River pollutants linked to male infertility

The rise in male infertility and the decline in human sperm counts could be linked with chemicals in the environment known as anti-androgens which block the action of the male sex-hormone testosterone, a study has found.

Scientists have identified a group of river pollutants that are able to stop testosterone from working. These anti-androgens have been linked with the feminisation of fish in British rivers and could be affecting the development of male reproductive organs in humans, it found.

The study has established a link between anti-androgens released into rivers from sewage outflows and abnormalities in wild fish where males develop female reproductive organs. It is the first time that anti-androgens and hermaphrodite fish have been linked in this way.

Until now it was thought another class of chemicals, which mimic the effect of the female sex-hormone oestrogen, were responsible for sex-changed fish. However the latest study indicates that the cause may be the result of a rather more complicated interaction taking place between different pollutants.

Dr Susan Jobling of Brunel University, is one of the authors of the study carried out with colleagues from Exeter and Reading universities and the Centre of Ecology and Hydrology. She said: "We have identified a new group of chemicals in our study on fish, but we do not know where they are coming from or what they are. We've only been able to measure their testosterone-blocking potential."

For the study, published in thejournal Environmental Health Perspectives, the scientists analysed anti-androgenic activity in samples of river water taken near 30 sewage outflows. They were able to demonstratestatistically that this activity could be linked with hermaphrodite fish found in the same rivers.

Dr Jobling said that there are several chemicals in widely-used pharmaceuticals and pesticides that are known to have anti-androgenic activity. They included flutamide and cyproterone, used to treat prostate cancer, and several compounds found in agricultural pesticides.

The scientists detected relatively high levels of anti-androgenic chemicals near sewage outflows – suggesting they came from domestic sources. One possibility is that drugs excreted from the body may end up in rivers. However the scientists have not discounted the idea that anti-androgens may also be seeping into rivers as run-off from agricultural land.

Scientists first detected sex-change fish in British rivers more than 20 years ago. During the same period, medical researchers found that human sperm counts have been falling in several countries over a period of 30 years or more. This has been matched by a corresponding rise in other male reproductive problems, such as the congenital condition testicular dysgenesis, which can affect fertility.

Suggested Topics
Start your day with The Independent, sign up for daily news emails
ebooksAn unforgettable anthology of contemporary reportage
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating

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

iJobs Job Widget
iJobs General

Recruitment Genius: Business Development Manager / Sales - OTE £45,000

£35000 - £45000 per annum: Recruitment Genius: This company is a solutions / s...

Recruitment Genius: Sales Executive - OTE £45,000

£18000 - £45000 per annum: Recruitment Genius: A Sales Executive is required t...

Recruitment Genius: Test Development Engineer

£35000 - £40000 per annum: Recruitment Genius: Are you inspired to bring new a...

Recruitment Genius: Trainee Motor Engineer

£14000 - £18000 per annum: Recruitment Genius: This is an exciting opportunity...

Day In a Page

Sepp Blatter resignation: The beginning of Fifa's long road to reform?

Does Blatter's departure mean Fifa will automatically clean up its act?

Don't bet on it, says Tom Peck
Charles Kennedy: The baby of the House who grew into a Lib Dem giant

The baby of the House who grew into a Lib Dem giant

Charles Kennedy was consistently a man of the centre-left, dedicated to social justice, but was also a champion of liberty and an opponent of the nanny-state, says Baroness Williams
Syria civil war: The harrowing testament of a five-year-old victim of this endless conflict

The harrowing testament of a five-year-old victim of Syria's endless civil war

Sahar Qanbar lost her mother and brother as civilians and government soldiers fought side by side after being surrounded by brutal Islamist fighters. Robert Fisk visited her
The future of songwriting: How streaming is changing everything we know about making music

The future of songwriting

How streaming is changing everything we know about making music
William Shemin and Henry Johnson: Jewish and black soldiers receive World War I Medal of Honor amid claims of discrimination

Recognition at long last

Jewish and black soldiers who fought in WWI finally receive medals after claims of discrimination
Beating obesity: The new pacemaker which helps over-eaters

Beating obesity

The new pacemaker which helps over-eaters
9 best women's festival waterproofs

Ready for rain: 9 best women's festival waterproofs

These are the macs to keep your denim dry and your hair frizz-free(ish)
Cycling World Hour Record: Nervous Sir Bradley Wiggins ready for pain as he prepares to go distance

Wiggins worried

Nervous Sir Bradley ready for pain as he prepares to attempt cycling's World Hour Record
Liverpool close in on Milner signing

Liverpool close in on Milner signing

Reds baulk at Christian Benteke £32.5m release clause
On your feet! Spending at least two hours a day standing reduces the risk of heart attacks, cancer and diabetes, according to new research

On your feet!

Spending half the day standing 'reduces risk of heart attacks and cancer'
With scores of surgeries closing, what hope is there for the David Cameron's promise of 5,000 more GPs and a 24/7 NHS?

The big NHS question

Why are there so few new GPs when so many want to study medicine?
Big knickers are back: Thongs ain't what they used to be

Thongs ain't what they used to be

Big knickers are back
Thurston Moore interview

Thurston Moore interview

On living in London, Sonic Youth and musical memoirs
In full bloom

In full bloom

Floral print womenswear
From leading man to Elephant Man, Bradley Cooper is terrific

From leading man to Elephant Man

Bradley Cooper is terrific