Toxic pesticides from pet flea treatments and agricultural fungicides have been detected for the first time in two English rivers, raising concerns over threats to aquatic ecosystems.
Helena Horton reports for The Guardian.
In short:
- Researchers found high levels of the pesticide fipronil, used in flea treatments for dogs, in the River Tone and River Wensum. The chemical likely enters waterways when treated dogs swim and is known to harm aquatic life.
- The fungicide propiconazole, commonly used in agriculture, was also found at high concentrations and is associated with health problems in fish.
- Highly toxic neonicotinoid pesticides, dangerous even at low levels, exceeded chronic safety thresholds at a third of sampling sites, threatening invertebrate populations.
Key quote:
“...our research has highlighted that these pesticides are now present in English rivers and could potentially pose threats to the local wildlife.”
— Dr. Christopher Vane, head of organic chemistry, British Geological Survey
Why this matters:
Many people don’t realize that flea treatments applied to pets or pesticides sprayed on crops can wash into rivers and linger in sediments, harming fish, insects, and other aquatic species. Chemicals like neonicotinoids, fipronil, and propiconazole may be used with good intentions — like protecting pets or boosting food production — but they can persist in waterways and quietly damage delicate ecosystems. River invertebrates, often unseen, are the foundation of aquatic food chains and vital to water quality. Their decline can signal broader environmental degradation. As more evidence links household and farming practices to water pollution, scientists are urging closer scrutiny and advising oral flea treatments over topical preventive treatments.
Learn more: Overuse of flea treatments threatens UK wildlife, scientist warns
