For a pet owner who wants to keep their dog or cat free of fleas, flea treatments seem like a good idea. But new research suggests that toxic chemicals in these treatments have a far greater reach — and pollutive impact — than previously suspected.
What's happening?
The University of Sussex and Imperial College London recently published research in the journal Science of the Total Environment that tracked the presence of two insecticides — fipronil and imidacloprid — found in some of the commonly used over-the-counter flea treatments. Researchers found that not only did the chemicals linger on the hands and in the homes of pet owners for 28 days after application, but their residue drained into and contaminated local water sources.
Many flea treatments, especially those by prescription, do not contain either ingredient; The New York Times recently published an unrelated list of common flea treatments and their active ingredients here. Many veterinarians have already been advising dog owners against using flea treatments such as Frontline for this reason for years, and the new study helps to reinforce that.
Dave Goulson, a biology professor who oversaw the research, told the Guardian: "These two chemicals are extremely potent neurotoxic insecticides and it is deeply concerning that they are routinely found on the hands of dog owners through ongoing contact with their pet. Pet owners will also be upset to learn that they are accidentally polluting our rivers by using these products."
Why are these chemicals so harmful?
Imidacloprid belongs to a group of chemicals called neonicotinoids, or neonics, which are also used widely as insecticides. However, research on the dangers of neonics has led to their being banned in the EU. At this time, the U.S. Environmental Protection Agency still allows neonics to be used in agriculture.
Neonics have been linked to neurological issues, birth defects, heart damage, and memory loss. And with neonics still measurably present in households a month after applying flea treatment, Goulson says, proper risk assessments for these treatments need to be made.
"If they're on our hands then these neurotoxins will be all over our homes," he said. "That doesn't sound healthy to me."
This discovery raises substantial concerns for families, particularly with young children and pets, who may be at heightened risk from prolonged exposure to neurotoxins within their homes. Community awareness and safer practices in flea treatment can significantly reduce this hidden health hazard.
These toxins are also harmful to wildlife, from birds to deer, fish, and more. Guy Woodward, an ecology professor who was also involved in the research, said that "despite these chemicals being banned from outdoor agricultural use for several years, we are still finding them in UK freshwaters at levels that could harm aquatic life."
And unfortunately, it seems that flea treatments are a much larger contributor than previously thought. The research found that they accounted for an estimated 20-40% of wastewater pollution.
The preservation of wildlife and the environment is important as well because ecology is often a delicate balance, where one struggling species of animal or plant can suddenly cause a domino effect leading to any number of other problems.
What's being done?
"I would argue that vets should stop encouraging dog and cat owners to use these treatments prophylactically," Goulson suggested. "If an animal hasn't got fleas, why would you treat it for fleas?" He also advised washing pet bedding often to kill larvae.
When it comes to agricultural use, many groups are pushing for a full ban. But until then, some researchers are looking to optimize application to avoid over-spraying, while others are investigating alternative methods for keeping insects at bay.
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