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New research strengthens the link between water pollution and rising male fertility problems.
The study, by Brunel University, the Universities of Exeter and Reading and the Centre for Ecology & Hydrology, 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 research was supported by the Natural Environment Research Council and is now published in the journal Environmental Health Perspectives.
The study identified a new group of chemicals that act as ‘anti-androgens.’
This means that they inhibit the function of the male hormone, testosterone, reducing male fertility. Some of these are contained in medicines, including cancer treatments, pharmaceutical treatments, and pesticides used in agriculture.
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.
Earlier research by Brunel University and the University of Exeter has shown how female sex hormones (estrogens), and chemicals that mimic estrogens, are leading to ‘feminisation’ of male fish.
Found in some industrial chemicals and the contraceptive pill, they 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.
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. Until now, this link lacked credence because the
list of suspects causing effects in fish was limited to estrogenic
chemicals whilst testicular dysgenesis is known to be caused by
exposure to a range of anti-androgens.
Lead author on the research paper, Dr Susan Jobling at Brunel
University’s Institute for the Environment, said of the study's
findings: “We have been working intensively in this field for over ten
years. The new research findings illustrate the complexities in
unravelling chemical causation 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.
“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.”
Senior author Professor Charles Tyler of the University of Exeter said:
“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.”
In making their findings the scientists studied over 1000 fish sampled from 30 rivers in various parts of England.
The research took more than three years to complete and was conducted
by the University of Exeter, Brunel University, University of Reading
and the Centre for Ecology & Hydrology.
The
research team is now focusing on identifying the source of
anti-androgenic chemicals, as well as continuing to study their impact
on reproductive health in wildlife and humans.
[19January2009 www.LifeSiteNews.com]
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