20
Nov
Flea Treatment Pesticides Found to Contaminate Waterways
(Beyond Pesticides, November 20, 2020) Many pet owners likely do not consider what is actually in the flea treatments they administer to their animals. That should change, and recent research demonstrates why. Scientists sampling rivers in England found extreme contamination with two neurotoxic pesticides commonly used in flea products for dogs and cats: fipronil and the neonicotinoid imidacloprid. In many instances, the concentrations in the waterways were far higher than accepted “safe” levels. Though these compounds are banned for agricultural uses in the United Kingdom (UK), risk assessment for them, as used on animals, has been minimal because of the assumption that the amounts used for veterinary treatments would mean far-less-significant environmental impact than might be expected with agricultural-scale use. This research out of the University of Sussex voids that assumption, and the researchers recommend “re-evaluation of the environmental risks posed by pet parasite products, and a reappraisal of the risk assessments that these products undergo prior to regulatory approval.”
Apart from being an active ingredient in flea treatments for pets, fipronil is used in insect baits, and in turf management and agriculture in the U.S. It is highly toxic to insects, including bees, to birds, and to aquatic invertebrates. (It is particularly harmful to dragonflies.) Health-wise, it has damaging effects on the neurological, reproductive, endocrine, and renal and hepatic systems, and is a possible human carcinogen. Fipronil can have negative health impacts on pets themselves, including skin irritation, convulsions, incoordination, lethargy, and other effects.
Imidacloprid, a neonicotinoid pesticide, is commonly used — aside from pet treatments — in U.S. agriculture, and in lawn and turf management. Commonly considered less problematic than fipronil, it is nevertheless also toxic to bees, birds, and fish and other aquatic organisms; it has some reproductive impacts in humans. Its environmental impact on such organisms was demonstrated in a 2017 risk assessment, through which EPA found that, “[C]oncentrations of imidacloprid detected in streams, rivers, lakes and drainage canals routinely exceed acute and chronic toxicity endpoints derived for freshwater invertebrates.”
In the UK, fipronil is used in 66 different veterinary products, and imidacloprid in another 21; these may be the sole active ingredients in a product, or present along with other parasiticides. Such treatments may be administered via oral ingestion, spray-on application, or collars that harbor the pesticides. Given the UK ban on these chemicals for agricultural uses, pet treatment appears to be the primary source of the pollution in the rivers that were sampled.
The highest levels of contamination were found immediately downstream of wastewater treatment plants, giving credence to the notion that these compounds end up in household drains. Authors cite pet bathing (after flea treatment), laundering of pet bedding and towels used on pets, and even human handwashing (after petting a treated animal) as possible vectors from treated pets to wastewater drains. Others may include dogs swimming in waterways, and rainfall shedding off of pets.
The research paper was published in Science of the Total Environment. Co-author, veterinarian, and U of Sussex PhD student Rosemary Perkins commented, “The use of pet parasite products has increased over the years, with millions of dogs and cats now being routinely treated multiple times per year. . . . Fipronil is one of the most commonly used flea products, and recent studies have shown that it degrades to compounds that are more persistent in the environment, and more toxic to most insects, than fipronil itself. Our results, showing that fipronil and its toxic breakdown products are present in nearly all of the freshwater samples tested, are extremely concerning.”
The researchers analyzed data from river samples gathered by the UK Environment Agency, between 2016 and 2018, from 20 English waterways; they found fipronil in 98% of freshwater samples, and imidacloprid in 66%. Average concentrations of fipronil across the rivers sampled were five times established chronic safety thresholds, making the pesticide and its breakdown products very significant risks to aquatic ecosystems.
From most of the river samples assayed, imidacloprid was thought to represent moderate risks to those ecosystems, although in seven of the 20 waterways, that risk rose to high levels. Given the strong correlation between levels of fipronil and imidacloprid found across river samples, which points to a common source of the pollution, the researchers regard these findings as likely representative of broad presence of these compounds in England’s waterways.
Co-author and Professor Dave Goulson, PhD commented: “Fipronil and imidacloprid are both highly toxic to all insects and other aquatic invertebrates. Studies have shown both pesticides to be associated with declines in the abundance of aquatic invertebrate communities. The finding that our rivers are routinely and chronically contaminated with both of these chemicals and mixtures of their toxic breakdown products is deeply troubling.”
Though banned in the UK, use of these noxious compounds in agriculture continues to be permitted in the U.S. by the Environmental Protection Agency (EPA). Fipronil is recognized as a widespread contaminant of U.S. surface waters. A Fall 2020 USGS (U.S. Geological Survey) study found that both fipronil and imidacloprid were among the most toxic pesticides found in 72 watersheds across the country, and two of several drivers of toxicity to benthic invertebrates. (Benthic invertebrates are those that live on or under the silt at the bottom of waterways, such as nematodes, flatworms, freshwater mussels, crabs, shrimp, clams, et al.). In 2018, the Washington State Department of Ecology proscribed use of imidacloprid in or on Willapa Bay after it determined that “environmental harm from this neonicotinoid pesticide would be too great.”
In addition, research has shown that fipronil can cause transgenerational toxicity in zebrafish and copepods (a type of crustacean), meaning that non-target organisms can be impacted without ever having had direct exposure. In zebrafish, those impacts included a 30% reduction in hatch rates and more than double the typical mortality rate in offspring. More research is needed to understand whether this same phenomenon extends to other species. Another 2020 USGS study revealed that fipronil, ubiquitous in U.S. waterways, is even more toxic to aquatic insects than was previously thought, and can trigger trophic cascades capable of destabilizing entire aquatic ecosystems.
In reporting on that USGS study, Beyond Pesticides wrote, “Despite the high quality of the findings by a U.S. government agency, pesticide regulators at [EPA] do not adequately consider ecosystem-level effects when determining whether to register a pesticide. As a result, without public pressure on the agency, it is unlikely it will follow the science and take the action necessary to rein in use and safeguard the environment.” Earlier this year, Beyond Pesticides wrote, “The environment would be well-served if those tasked with protecting it were to restrict use of this insecticide.”
In the first quarter of 2020, EPA began a registration review of fipronil, as is supposed to happen for each pesticide every 15 years. Registration review means that EPA looks at new information about a subject compound to ensure that it continues to meet the standards of FIFRA (the Federal Insecticide, Fungicide, and Rodenticide Act) for registration — registration being, essentially, permission for, and any constraints on, a pesticide’s use.
When the public comment period was opened on the review of fipronil, the Attorney General of California, Xavier Becerra, wrote in his comments: “If the EPA proposes re-registration of fipronil based on the incomplete and inconsistent draft risk assessments, it may violate FIFRA, which bars registrations that would cause unreasonable adverse effects on the environment.” The Bay Area Clean Water Agencies (BACWA) also weighed in, saying it was “‘surprised and disappointed’ that the draft risk assessment ‘does not even mention the scientific fact that fipronil is discharged to municipal wastewater systems (which) pass through (publicly owned wastewater treatment facilities), and result in discharges that pose ecological risks.’”
Apropos the findings of the UK study, BACWA also called for “an extended risk assessment of fipronil, evaluating sewer discharges from pet flea control treatments. And it is proposing risk mitigation strategies for fipronil products, such as product stewardship labels and requiring pet owners not to wash their pets for at least two weeks after treatment.”
An EPA registration review of imidacloprid began in late 2019, and EPA issued an interim decision on imidacloprid’s re-registration early in 2020. Beyond Pesticides reported: “Despite finding widespread harm to pollinators, birds, and aquatic organisms, the agency is only requiring limited changes around application timing and amounts. It is eliminating use of imidacloprid on residential turf for grubs, and according to a release will be requiring ‘language on the label advising homeowners not to use neonicotinoid products.’ Thus, the agency appears to be approving a product for sale it does not wish people to use.”
EPA should take note of the English study and its recommendations, and pay more attention in its reviews of these pesticides to the “flea treatment vector.” If English waterways are so profoundly contaminated by fipronil and imidacloprid — absent their use in UK agriculture — it can be reasonably speculated that this problem in the U.S. is worse, given that both compounds are permitted for use here. Also supporting that speculation are the facts that 41% of households in the UK have at least one pet, whereas 54% of U.S. households do; most of those are dogs and cats, on which flea treatments are typically used. Ultimately, EPA should follow the UK’s lead, and “ban” fipronil and imidacloprid by not re-registering them.
Source: https://www.sciencedaily.com/releases/2020/11/201117085940.htm
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
