New research reveals widespread contamination of English rivers with pesticides commonly used as flea treatments

New research reveals widespread contamination of English rivers with pesticides commonly used as flea treatments - University of Sussex

Researchers at the University of Sussex have found widespread contamination of English rivers with two neurotoxic pesticides commonly used in veterinary flea products: fipronil and the neonicotinoid imidacloprid. The concentrations found often far exceeded accepted safe limits.

These chemicals are banned for agricultural use due to the adverse environmental effects, but there is minimal environmental risk assessment for pesticides used on domestic cats and dogs. This is due to the assumption that there are likely to be fewer environmental impacts due to the amount of product used.

But there is growing concern that this assumption may be incorrect. To investigate this, Professor Dave Goulson and Rosemary Perkins from the University of Sussex analysed data gathered by the Environment Agency in English waterways between 2016-18. They found that fipronil was detected in 98% of freshwater samples, and imidacloprid in 66%.

Rosemary Perkins, a PhD student at Sussex and a qualified vet, said: “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.”

According to the Veterinary Medicines Directorate (VMD), who funded the research, there are 66 licensed veterinary products containing fipronil in the UK, and 21 containing imidacloprid, either alone or in combination with other parasiticides. These include spot-on solutions, topical sprays and collars impregnated with the active ingredient.