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Executive Summary

Around the world, poison is a frontline rodent control management tool. Typical pest management of rodents consists of trying to reduce obvious food and shelter available to them and then poisoning some of the animals when their numbers get large enough that their presence is noticeable. The chemical agents used to kill rodents are known as “rodenticides.” All rodenticides are cruel, but some especially so, and different rodenticides have different non-target effects, such as danger to human children, pets, and other wildlife. The goal of this report is to understand the current practices in rodent pest control and identify levers to improve the welfare of the rodents. This paper describes the past and current rodent pest control landscape with a particular focus on harms of rodenticides and the possibilities for rodent birth control as a cruelty-minimizing alternative. Because rodent birth control is most available in the United States, the focus of this paper is primarily on the U.S.

Controlling a pest population can also be achieved through reducing births, greatly reducing the need for lethal control means. Methods for reducing births include:

  • Resource reduction (by e.g. containing food waste)
  • Habitat reduction (by e.g. filling in abandoned burrows or filling in cracks that give access to the interior spaces of walls)
  • Effective birth control agents (such as EPA-approved ContraPest)

It is often not feasible to practice ideal humane rodent pest control, and for many, humaneness is simply not a priority when addressing a rodent infestation. However, there are practical alternatives that reduce rodent suffering and death without being as difficult or expensive to implement. Rodent birth control can be used in concert with lethal control methods that are more humane than rodenticides, such as traps and asphyxiants that provide quick deaths. These methods and their relative humaneness and effectiveness are discussed.

Other alternatives that have been offered to replace rodenticides unfortunately have not been proven effective or would present serious challenges. Apart from ContraPest, most of the known chemicals that reduce rodent fertility have not been developed to be sufficiently effective, cost-effective, or safe to be competitive with lethal control agents. Many advocates are excited about the potential of single-dose sterilants, which would completely abolish fertility in one dose, to replace rodenticides because the application would be very convenient and similar to single-dose rodenticides. But such a strong sterilant would come with a higher risk of overdose, bioaccumulation, and the evolution of resistance. 

Finally, the report considers the direct impact of replacing rodenticides with ContraPest. Future reports will cover the indirect effects of reducing rodenticides and what interventions are best to reduce the use of rodenticides in the U.S.

This research is a project of Rethink Priorities. It was written by Holly Elmore. If you’re interested in RP’s work, you can learn more by visiting our research database. For regular updates, please consider subscribing to our newsletter.

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I really appreciated this in-depth post, both because it seems like a well researched analysis of a problem with some concrete suggestions and because it's easy to read at different levels; the section headers and summaries made it really easy to get a sense of the overall take and then dive deeper into the sub-topics that I was most confused about. 

Thank you! I was hoping it would be useful to people to consult just the heading they were curious about.

Reading this paper, and its description of rodenticide deaths, made me sad. I appreciate the work y'all do.

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