American Association for the Advancement of Science

Something fishy going on... Antidepressants contaminating rivers make perch antisocial

 

Science Editor, Boston

Drugs used to treat anxiety and depression are contaminating rivers and streams where they are building up in concentrations that can affect the behaviour of wild freshwater fish, scientists have found.

Significant amounts of a benzodiazepine drug called Oxazepam, which is widely used to treat anxiety, are being flushed into rivers from sewage works. The concentrations are too low to be considered a health risk to humans but a study has shown they can still affect fish.

Benzodiazepines, such as Valium, are one of the most widely prescribed groups of drugs. They can be excreted from the body intact and persist in the treated effluent water released from sewage works into rivers, scientists said.

A study carried out in Sweden found that the relatively low concentrations of benzodiazepines commonly found in rivers throughout Europe, including Britain, can significantly affect the behaviour of the European perch.

The scientists found that perch exposed to extremely small concentrations of Oxazepam, as low as a fraction of a microgram per litre of water, were less sociable, bolder and ate faster than fish that were not exposed to the drug.

The scientists believe the subtle behavioral changes seen under experimental conditions indicate how the wider freshwater ecology could be affected by this kind of hidden environmental pollution.

They said that pharmaceutical compounds released into the aquatic environment might pose a greater problem than hitherto realised and that more should be done to degrade the chemicals before being released in the treated effluent water from sewage works.

“The solution to this problem isn't to stop medicating people who are ill but to try to develop sewage-treatment plants that can capture environmentally hazardous drugs,” said Jerker Fick of Umeå University in Sweden, who was part of the team.

“These drugs are not toxic or harmful in small doses, and are used to treat patients for therapeutic reasons. So there has not been that much research into what it does when it gets into our waterways,” Dr Fick said.

A survey of the River Fyris in Sweden, which receives wastewater effluent from the city of Uppsala, found concentrations of oxazepam of around 0.58 micrograms per litre. “These concentrations are comparable to hose of benzodiazepines reported in other European and American waters,” the scientists report in the journal Science.

It was one of 21 pharmaceuticals found in the water sampled by the researchers that have a similar effect to Oxazepam, the scientists said.

Tomas Brodin of Umea, the lead author of the study, told the American Association for the Advancement of Science meeting in Boston that when wild perch were exposed to similar concentrations they exhibited subtle but distinct changes to their natural behaviour.

“Perch that were exposed to Oxazepam lost interest in hanging out with the group, and some even stayed as far away from the group as possible,” Dr  Brodin said.

“While alone, fish that were exposed to Oxazepam dared to leave safe refuge and enter novel, potentially dangerous areas. In contrast, unexposed fish stayed hidden in their refuge. The exposed fish seemed much less stressed and scared, behaving calmer and bolder,” he said.

Fish exposed to the drug ate faster than non-exposed fish. This could affect the wider ecology because more voracious perch would eat more of the zooplankton that might otherwise prevent algal blooms, Dr Fick said.

'We found distinct behavioural changes in the perch, even at low levels of exposure. The changes can be seen as both beneficial or detrimental depending on the ecology,“ he said.

”The fish became bolder and fed faster, which is a good thing if there are no predators around, but could be risky if there are,“ be added.

”It could also have a knock-on effect on the surrounding environment. If the fish eat more zooplankton, then there is less in the water. Zooplankton eat algae, so without them there could be algae blooms.“

Start your day with The Independent, sign up for daily news emails
ebooks
ebooksA celebration of British elections
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Senior Digital Marketing Consultant

£28000 - £45000 per annum: Recruitment Genius: A Senior Digital Marketing Cons...

Recruitment Genius: Assistant Stores Keeper

£16640 - £18500 per annum: Recruitment Genius: An Assistant Stores Keeper is r...

Recruitment Genius: Claims Administrator

£16000 - £18500 per annum: Recruitment Genius: This is an excellent opportunit...

Recruitment Genius: Software Developer - C# / ASP.NET / SQL

£17000 - £30000 per annum: Recruitment Genius: Developer required to join a bu...

Day In a Page

Fishing for votes with Nigel Farage: The Ukip leader shows how he can work an audience as he casts his line to the disaffected of Grimsby

Fishing is on Nigel Farage's mind

Ukip leader casts a line to the disaffected
Who is bombing whom in the Middle East? It's amazing they don't all hit each other

Who is bombing whom in the Middle East?

Robert Fisk untangles the countries and factions
China's influence on fashion: At the top of the game both creatively and commercially

China's influence on fashion

At the top of the game both creatively and commercially
Lord O’Donnell: Former cabinet secretary on the election and life away from the levers of power

The man known as GOD has a reputation for getting the job done

Lord O'Donnell's three principles of rule
Rainbow shades: It's all bright on the night

Rainbow shades

It's all bright on the night
'It was first time I had ever tasted chocolate. I kept a piece, and when Amsterdam was liberated, I gave it to the first Allied soldier I saw'

Bread from heaven

Dutch survivors thank RAF for World War II drop that saved millions
Britain will be 'run for the wealthy and powerful' if Tories retain power - Labour

How 'the Axe' helped Labour

UK will be 'run for the wealthy and powerful' if Tories retain power
Rare and exclusive video shows the horrific price paid by activists for challenging the rule of jihadist extremists in Syria

The price to be paid for challenging the rule of extremists

A revolution now 'consuming its own children'
Welcome to the world of Megagames

Welcome to the world of Megagames

300 players take part in Watch the Skies! board game in London
'Nymphomaniac' actress reveals what it was really like to star in one of the most explicit films ever

Charlotte Gainsbourg on 'Nymphomaniac'

Starring in one of the most explicit films ever
Robert Fisk in Abu Dhabi: The Emirates' out-of-sight migrant workers helping to build the dream projects of its rulers

Robert Fisk in Abu Dhabi

The Emirates' out-of-sight migrant workers helping to build the dream projects of its rulers
Vince Cable interview: Charging fees for employment tribunals was 'a very bad move'

Vince Cable exclusive interview

Charging fees for employment tribunals was 'a very bad move'
Iwan Rheon interview: Game of Thrones star returns to his Welsh roots to record debut album

Iwan Rheon is returning to his Welsh roots

Rheon is best known for his role as the Bastard of Bolton. It's gruelling playing a sadistic torturer, he tells Craig McLean, but it hasn't stopped him recording an album of Welsh psychedelia
Morne Hardenberg interview: Cameraman for BBC's upcoming show Shark on filming the ocean's most dangerous predator

It's time for my close-up

Meet the man who films great whites for a living
Increasing numbers of homeless people in America keep their mobile phones on the streets

Homeless people keep mobile phones

A homeless person with a smartphone is a common sight in the US. And that's creating a network where the 'hobo' community can share information - and fight stigma - like never before