Toxic chemicals in pet flea treatments harming wildlife, UK study warns

Toxic chemicals found in pet flea treatment are devastating wildlife in rivers, parks and special conservation areas and the government should take urgent action to limit their use, according to a study.

Chemicals that are banned for use as pesticides but still used in flea treatments are causing potentially irreversible harm to aquatic life as well as decimating birds and pollinators, according to the study published on Thursday.

It found that flea treatment chemicals fipronil and imidacloprid have also been implicated in lower cognitive and adaptive scores in children with autism and was ranked by the Environment Agency as being the chemical with the highest risk to human health in English waters.

The assessment by ecologist Matt Shardlow, who carried out one of the first studies into the impact of flea treatments nine years ago, says urgent action is needed to prevent these chemicals doing more damage.

“The more you look at this, the worse it gets,” said Shardlow from the Wildlife and Countryside Link. “The level of new alarming information showing the scale of damage that is being done by these chemicals is stark.”

Last month the Guardian reported on calls for restrictions on pet flea treatments after research found songbird feathers were widely contaminated with chemicals that can damage their brains and kill unborn chicks. A previous study found chicks were being killed by high levels of pesticides in the pet fur used by their parents to line their nests.

The analysis found irreparable damage may already have occurred to rivers, sites of special scientific interest and National Parks. It highlighted the Broads in Norfolk, where all the main rivers entering the park are heavily contaminated with flea treatment toxins, and where Natural England is concerned about a 90% decline in dragonfly numbers.

It found that average levels of fipronil and imidacloprid were high enough in English rivers to “reduce aquatic life”. In a fifth of cases levels were found to be sufficient to cause a 30% reduction in “associated bird populations”.

“We are seeing not just impacts in rivers but in public parks where dandelions were so heavily polluted that it is likely to harm caterpillars and pollinators,” said Shardlow.