Scientists' concern over combinations of pesticides found in River Otter

PUBLISHED: 12:46 05 July 2018 | UPDATED: 10:11 09 July 2018

Dr Jorge Casado, lead researcher of the pesticide project, taking a sample from the River Exe

Dr Jorge Casado, lead researcher of the pesticide project, taking a sample from the River Exe

David Santillo

Scientists have found traces of pesticides banned in the UK and EU in the River Otter, along with a number of other agricultural chemicals which could, in combination, harm the environment

Agricultural pesticides which have been withdrawn from use in the UK are still present in the River Otter.

Scientists from Exeter University also found a large number of other pesticides and fertilisers in the water which they believe could, in combination, have a harmful effect on plants and wildlife.

Their tests were carried out using a new technique they developed themselves to detect chemicals at very low concentrations, which would not have been picked up by other methods. They also tested water samples from the River Tale, a tributary of the Otter, the Exe and the Culm, and found a large number of pesticides, albeit in low concentration, in all of them.

The research team, from the Greenpeace Research Laboratories, will be passing on their findings to the Environment Agency. Their paper has already been published in scientific journals.

Principal scientist Dr Paul Johnston said: “We are tremendously excited by this work. We will be flagging it up to a number of regulatory authorities, although the Environment Agency will probably come across it through their own surveillance.”

He said the traces of herbicides, fungicides and fertilisers came from agricultural run-off, and that the presence of the banned chemicals indicates that the soil still contains residues from their historical use. And he believes that further research is needed on how all the pesticides could, in certain combinations, affect the ecosystem.

“No-one has a real grip on the toxicology of these mixtures, and we don’t know if there is a synergistic effect making the situation worse,” he said. “They are regulated substance by substance, but that’s not how they occur in the environment. We are finding a variety of pesticides of all persuasions and we don’t know how they behave in combination.”

A spokesman for the NFU in Devon said: “The agricultural industry has been working hard to minimise its impact on watercourses and the UK has one of the most robust regulatory and monitoring systems for pesticide in the world. The overall amount used in the UK has halved since 1990 and this study would seem to confirm that, as the amounts of pesticide found are absolutely minute and many orders of magnitude below the legal minimums specified by the EU.”

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