Testosterone-blocking chemicals have been found in UK rivers for the first time in new research that strengthens the link between water pollution and rising male fertility problems.
Louise Gray, Environment Correspondent Jan 2009
Anti-androgens, that are found in a number of medicines including cancer treatments and pesticides used in agriculture, were found in 30 rivers across England.
The group of chemicals can block the male hormone and therefore reduce male fertility.
Scientists found male fish are already being affected and warned that it could also be contributing to a reduction in human sperm counts, that have been falling in the last fifty years.
In the past the contraceptive pill has been blamed for “feminising” male fish but levels would have to be extremely high to affect humans.
However anti-androgens have been proven to affect humans in small measures and provide a much stronger link between river pollution and male fertility.
The three year study by Brunel University, the Universities of Exeter and Reading and the Centre for Ecology and Hydrology looked at more than 1,000 fish in rivers across the UK.
Previous studies have already shown that the female sex hormone oestrogen is causing the feminisation of fish and in some cases can lead to male fish changing sex.
The chemical, found in the contraceptive pill and some industrial chemicals, enters rivers via sewage works.
The new study shows that anti-androgens are also causing male fertility problems in a “double whammy” for the fish.
Senior author Professor Charles Tyler of the University of Exeter said the study showed that a much wider range of chemicals than previously thought could be affecting male wildlife and human health.
“Our research shows that a much wider range of chemicals than we previously thought is leading to hormone disruption in fish.
This means that the pollutants causing these problems are likely to be coming from a wide variety of sources.
Our findings also strengthen the argument for the cocktail of chemicals in our water leading to hormone disruption in fish, and contributing to the rise in male reproductive problems.
There are likely to be many reasons behind the rise in male fertility problems in humans, but these findings could reveal one, previously unknown, factor.”
Prof Tyler said there was a lack of evidence to prove a small amount of oestrogen found in river water could affect human fertility, however studies on rats and mice have shown a small amount of anti-androgens can affect male fertility in mammals.
“There is good evidence for more problems in male reproductivty in human males in the last fifty or sixty years,” he said. “The anti-androgens are possibly a contributing factor.”
The study will now concentrate on where the anti-androgens are coming from and the affect on human health.
Lead author on the research paper Dr Susan Jobling at Brunel University’s Institute for the Environment, said the group would be working with regulators like the Environment Agency to consider whether levels of the pollutant need to be controlled in order to protect health.
She said: “We have identified a new group of chemicals in our study on fish, but do not know where they are coming from. A principal aim of our work is now to identify the source of these pollutants and work with regulators and relevant industry to test the effects of a mixture of these chemicals and the already known environmental estrogens and help protect environmental health.”