UK Rivers 'Dogged' By Insecticides?

The UK has around 10 million dogs and 11 million cats. It is estimated that 80% of these companion animals are receiving treatments for fleas. The most commonly used insecticides, for this role, are fipronil and imidacloprid (a neonicotinoid). These chemicals function as nerve agents, blocking tranmission across the synapse. Because they cause environmental damage, farmers are currently banned from using fipronil and imidacloprid on their animals but there is no such restriction on their use to kill fleas in 'pets'. A study by Sussex University determined the concentrations of these highly toxic insecticides in 4000 water samples from 20 rivers ( https://www.theguardian.com/environment/2020/nov/17/pet-flea-treatments-poisoning-rivers-across-england-scientists-find). The scientists were horrified to find that 99% of their samples contained fipronil and imidacloprid, at concentrations approaching 40 times that of the safety limit. These nerve agents will poison the water insects (like caddis flies and Mayflies) on which fish and some water birds ultimately depend. They conclude that it is pet flea treatment that is contaminating the rivers. There is, at least, the possibility that some farmers (and other breeders of animals near rivers) are illegally continuing to use these agents (there was resistance to the banning of neonicotinoids in farming circles). 'Policing' this kind of pollution is currently very difficult in England due to cutbacks.