More than 100 pesticides and 21 drugs were detected in the 29 waterways analysed in 10 European nations, including the UK. A quarter of the chemicals identified are banned, while half of the streams analysed had at least one pesticide above permitted levels. The researchers said the high number of pesticides and drugs they found meant complex mixtures were present, the impact of which was unknown. Pesticides are acknowledged as one factor in plummeting populations of many insects and the birds that rely on them for food. Insecticides were revealed to be polluting English rivers in 2017.