Pet owners should be banned from buying flea sprays at supermarkets because they contain chemicals which pollute the environment, a parliamentary committee said. She said: 'The overuse of household pet flea and tick treatments is the equivalent of using a sledgehammer to crack a nut. She said although flea treatments can be important in healing pets, over the counter sales need to be banned. 'These flea treatments are among the most toxic chemicals entering our rivers, yet they continue to be sold with little thought for where they end up. 'Pet owners deserve clear, informed advice before using these products so they can understand the potential impact on rivers and wildlife.