Insecticide pollution in a Tunbridge Wells waterway has been traced to a sewage treatment works following an investigation by Tonbridge and Malling Friends of the Earth.
The local Friends of the Earth group decided to carry out tests after a report by Buglife, published in December 2017, identified Somerhill stream in Tunbridge Wells as one of a number of waterways polluted with high levels of neonicotinoid pesticides.
Imidacloprid, the chemical found in Somerhill stream, was restricted for most agricultural uses in 2013, and was banned from use in all agricultural fields in 2018 but is still allowed as a pet flea treatment.
Although the source of neonicotinoid pollution in some British rivers has been linked to previous use of these chemicals on farms the most likely source of pollution in the Somerhill Stream is flea pet treatments. The waste water is from a predominantly urban area and washing of pets and their bedding is likely to result in the chemicals appearing in the waste water.
Concerned by the harm caused to their local environment, Nathalie Baron and Anthony Bales from Tonbridge and Malling Friends of the Earth undertook their own investigation over several months, conducting extensive research and field work that culminated in collecting samples from strategic points in November 2018 and sending them to a laboratory for analysis.
The results revealed that the stream continues to be polluted at chronically harmful levels with Imidacloprid (0.192µg/l). More significantly the levels recorded in the outfall from the Tunbridge Wells North Waste Water Treatment Works in Dowding Way were even higher (0.233µg/l) and concentrations were so high that scientific evidence shows they could harm aquatic life over a short time of exposure.
Nathalie Baron of Tonbridge and Malling Friends of the Earth said: "We are extremely concerned by our findings: Imidacloprid pollution poses a significant threat to our local aquatic life. Research in other countries has demonstrated that Waste Water Treatment Plants are releasing dangerous levels of Imidacloprid into waterways. We appreciate that Water Treatment Plants such as Southern Water’s Tunbridge Wells North Waste Water Treatment Works are not currently required by the regulations to test for Imidacloprid contamination. We are therefore calling on the government to take the necessary steps to ensure that Imidacloprid levels are monitored at the water treatment stage and that urgent action is taken to eliminate it from our streams and rivers."
Matt Shardlow CEO of Buglife, and author of the pivotal report on neonicotinoid pollution in freshwater said: “Hats off to Nathalie and Anthony from Tonbridge and Malling Friends of the Earth for revealing the source of this pollution and helping to confirm that pet flea treatments are harming our rivers.
“It is distressing that nothing concrete has been done by the authorities in the 12 months since we published our report and recommended that Imidacloprid flea treatments should be suspended and their pollution of the environment reviewed. Our mayflies, beetles and dragonflies continue to suffer from high levels of insecticides; we hope that Defra will ensure that action is taken soon.”
Until Defra and the Veterinary Medicines Directorate take action the public are being advised by Buglife to:
1. Only use pet flea treatments when necessary.
2. To avoid persistent insecticides such as Imidacloprid and Fipronil.
3. Not to allow pets that have been treated in the previous 3 months to enter water.
4. To destroy bedding used by treated pets, rather than washing it.
5. To wash treated pets in the garden, not the bathroom, and to dispose of any washing water by pouring it onto a low wildlife value lawn.