Drugs in water

A study from

, in West London, has revealed that the combined effects of a cocktail of chemicals that act as oestrogens - such as the contraceptive pill, toiletries, household cleaning fluids and fertilizers - could affect our waterways to a far greater extent than previously thought.

Oestrogenic chemicals are believed to impact the fertility, reproduction and gender of aquatic life, and also have the potential to affect reproductive parameters in humans. The research highlights the shortcomings associated with current pollution risk assessment, which is based on assessment of each single chemical’s risk, and calls into question the need for a wholesale re-assessment of the current EU regulation on acceptable chemical levels.

The study, which involved a European team of research partners led by Professor John Sumpter of the Institute for the Environment at Brunel University, investigated the effect of a group of oestrogenic chemicals that have been associated with adverse reproductive effects in aquatic organisms, using freshwater minnows as a test species.

Currently, chemical levels are predicted and assessed by evaluating each chemical’s risk individually. However, the research found that the response to the cocktail was far greater than to each single chemical.

"These results are a real cause for concern. The existing EU legislation is based on the regulation of individual chemicals, however this is not an accurate representation of real life. In reality, there is a cocktail of chemicals in our fresh water. While a safety factor of around 10 is usually employed when estimating the potential risk of chemicals when they interact, our research shows that this may not be enough. Put simply, we may need to consider tougher safety margins to fully protect wildlife and humans," said Professor Sumpter.

Sumpter added that the study "purely evaluated groups of chemicals which act in a similar fashion". More research is needed to fully understand the risks involved when chemicals which react differently are mixed together – and what influence that will have on both the aquatic environment and those drinking the water.

"This research raises the question of whether groups of chemicals which are known to cause thyroid problems, or which have been associated with carcinogenic effects, could behave in the same way, proving more of a risk than we think," he said.

Oestrogenic chemicals found in sewage, which ends up in surface waters, are the by-product of a large variety of products such as the contraceptive pill, toiletries, household cleaning fluids and fertilizers. Many of these chemicals are very slow to break down, remaining in water for considerable periods of time. The study investigated the effects of five specific oestrogenic chemicals in freshwater minnows, but the combined effects reported in this study are likely to occur in all classes of vertebrate, possibly even humans.