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A new British study strengthens the link between water pollution and rising male fertility problems.
The study shows for the first time how a group of testosterone-blocking chemicals is finding its way into UK rivers, affecting wildlife and potentially humans, the authors wrote in a statement.
The study identified a new group of chemicals that act as ‘anti-androgens’. (Anti-androgens’ inhibit the function of the male hormone testosterone - thus reducing male fertility.)
Some of these anti-androgens’ are contained in medicines, including cancer treatments, pharmaceutical treatments, and pesticides used in agriculture.
Feminising male fish
The research suggests that when they get into the water system, these chemicals may play a pivotal role in causing feminising effects in male fish.
This follows on earlier research by the same teams from Brunel University and the University of Exeter that showed how female sex hormones (oestrogens), and chemicals that mimic oestrogens, are leading to ‘feminisation’ of male fish.
Found in some industrial chemicals and the contraceptive pill, these substances enter rivers via sewage treatment works. This causes reproductive problems by reducing fish breeding capability and, in some cases, can lead to male fish changing sex.
May apply to humans
Other studies have also suggested that there may be a link between this phenomenon and the increase in human male fertility problems caused by testicular dysgenesis syndrome, the authors wrote.
Until now, this link lacked credence because the list of suspects causing effects in fish was limited to oestrogenic chemicals whilst testicular dysgenesis is known to be caused by exposure to a range of anti-androgens.
“The new research findings illustrate the complexities in unravelling chemical causes of adverse health effects in wildlife populations and re-open the possibility of a human – wildlife connection, in which effects seen in wild fish and in humans are caused by similar combinations of chemicals," said Lead author Dr Susan Jobling of Brunel University’s Institute for the Environment.
"We have identified a new group of chemicals in our study on fish, but do not know where they are coming from," she said. "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 oestrogens.”
”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," said Professor Charles Tyler of the University of Exeter.
" 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,” he said.
The research is published in the journal Environmental Health Perspectives.
(EurekAlert, January 2009)
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