(Beyond Pesticides, March 5, 2021) Pet owners will be alarmed to read the report, by USA Today, that a popular flea and tick collar — Seresto, developed by Bayer and sold by Elanco — has been linked to nearly 1,700 pet deaths, injuries to tens of thousands of animals, and harm to hundreds of people. At the time of publication, the U.S. Environmental Protection Agency (EPA), which regulates pesticides, had issued no informational alert to let the public know about these risks to pets — despite many hundreds of incident reports in its Office of Pesticide Programs Incident Report database. Beyond Pesticides and other advocates have warned of the toxicity of pet pesticide treatments, not only to the animals themselves, but also, to children and other household members. There are nontoxic ways to protect pets from fleas and other pests, and to protect human family members at the same time.
Beyond Pesticides is calling on EPA to recognize, finally, that the label on flea collars is not adequately protective, as evidenced by the number of deaths and 75,000 incidents. “EPA has the authority to act now, and it should use its powers to protect the health and lives of pets,” said Jay Feldman, executive director of Beyond Pesticides. “The deaths should trigger immediate action as EPA studies the situation—not the reverse—as it did with the herbicide Imprelis when trees where killed after the product’s use,” said Mr. Feldman. In 2011, EPA issued an order to E.I. DuPont de Nemours (DuPont) directing the company to immediately cease the distribution, sale, use or removal of Imprelis herbicide products under its ownership, control, or custody. The agency found that, “The directions for use and/or warning or caution statements on DuPont’s Imprelis labeling are inadequate.”
Last year, in covering a different pet-related issue, Beyond Pesticides wrote this: “Humans and dogs often occupy similar spaces, exposing both species to the same chemical contaminants, like pesticides. . . . Pet products containing pesticides are of concern as people encounter their pets daily. With the high degree of human contact with pets, through cuddling and hugs and kisses, those using pet products containing pesticides are at greater risk of high contaminant exposure. Numerous flea and tick prevention products (e.g., collars, topical treatments, sprays, dusts) include pesticides like tetrachlorvinphos (TCVP), propoxur, synthetic pyrethroids, and fipronil. A common trait among these pesticides is their toxicity, not just to dogs and nontarget organisms, but to humans, as well.”
The active pesticide ingredients in the Seresto pet collars are imidacloprid and flumethrin. The neonicotinoid insecticide imidacloprid is a commonly used pesticide associated with serious health and environmental decline. It is a neurotoxicant, an endocrine disruptor, an immunosuppressant, linked to cancer, and also has negative reproductive impacts. It is toxic to birds, bees, and aquatic organisms, and persists in aquatic environments. In 2016, EPA released an assessment of risks of its use to honey bees that showed a strong link between use of imidacloprid and severely declining bee populations. The compound is banned for outdoor use across the European Union, but allowed in pet collars. In late 2020, Beyond Pesticides wrote about another harm of pet flea treatments: contamination of waterways with imidacloprid (and other pesticide compounds), in both England and the U.S.
Flumethrin is a chemical in the pyrethroid class of synthetic neurotoxic insecticides, which have been repeatedly linked to neurological issues, such as seizures and learning disabilities in children, and to gastrointestinal distress, as well as to damage to non-target invertebrates, according to EPA’s own analysis. It is deployed on domestic pets (via collars) and on livestock for control of fleas and ticks, and is even marketed for control of varroa mites in beehives.
The Seresto collars contain both these compounds, although — according to the Rachel Carson Council — imidacloprid likely has a minor, if any, role in the dog mortality on which USA Today reports. Flumethrin and “inert” compounds, or synergies among those and the active ingredients, may be the culprits.
EPA nevertheless continues to permit use of the Seresto collars despite the demonstrated risks to children of flumethrin, in particular. In 2016, the agency issued a bulletin that asserted that the collar label includes the following language: “DO NOT LET CHILDREN PLAY WITH THIS COLLAR OR REFLECTORS; KEEP OUT OF REACH OF CHILDREN.” The bulletin further states, “Flumethrin exposures to people placing collars on pets, and to adults and children interacting with pets (including incidental ingestion because of children’s hand-to-mouth activities), are below levels of concern. The assessment of imidacloprid identified no risks to humans placing the collars on pets or interacting with pets wearing the collars.” And it reiterates, “As stated in the precautions on the label, do not allow children to play with the collars. In addition, try to keep the pet away from young children for a day after putting on the collar to minimize exposure.” EPA’s use of ALL CAPS and repeated warnings about children suggests a high level of agency concern.
That same EPA bulletin says, “The risk of the combination of the two active ingredients, flumethrin and imidacloprid, was not assessed because the two chemicals act in completely different ways.” This failure to evaluate synergistic effects of pesticides is typical of EPA. As Beyond Pesticides has pointed out repeatedly, EPA does not do an adequate job of evaluating the risks and harms of exposures to multiple pesticide compounds, as well as those of so-called “inert” or “other” pesticide ingredients.
USA Today writes, relatedly, “A 2012 Bayer study found [these two compounds] have a ‘synergistic effect,’ meaning they are more toxic together on fleas. . . . Additionally, eight companion animal safety studies were conducted by Bayer looking at the effect of Seresto collars on domestic cats and dogs. The EPA used these studies to approve Seresto. . . . Another issue could be a reaction of inactive ingredients, which are unknown and have caused problems in spot-on treatments [according to Nathan Donley, PhD, a senior CBD scientist and an expert on U.S. pesticide regulation]. . . . [Dr. Donley] said this ‘synergistic effect’ likely extends to pets. He said he wasn’t sure what makes the two pesticides so likely to cause harm, but it is clear something is wrong with the product. . . . ‘You don’t even see these kinds of numbers with many agricultural chemicals. For whatever reason, this combination is just really nasty.’”
These products, such as the Seresto collar, are meant to stay on dogs or cats for months at a time, and kill fleas, ticks, and other pests. The Seresto collar has caused, apart from pet deaths, rashes, seizures, motor dysfunction, fatigue, diarrhea, vomiting, and excessive drooling. The product label indicates the collar is for external use only; but that direction does not account for the fact that dogs and cats clean themselves (by licking their fur) frequently, and can ingest the collar’s pesticides because it is designed to release and disperse them onto fur and skin steadily over the course of months. Mammals generally tolerate pyrethroid insecticides such as flumethrin relatively well — unlike insects, for whom the toxicity is 1,000 times higher. But with chronic exposure, such as sustained skin or inhalation exposure, as the collars allow, or after direct contact with open wounds, the toxicity can be much higher, and pets can experience more-severe impacts.
Pet owners likely do not think about the flea and tick collars they use on pets as toxic. Manufacturers and EPA represent that they are safe for the pets themselves, yet federal documents secured through the Center for Biological Diversity’s (CBD’s) FOIA (Freedom of Information Act) request, and shared with the Midwest Center for Investigative Reporting, chronicle the incidents of harm: at least 1,698 related deaths of pets (dogs and cats), nearly 1,000 cases of negative impacts on humans, and more than 75,000 incidents overall.
EPA has logged these “Seresto” incidents in its database for years, but has not seen fit to warn the public. Karen McCormack, a retired EPA scientist and communications officer, notes that these collars have garnered the greatest number of incident reports of any pesticide product in her long experience. She says, “EPA appears to be turning a blind eye to this problem, and after seven years of an increasing number of incidents, they are telling the public that they are continuing to monitor the situation. But I think this is a significant problem that needs to be addressed sooner rather than later.”
An EPA spokesperson recently said that, despite these incidents, the agency has deemed Seresto collars “‘eligible for continued registration’ based on best available science, including incident data. . . . No pesticide is completely without harm, but EPA ensures that there are measures on the product label that reduce risk. The product label is the law, and applicators must follow label directions. Some pets, however, like some humans, are more sensitive than others and may experience adverse symptoms after treatment.”
The Seresto collars are sold by retailers such as Amazon, Petco, Chewy, and PetSmart. Amazon has received dozens of complaints over time about pets developing rashes and neurological issues with use of the collars. All of these retailers continue to sell these products.
The Seresto issue represents the latest of EPA’s failures to regulate pet pesticide products so as to protect animals and the humans in their households. In 2009, the Natural Resources Defense Council (NRDC) sued the agency over its approval of tetraclorvinphos, or TCVP, an organophosphate insecticide used in pet collars as well as on livestock. In addition to typical neurotoxic organophosphate impacts (numbness, tremors, incoordination, blurred vision, respiratory depression, and brachycardia) on the animals, TCVP represented human exposures through pets, livestock, and dietary and water exposure (because of the livestock use). The NRDC case called for cancellation of TCVP’s registration by EPA.
In 2016, EPA announced its allowance of continued use of TCVP, despite the inadequacy of the labeling on TCVP products to protect children, who are uniquely vulnerable to the compound’s neurological effects. As Beyond Pesticides wrote, “Children face unique hazards from pesticide exposure. They take in more pesticides relative to their body weight than adults in the food they eat and air they breathe. Their developing organ systems often make them more sensitive to toxic exposure. The probability of an effect such as cancer, which requires a period of time to develop after exposure, is enhanced if exposure occurs early in life.”
In April 2020, the U.S. Ninth Circuit Court of Appeals gave EPA a deadline for responding to the court’s previous writ of mandamus to respond to NRDC’s petition for cancellation of the registration of TCVP. EPA had already delayed response by more than a decade, about which the court wrote, “Repeatedly, the EPA has kicked the can down the road and betrayed its prior assurances of timely action, even as it has acknowledged that the pesticide poses widespread, serious risks to the neurodevelopmental health of children.” NRDC’s lawsuit is ongoing.
Pet collars containing TCVP continue to be sold under the brand name Hartz Ultraguard, Hartz InControl, and Longlife. The number of incidents related to the use of the Seresto collar, however, dwarf the number related to TCVP. (From 1992 to 2008, the EPA received roughly 4,600 incident reports related to collars containing TCVP, including 363 deaths, according to agency documents.) Reported Serestro incidents, which CBD asserts are likely undercounts, on the other hand, include:
- 907 human incidents
- 1,698 domestic animal fatalities
- 3,767 major domestic animal incidents
- 7,743 moderate domestic animal incidents
- 21,439 minor domestic animal incidents
- 40,087 classified as “moderate, minor, and unknown domestic animal incidents”
Of those 907 human incidents reported, 19 were severe, and of those, eight people experienced skin rashes or hives, and seven had neurological symptoms, including headaches and paresthesias (numbness, tingling, or burning sensations).
CBD’s Nathan Donley calls the number of reported incidents for Seresto “just the tip of the iceberg.” He says most pet owners will not, automatically or at, all make the connection between a pet’s illness or dysfunction and the flea collar. His criticism of EPA behavior on this matter is scathing: “If this [level of negative incidents] doesn’t trigger a concern, that’s a fundamental problem with the process. The fact that EPA has not done anything to alert the public that there might be an issue here . . . strikes me as bordering on criminal. The EPA has this system in place to compile information and it’s just collecting dust in some database.”
EPA did not respond to a request about how the magnitude of incidents related to the Seresto collar compares with those related to other flea and tick collars. The Midwest Center for Investigative Reporting has filed a FOIA request for the incident database, but has not yet received the information.
Absent EPA notification of the public on the dangers of these pet collars, despite tens of thousands of complaints, people have taken to the Internet to learn what they can and find others with similar experiences. Pet owners whose pets have taken sick or died — and who put two and two together to identify the collars as potentially causal — have posted warnings, including a letter in the St. Louis Post-Dispatch in 2013, a New York radio news story in 2016, and many comments on digital forums devoted to pets.
One owner who lost pets to these collars is Ron Packard of Brockton, Massachusetts, who created a Facebook page for others who have lost pets in this way; the page is packed with stories similar to his own. USA Today writes, “Packard encourages everyone to report their stor[ies] to the EPA. ‘I don’t want others to go through what we went through. Every time I read the stories, it brings me back to my dogs. But if I can save a few pets, I can deal with it.’”
Until EPA acts to protect pets by deregistering these flea and tick collars, dog and cat families can take steps to ensure their beloved pets are not negatively affected by these products (or insecticide dusts or sprays or shampoos). Certainly, veterinarians may be able to suggests alternatives. In addition, check out Beyond Pesticides’ page on Keeping Our Companions Safe, its guide to least-toxic controls for fleas, and its comprehensive guide to keeping pets safe. NRDC also offers guidance on its website: Nontoxic Ways to Protect Your Pet.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.