Harvard Law School’s Animal Law & Policy Clinic and local wildlife advocates join a growing chorus of scientists, towns, and state officials demanding an end to the use of toxic rodenticides that kill wildlife and pose a risk to public health in favor of safer alternatives.
CAMBRIDGE, MA — A coalition of Massachusetts wildlife advocates, represented by the Harvard Law School Animal Law & Policy Clinic, is urging the Massachusetts Department of Agricultural Resources (MDAR) to end the use of toxic and dangerous rodenticides statewide. In a public comment submitted to the Pesticide Board Subcommittee on March 20, the Clinic urged MDAR to find that these chemicals pose environmental and public health risks that render their continued use illegal under Massachusetts state law.
Anticoagulant rodenticides (ARs), including both first (FGARs) and second (SGARs) generation, are widely used in Massachusetts by pest control companies in an attempt to control rat and mice populations. Death is caused by fatal internal bleeding — a process that can take days to weeks. Because the poisons accumulate in tissue and persist long after a rodent consumes them, any animal that eats a poisoned rodent is at risk of poisoning as well.
Despite Massachusetts’s ongoing environmental restoration efforts, even state-protected species are being adversely affected by rodenticides. “Animals protected by the Massachusetts Endangered Species Act, including multiple bald eagles, have been poisoned by ARs,” says Abigail Baldauf, a student in the Clinic. “The reality is that as long as ARs are used, these animals risk suffering a prolonged and gruesome death.”
A scientific review recently commissioned by the Pesticide Board Subcommittee found that AR exposure among Massachusetts wildlife has reached alarming levels. Every owl admitted to the Tufts Wildlife Clinic over a recent study period tested positive for ARs. The rate of exposure in red-tailed hawks grew from 1.3% in 2006–2010 to 91% by 2017–2019. Massachusetts wildlife officials have documented harmful effects across species including foxes, fishers, bobcats, and coyotes. Local wildlife advocates, including Save Mass Wildlife and Cape Ann Wildlife, have observed similar impacts with a majority of animals tested by the advocates showing exposure to ARs in lethal range. That data was shared with MDAR but, despite the seriousness of these findings, the agency refused to allow the data to be considered in the scientific review of ARs.
“Given the overwhelming evidence in the scientific literature and the substantial dataset submitted to MDAR showing the localized impacts of ARs on Massachusetts wildlife, and given the fact that there are so many readily available alternatives for rodent control, the pesticide subcommittee needs to stop rolling the dice with these poisons and remove their registration.” Marci Cemenska, Save Lexington Wildlife.
The concern extends beyond wildlife. Nationally, children under six accounted for nearly 89% of all AR exposure cases reported between 1987 and 2012. In 2024, the National Poison Data System continued to report thousands of cases of AR exposure, 60% of which involved children under six. Companion animals are also at risk: one study of dogs exposed to anticoagulant rodenticides over a ten-day period recorded no survivors.
Given this body of evidence, the Massachusetts Pesticide Control Act requires the Subcommittee to deny re-registration of anticoagulant rodenticides for use in the state. The law permits registration of a pesticide only if it does not cause unreasonable adverse effects on the environment — a standard ARs plainly fail. Many effective, less harmful alternatives exist, including Integrated Pest Management strategies that use exclusion, sanitation, and mechanical traps. In some studies, predator-based biological controls have proven more effective at reducing rodent damage than ARs.
The push to ban ARs has broad support in Massachusetts. Governor Healey’s administration has explicitly identified eliminating harmful pesticides, including SGARs, as a goal of its biodiversity initiative. The Massachusetts Department of Fish and Game has publicly urged residents to avoid the use of ARs. Towns including Arlington, Lexington, Bedford, and Salem have bills pending before the state legislature seeking authorization to ban ARs locally. According to Mass Audubon, 106 communities across the state are organizing against the use of ARs.
“The law, facts, scientific research, and wide availability of cost-effective alternate products and services are a mandate for change. There are no more excuses for the continued usage of AR products in our environment.” Jim Joyce II, Friends of Horn Pond.
The Subcommittee’s overdue review presents an opportunity for Massachusetts to ensure that it is complying with the law, with the directives of this administration, and with public opinion by ending the use of ARs in the state.