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- Pesticides banned for outdoor agricultural use are regularly used as pet tick and flea treatments;
- The two most commonly used pesticides, imidacloprid and fipronil, are known to cause significant harm to aquatic invertebrates and are found in waterways across the UK;
- One survey found 100% of wash-off samples from treated dogs contained both chemicals.
A new report from wildlife charity Buglife, published on National Love Your Pet Day (20th February), reveals that pesticides from common flea and tick treatments are now widespread in rivers across Britain. These veterinary medicines, used by many pet owners, may be contributing to major declines in freshwater invertebrates such as dragonflies, mayflies, shrimps and damselflies, particularly near wastewater treatment works and urban waterways where contamination is highest.
Love your pet
The UK is a nation of pet owners and veterinary medicines are essential for animal health; they can also help to safeguard humans. Many owners are unaware that treatments contain pesticides including fipronil and the neonicotinoid, imidacloprid, infamously linked to colony collapse disorder in bees. Although both were banned for outdoor agricultural use in the UK in 2018, they remain widely used in pet products, with monthly and preventative treatments increasing overall use. These chemicals are not removed by wastewater treatment plants or septic systems, allowing them to enter rivers.
How big is the problem?
Buglife’s desk-based review found both pesticides pose significant risks to aquatic invertebrates, disrupting food webs and ecosystem functions, with knock-on effects for fish and birds. In 2022, fipronil was the highest-ranked organic contaminant in English ground and surface waters, and in 2023, imidacloprid posed the greatest risk across the Greater London catchment.
Pesticides can reach waterways through dogs swimming, moulted fur, and washing pets or their bedding. One survey found 100% of wash-off samples from treated dogs contained both chemicals.
What can be done?
To protect freshwater life, Buglife is urging the Government to act fast. Recommendations include:
- Reclassifying all veterinary products containing fipronil and imidacloprid as prescription only.
- Improving guidance on environmental risks.
- Prohibiting the online sale of all veterinary products that include harmful pesticides.
- Ensuring a rapid transition to risk-based treatments.
- Revising veterinary package offerings and promoting alternatives.
This report arrives amid a growing awareness of the issues surrounding our ecosystems, as reflected by the efforts of various groups and organisations. Recent studies, reports, and news coverage focusing on rivers, songbirds, and fish highlight shared concerns and underscore the urgent need for coordinated action.
“Freshwater biodiversity is in crisis, and flea treatments are part of the problem. These products are being routinely applied to our pets whether they have fleas or not, and the residues are contaminating our homes and poisoning our rivers and streams at concentrations that are devastating to invertebrates. This cannot continue. We need urgent, decisive action to keep the most harmful substances out of our waterways before the damage becomes irreversible.” Craig Macadam, Co-Leader and Director of Conservation, Buglife.
View and download the full report: The effects of veterinary tick and flea treatments on freshwater invertebrates and ecosystems