WildFish joins call for government to address levels of flea and tick treatment chemicals in the environment

Today, WildFish has joined environmentalists, academics and veterinary professionals in writing an open letter to the Environment Minister, Baroness Hayman of Ullock, to warn 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 these two pesticides 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. 

Dr Janina Gray, Head of Science & Policy, WildFish said: “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.” 

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, which includes the RSPB, Greenpeace, Wildlife Trusts and Friends of the Earth – has signed an open letter coordinated by the charities WildFish, Buglife 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 impacts; and 

• Address systemic failures in the regulation of veterinary medicines and the evaluation of their environmental impacts. 

UK Government ministers are currently investigating whether these products, which can currently be sold anywhere and do not require any professional advice from vets or suitably qualified persons on their use, should be restricted to distribution only by veterinary practitioners or pharmacists. The Government has also said it will launch an education campaign for pet owners on responsible use from spring 2026. 

Dr Janina Gray added: “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.”

WildFish recently published a new report about the impacts of veterinary medicines. Read the full report at the button below: