Today, 21^st April 2026, environmentalists, academics and veterinary professionals have written to the Environment Minister, Baroness Hayman of Ullock, warning that two pesticides commonly used in pet flea and tick treatments - fipronil and imidacloprid - are contaminating the UK’s rivers, lakes, ponds and wildlife.

Although both chemicals are banned for agricultural use, they remain widely available in over-the-counter spot-on treatments and collars for pets, often used routinely each month. There are around 11 million dogs and 10.5 million cats in the UK, with more than 75% receiving flea treatment in the last year.

A growing body of scientific evidence links these pet treatments to contamination in waterways. Research funded by the Department for Environment, Food & Rural Affairs found significant amounts of the chemicals are washed down drains. Both substances are frequently detected in UK rivers, often above ecological safety thresholds, and are highly toxic to freshwater insects such as mayflies and dragonflies, which are in the food chain for fish and birds.

New studies from the University of Sussex, published today, provide some of the first evidence that these chemicals are also entering wild birds through contaminated nesting material made from pet fur, raising urgent concerns about wider ecological impacts.

A coalition of environmental and veterinary organisations - including BTO, Friends of the Earth, Greenpeace, RSPB and the Wildlife Trusts - has signed an open letter coordinated by the charities Buglife, WildFish and SongBird Survival. The group is calling on the Government to:

- Set a clear timeline to review how products containing fipronil and imidacloprid are sold

- Make these treatments prescription-only

- Introduce proper monitoring of the chemicals in waterways and fully assess their environmental impact

On the recent scientific findings, Professor Dave Goulson from the University of Sussex commented:

“It was deeply concerning to discover that potent insecticides, long banned in agriculture but still used as spot-on flea and tick treatments on pets, are widely contaminating rivers and are also found in blue tit and great tit eggs and chicks and in feathers of adult songbirds. This widespread environmental contamination is unacceptable. Defra need to take regulatory steps to sort this mess out as a matter of urgency.”

Sue Morgan, CEO of SongBird Survival added:

“Finding pesticides from flea and tick treatments on common garden birds feathers, and within songbird eggs and chicks, is deeply alarming, especially as the UK faces a growing songbird crisis. As pet owners, we need to have confidence that we can protect our pets and own health, without harming wildlife.

The government must urgently assess the environmental impact of spot-on flea and tick products and strengthen regulation. An effective first step would be to make them prescription-only, ensuring access is maintained but with proper veterinary guidance. A label on a box isn’t enough. We need informed conversations between vets and pet owners to protect pets, homes and the environment.”

Craig Macadam, Co-Leader & Director of Conservation, Buglife, said:

“Freshwater life is under threat, and veterinary medicines are contributing. Toxic chemicals are widely used on pets regardless of parasite presence, leaving residues that pollute homes and wash into rivers and streams at levels deadly to aquatic invertebrates. That must stop, the evidence is clear and it has been known for far too long. We need rapid, strong 5 measures to prevent the most toxic chemicals from entering waterways before the harm becomes permanent. Ensuring that only qualified professionals can administer these pesticides is a vital step to maintain animal welfare and cause minimal harm to the planet.” 

Dr Janina Gray, Head of Science & Policy, WildFish added:

“Veterinary medicines are quietly contaminating our rivers with potent chemicals designed to kill insects and other invertebrates, yet their environmental impact remains dangerously under-monitored and under-regulated. Without stronger regulations and routine monitoring, we risk steadily degrading the freshwater ecosystems that sustain wild fish populations and wider biodiversity. “Government ministers are now reportedly considering a ban on over-the-counter flea treatments for pets. If implemented, this would be a welcome first step towards tackling the growing threat posed by veterinary medicines and their potentially devastating impact on wildlife.”

Interviews are available with:

1. Professor Dave Goulson, Professor of Biology at the University of Sussex, leading expert on insect ecology and signatory to the letter. Please contact pr@songbird-survival.org.uk  

2. Dr Cannelle Tassin de Montaigu on the new research on fipronil and imidacloprid and wild bird feathers and nests/offspring. Please contact pr@songbird-survival.org.uk

3. SongBird Survival - Sue Morgan, CEO  and Emma Phipps, Scientific Research and Impact Manager. Please contact pr@songbird-survival.org.uk

4. Buglife - Please contact Nikki.Banfield@buglife.org.uk

5. WildFish - Dr Janina Gray, Head of Science & Policy, WildFish. Please contact paul@wildfish.org

Read the open letter.

The University of Sussex new studies are available: Transfer of veterinary parasiticides from the fur lining bird's nest to eggs and chicks and Ubiquitous presence of pesticides in feathers of common UK birds

WildFish report on the problem of veterinary medicines in the aquatic environment

Buglife report on the effects of veterinary tick and flea treatments on freshwater invertebrates and ecosystems

The British Veterinary Association has issued guidance to vets to avoid blanket treatment, instead risk assessing use of parasiticides for individual animals, and where possible and reasonable, avoid prescribing topical products for pets which are likely to swim or be bathed. Their policy is available here.  

Recent government updates on their roadmap to address fipronil and imidacloprid in the environment can be seen here, and an update on a review of distribution categories here.

‍