Levels of illegal drugs high enough to harm wildlife have been found in the river running through the site of Glastonbury Festival.
During the festival levels of MDMA and cocaine in the water were so high they could affect rare populations of eels further downstream, researchers discovered.
They have urged revellers to use the official toilets provided by organisers as it is thought the drugs can enter nearby rivers as a result of public urination.
Dan Aberg, a Masters student at the School of Natural Sciences at Bangor University and Dr Daniel Chaplin from the Centre for Environmental Biotechnology (CEB) measured levels of illicit drugs before, during and after the Glastonbury Festival in 2019, when it was last held.
Samples were taken from the Whitelake River both upstream and downstream of the site of the festival.
The researchers found MDMA concentrations quadrupled the week after the festival, suggesting the long-term release of drugs from the site.
They also discovered that concentrations of cocaine rose to levels known to affect the lifecycle of European eels, which are a protected species.
Mr Aberg said: “Illicit drug contamination from public urination happens at every music festival.
“The level of release is unknown, but festivals undoubtedly are an annual source of illicit drug release.”
He added: “Unfortunately, Glastonbury Festival’s close proximity to a river results in any drugs released by festival attendees having little time to degrade in the soil before entering the fragile freshwater ecosystem.”
The researchers suggested that studies should be conducted into possible treatment via environmentally friendly methods such as constructed treatment wetlands.
Dr Christian Dunn, from Bangor University, said: “Our main concern is the environmental impact. This study identifies that drugs are being released at levels high enough to disrupt the lifecycle of the European eel, potentially derailing conservation efforts to protect this endangered species.
“Education is essential for environmental issues, just as people have been made aware of the problems of plastic pollution, and Glastonbury have made great efforts to become plastic-free, we also need to raise awareness around drug and pharmaceutical waste – it is a hidden, worryingly-understudied yet potentially devastating pollutant.”
A spokesman for Glastonbury Festival said: “Protecting our local streams and wildlife is of paramount importance to us at Glastonbury Festival and we have a thorough and successful waterways sampling regime in place during each Festival, as agreed with the Environment Agency. There were no concerns raised by the Environment Agency following Glastonbury 2019.
“We are aware that the biggest threat to our waterways – and the wildlife for which they provide a habitat – comes from festivalgoers urinating on the land.
“This is something we have worked hard to reduce in recent years through a number of campaigns, with measurable success. Peeing on the land is something we will continue to strongly discourage at future festivals. We also do not condone the use of illegal drugs at Glastonbury.
“We are keen to see full details of this new research, and would be very happy to work with the researchers to understand their results and recommendations.”