12
Jun
Adding to Similar Findings, Study Finds Anticoagulant Rodenticides Harm Nontarget Organisms
(Beyond Pesticides, June 12, 2025) Thailand-based researchers, in a study published in BMC Veterinary Research, found significant documentation of the occurrence of anticoagulant rodenticide (AR)-induced toxicosis for nontarget organisms in the country. This includes the finding that “all submitted samples of suspected AR exposure in wild animals and exotic pets tested positive for ARs.†These findings signal the pervasive nature in which agrichemical products, including anticoagulant and nonanticoagulant rodenticides, encroach on broader ecosystem health. In an era of federal deregulation and increasing public scrutiny of the role of government in addressing public health, biodiversity, and the climate crisis, advocates continue to call for a wholesale transition to organically managed food and land management systems.
Background and MethodologyÂ
“In this retrospective study, we investigated the occurrence of AR poisoning in animal specimens analy[z]ed at the Department of Veterinary Pharmacology, Faculty of Veterinary Science, Chulalongkorn University (DVPCU), between 2018 and 2023,†say the authors on the primary focus of this study. “This study aims to provide a reference dataset for future research on the epidemiology of AR toxicosis in nontarget species.†The authors declared that there were “no competing interests†in engaging in this research.Â
The anticoagulant rodenticides were detected through two forms of chemical analysis: “thin layer chromatography (TLC) and spectral analysis via derivative spectrophotometry.†There were 55 animal cases submitted to DVPCU for this study, including “43 dogs, 6 cats, 3 Patagonian maras, one goose, one turkey, and one wild boar.â€Â
ResultsÂ
“Among these cases, 35 (63.6%) tested positive for AR poisoning using both TLC and spectrophotometry methods ()[,]†says the authors in this study. “Within the AR-positive group of 35 cases, dogs accounted for 27 cases (77.1%), followed by two cats (5.7%), one goose (2.9%), one turkey (2.9%), one wild boar (2.4%) and 3 Patagonian maras (8.6%).†It is important to note that the “Cohen’s kappa value was 0.421, indicating moderate agreement†between the AR-positive test results for the various intestinal tissue samples included in this study. As stated by the authors, “[T]he most prevalent lesion observed in all submitted specimens was hemorrhage in the liver.â€Â
Cohen’s kappa value is utilized in research settings to capture the strength of the interrater reliability for this study, which refers to the “reproducibility†of the same measurement (i.e., ecotoxicological impact of a rodenticide) among multiple scientists or scientific teams. (See here and here for additional information on kappa value and interrater reliability.)Â
“In terms of specimen types, liver samples have proven to be the most appropriate for detecting ARs due to their high accumulation. . .,†say the study authors. The authors suggest “that stomach content analysis [for AR-induced Toxicosis] may be a useful complementary tool alongside liver testing, which has not been previously reported†in the existing scientific literature. Considering that certain laboratories may not host suitable equipment to adequately scan for AR toxicity, the authors view this development as critical for future research.Â
Previous Research and ActionsÂ
There are a significant number of peer-reviewed studies that document the toxic nature of rodenticides.Â
Second-generation anticoagulant rodenticides (SGARs) have been found in the tissue of various aquatic and terrestrial organisms, leading researchers and conservationists to increasingly scrutinize the role of toxic pesticide drift from bait stations to streams, forests, and other habitats. See our previous Daily News, Research Highlights Regulatory Failures in Addressing Risks to Nontarget Organisms from Rodenticides, for additional analysis on some of the latest peer-reviewed research out there on rodenticides.Â
Beyond Pesticides has submitted comments to the U.S. Environmental Protection Agency (EPA)’s Office of Pesticide Programs, including in early 2024, expressing disagreement with the categorical no effect (NE) determinations for all freshwater and marine fish, aquatic mammals, aquatic amphibians, aquatic reptiles, and aquatic invertebrates. (See here for Daily News, here for Action of the Week, and here for EPA comments.) In response to continuous concerns raised by the public that their beloved pets and wildlife are being poisoned by toxic substances, including rodenticides, in 2023 EPA announced the release of over a decade worth of pesticide incident data in a searchable database that will be updated on a monthly basis through the Incident Data System (IDS). (See Daily News here.) According to an analysis at the time by the Center for Biological Diversity, 1,169 incidents involve the toxic PFAS rodenticide brodifacoum, one of the most widely used rodenticides in rat poison products.Â
Unfortunately, by the agency’s own admission, it has “limited confidence in the accuracy and validity of the data because the data entries are reports of one or more individuals’ perspective of what happened.†Rather than take a precautionary approach based on the known harms of the substances at hand, EPA continues to prioritize mitigation over prevention of poisonings at the root cause— a systemic failure to improve the regulatory system.Â
See here for additional Daily News coverage on rodenticides and their ecological and public health impacts on people and ecosystems.Â
Call to ActionÂ
There are policymakers taking action to address the issue of runaway pesticide deregulation and rubberstamping of their continuous use in spite of the abundance of peer-reviewed scientific literature indicating severe public health and environmental dangers from anticoagulant rodenticides.Â
On May 7, 2025, the Ministry of Agriculture and Livestock Development in Kenya took significant steps to prevent pesticide poisonings and ecological harms with, as they describe it, “the bold announcement to ban over 50 pesticide products from the Kenyan market.†This action follows a court ruling on March 19 in the Kenya Court of Appeal “blocked the Kenyan government from importing genetically modified organisms (GMOs) into the country[,]†according to a press release by Alliance for Food Sovereignty in Africa (AFSA). See here for the Kenya Ministry of Agriculture’s press release and here for the press release representing civil society commending the government’s action.)Â
In Vermont, there are efforts to pass legislation (H.326) to address the issue of anticoagulant and nonanticoagulant rodenticides in decimating wildlife and undermining ecosystem integrity. “The first step in pest management is pest prevention,†says Jay Feldman, Sara Grantham, and Max Sano in written comments submitted to the Vermont legislature on holistic pest management practices. “IRM is an Integrated Pest Management (IPM) approach that places strong emphasis on sanitation, pest exclusion (which includes addressing human behavior and structural pest proofing), education, and training. To address human behavior, one must focus on food, water, and harborage (FWAH) for rodents. These three factors can help regulators determine the extent of rodent infestation and the causes.” For additional scientific analysis, see our full written testimony here.Â
Are you interested in taking action? Learn more about how to become an advocate for the Parks for a Sustainable Future Program and engage in an Action of the Week.Â
All unattributed positions and opinions in this piece are those of Beyond Pesticides.Â
Source: BMC Veterinary Research
