons, birds, and even domesticated pets. In fact, dogs and cats are at extreme risk of poisoning because they live in such proximity to the rodenticides. They can be both directly poisoned if they have access to the bait and secondarily poisoned from eating affected rodents.

Barn owl feeding its chicks. If this rat had recently eaten anticoagulant bait, then these chicks could die from secondary exposure. (Photo by Christophe Perelle)

On top of its ecological impacts, rat poison poses a health risk to humans as well. 10,000 children in the U.S. each year are dangerously exposed to rat poisons which can cause internal bleeding, coma, vomiting, diarrhea, and even death.

The EPA is moving towards restricting the use of rodenticides, however, not without pushback from the companies selling these products. The pesticide industry and health officials stress the importance of controlling rats for the sake of public health because they can spread various diseases. Nonetheless, using poison – battling one health risk with another health risk – should be the last resort in controlling the rat population.

There are many alternatives to rat poison that do not pose such a risk to wildlife, pets, or humans. For one, keeping your property free of clutter and left out food is the best way to prevent rodents from inhabiting your property. There are plenty of humane, catch-and-release traps and repellents on the market that are affordable and easy to use. Attracting natural rodent predators, which can significantly reduce the rodent population in the area, is a natural way to provide pest control. For example, owl boxes, which provide an attractive home for owls, can be installed on or near a property with very little maintenance and no risk to humans. This is an easy, affordable, effective solution to a rodent problem that encourages natural predator-prey relationships, keeps poison from bioaccumulating in wildlife, and provides for some great bird watching from your backyard!

You can help stop the use of these dangerous poisons by communicating these concerns to local and federal policy makers. Write letters to your local representatives, start petitions urging for the banning of these poisons, and spread awareness to friends and neighbors. Many property managers and HOA’s use rodenticides to keep the premises “clean” but you can discourage their use by pointing out the dangers it poses to children, pets, and the environment and suggest alternatives. With passionate activism, we can get anticoagulant rodenticides off the market and prevent inhumane sickness and deaths of people, pets, and wildlife.