EA - Evaluating claims about ContraPest by Spencer Ericson

Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Evaluating claims about ContraPest, published by Spencer Ericson on July 3, 2023 on The Effective Altruism Forum.TL;DR: We conclude that there is some evidence against ContraPest’s claims that the product is “humane,” “it is not an endocrine disruptor,” and “its effects are reversible.” The literature suggests that the active ingredients in ContraPest may cause bone loss, cancer, organ injury, immunosuppression, and endocrine disruption in rats. Any of these could be a risk factor for decreased well-being in rats. VCD may result in permanent sterility in rats over time or at high doses, and at low doses, it results in irreversible premature reproductive senescence.Epistemic status: Uncertain. This was about a 40-hour investigation by me, Spencer, a person with ~no biology background. I conclude that more research is needed into every question I pose. This post will be edited if new information comes in.Quirks: I say “we” because writing “I” in formal writing makes me feel weird. Where I say “We are not aware of studies.” I mean that I searched 3-4 relevant key terms on Google Scholar about that question and came up empty.Acknowledgements: I am grateful to Constance Li for sponsoring this project. I am grateful to Contance Li, Michael St. Jules, and Holly Elmore for feedback. I am grateful to two interviewees for their help. (None of the acknowledged people have endorsed or rigorously fact-checked my claims herein.)IntroductionContraPest is the first and only current EPA-approved contraceptive for Norway rats and roof rats. It was approved in 2016 and brought to market in 2021. ContraPest has received increasing attention; for example, it was featured in Time in March 2023. It is touted as a humane option for rat population control that could replace many use cases for rodenticides. Rodenticides tend to cause prolonged, painful deaths, both for rats and for other wild animals, so ContraPest is thought to be an opportunity to improve wild animal welfare. Its manufacturer, SenesTech, claims that “ContraPest is a non-lethal rodenticide/pesticide that does not bioaccumulate, it is not an endocrine disruptor, and its effects are reversible.”ContraPest contains two chemicals in small amounts, 4-vinylcyclohexene diepoxide (VCD) and triptolide. VCD reduces fertility in female rats by depleting ovarian follicles, which mature into eggs. Triptolide reduces fertility in male and female rats by interrupting the development of ovarian follicles and sperm. However, as we will see below, these chemicals might have side effects like permanent reductions in fertility, cancer, bone loss, organ injury, immunosuppression, and hormone disruption at high doses. More research in needed into the one-time and repeated doses where these side effects become apparent in rats, animals that eat rats, other animals that might come into contact with ContraPest, and humans.We have yet to see a post that thoroughly and critically evaluates SenesTech’s claims about ContraPest. However, we have come to know that “many cities” and at least one animal sanctuary that ran pilots of ContraPest did not continue to use the product due to their concerns about its effectiveness and side effects. To better understand how this product affects wild animal welfare, we attempt to evaluate SenesTech’s claims below. You can skip to the Conclusion, or read the TL;DRs at the top of each section.(We wrote this report after reading Holly Elmore et al.’s sequence for Rethink Priorities, “The rodenticide reduction sequence.” You can read our summary of the sequence here.)QuestionsWe have the following questions about ContraPest. We will only be able to answer some of them.Why did the cities and organizations that tried ContraPest stop using it?At what dose is ContraPest toxic?Is it true that ContraPest causes n...