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past feature
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A
Fishy Business
Scientists at the University of the West
of England (UWE) have measured the
concentration of the female sex hormone
oestrogen in river water by gas
chromatography-negative chemical
ionisation mass spectrometry.
Small quantities of oestrogens are
excreted from the body and enter the
sewage system. Although these chemicals
seem to be largely removed in sewage
treatment, it seems that minute quantities
remain and can enter rivers. These very
low levels of oestrogens have been shown
to be responsible for signs of sex changes
in male fish in rivers to which sewage is
discharged.
Beyond the appearance of female
characteristics in fish, there is concern
that such oestrogen levels may have a
detrimental effect on human male fertility
by being recycled back into the human food
chain. There has also been a link to an
increase in testicular cancer.
The project is a collaboration between UWE
and the Environment Agency, and involves
taking samples of water from the Thames in
London. The techniques developed can also
distinguish whether the hormones present
are naturally occurring or result from use
of the contraceptive pill. "We discovered
that the largest concentrations in the
River Thames are of naturally produced
oestrogens" says Project leader Dr David
McCalley. "We can now detect quantities of
oestrogens down to levels equivalent to a
pinch of sugar in an Olympic swimming
pool. Our method is sensitive enough to
allow direct chemical measurements of
oestrogens in rivers, rather than
measuring them indirectly through their
biological effects."
The samples were taken from the lower
reaches of the Thames. Dr McCalley
stressed that the water in the higher
reaches of the river, from where it is
extracted for drinking purposes, was
likely to be cleaner. "Our detection
method could certainly be used to monitor
levels in drinking water. At present there
are no standards laid down for what levels
of oestrogen are permissible in water, but
now we have developed a way to monitor
these levels it might lead to standards
being set."
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