COCAINE has been identified in a scenic river immortalised by artist John Constable.

The surprise findings came after a study by King’s College London and Suffolk University, which found a number of illicit drugs, chemicals and pesticides in river wildlife.

The study looked at the exposure of wildlife, such as the freshwater shrimp, to chemicals and the levels of these compounds in the animals.

The team collected samples from sites across Suffolk, including the River Stour which runs through Stratford St Mary, Dedham and Flatford - the birthplace of Constable and the setting for some of his most celebrated paintings.

Cocaine was found in all samples tested.

Other illicit drugs such as ketamine, pesticides and pharmaceuticals were also widespread in the shrimp which were collected.

The main aim of the study had been to search for the presence of pesticides and the tests for pharmaceutical and illegal drugs were secondary.

The cocaine was found in concentrations of between three and five parts per billion and is likely to have passed through users of the drug via the sewer system and into the rivers.

Consumer products, medicines and drugs can end up in rivers after use and comprise thousands of different chemicals which have the potential to cause environmental harm.

Professor Nic Bury from Suffolk University, said: “Whether the presence of cocaine in aquatic animals is an issue for Suffolk, or more widespread an occurrence in the UK and abroad, awaits further research.

“Environmental health has attracted much attention from the public due to challenges associated with climate change and microplastic pollution.

“The impact of invisible chemical pollution (such as drugs) on wildlife health needs more focus in the UK as policy can often be informed by studies such as these.”

Conservationist and Dedham Vale Society chairman Charles Clover added: “If this is what is happening in a rural river in Suffolk with very few large towns on it, God only knows what the Thames is full of.

“I suspect this is a low level, not at all a level of concern, but it must be in some rivers, somewhere.”

Dr Leon Barron from King’s College London, added: “Such regular occurrence of illicit drugs in wildlife was surprising.

“We might expect to see these in urban areas such as London, but not in smaller and more rural catchments.”

The study did not include Essex rivers.

“The presence of pesticides which have long been banned in the UK also poses a particular challenge as the sources of these remain unclear” Dr Barron added.

Lead author, Dr Thomas Miller from King’s College London said: “Although concentrations were low, we were able to identify compounds that might be of concern to the environment and crucially, which might pose a risk to wildlife.

“As part of our ongoing work, we found that the most frequently detected compounds were illicit drugs, including cocaine and ketamine and a banned pesticide, fenuron. Although for many of these, the potential for any effect is likely to be low.”

Presence of fenuron was likely to be caused by old traces of the chemical that have remained in soil close to the rivers.