Current Affairs The fate of crayfish in the Vltava sparks concern about male fertility

Numerous scientific studies suggest that heightened levels of the female hormone estrogen in some European rivers are changing the sex of male fish or at the very least harming their reproductive ability. A recently concluded study on crayfish in the Vltava river indicates that the problem is quite serious. Ludek Blaha is a natural scientist from Charles University:

"It is known that such a sex change - i.e. from male to female - occurs naturally in some species but in the population of crayfish which we have monitored long-term it would occur naturally in two to three percent. We found that it occurred in twenty to twenty-five percent."

Publication of the study has fuelled the debate on the possible risks of hormone-pollution to animal and human health. There is concern that estrogen finds its way into our drinking water or is recycled in the food chain and may be having a negative impact on male fertility. Although statistics show a decrease in male fertility, such a link has not been scientifically proven. However Miroslav Suta, a specialist on human health and the environment, says that the danger is far closer to home. A broad range of chemical substances - primarily phthalates - which are found in our immediate environment, articles of daily use and even children's toys - have a similarly detrimental effect.

Miroslav Suta "It was ascertained that phthalates act similarly as the female hormone estrogen. Tests on animals who had traces of phthalates added to their food did not show any immediate ill-affects but their male offspring had breeding problems - poorly developed organs and a lower sperm count."

The effects of so called "endocrine disrupting chemicals" - ie. chemicals which effect the body's hormonal balance - have been the object of study for only ten years but the results are being taken very seriously. Miroslav Suta says the European Union is now working on a common policy which would minimize the risks for public health.

"At present the EU is trying to curb the use of phthalates in medical equipment - for instance in drips. They are already banned in toys for children under age three. There is also a big debate around brominated-flame-retardants which are considered equally harmful. Some chemicals have already been banned, and there is an ongoing debate about others. The EU is now working on a common chemicals policy and has a new chemicals regulation body called REACH which will conduct more intensive research into various production chemicals and push for a ban or restrictions on their use."

Research workers have already found many cases of chemicals damaging human health. In Canada women who ate a lot of fresh-water fish during pregnancy from lakes which were found to contain higher levels of polychlorinated biphenyls had children with a lower than average IQ and concentration problems because the chemical affected their thyroid gland. The danger of chemicals used in production is that their effects are slow to surface and may not be obvious at first sight. Research teams around the world are now trying to ascertain which of them could cause serious long-term damage and it will then be up to individual governments to adopt norms which would protect human health and the environment while maintaining competitiveness.