Chemical cocktail in waterways raises fresh fears

Posted: 7 March 2007

A groundbreaking study by British scientists has revealed that the combined effects of a cocktail of chemicals are affecting UK waterways to a far greater extent than previously thought. Their research unearths evidence that mixtures of chemicals are acting together to affect reproductive processes of fish.

The study by Dr. Jayne Brian and Prof. John Sumpter at Brunel University's Institute for the Environment, investigated the effects of oestrogenic chemicals in fathead minnows. But, the researchers say, the combined effects reported in this study are likely to occur in all classes of vertebrate.

Not only is the combination of estrogenic chemicals negatively impacting the fertility, reproduction and gender of aquatic life, it also has the potential to affect reproductive parameters in humans.

Highlighting the shortcomings associated with current pollution risk assessment (based on assessment of each single chemical'srisk), Prof. Sumpter and Dr Brian say it may be necessary to make a wholesale re-assessment of the current EU regulation on acceptable chemical levels.

Dr Brian explains: "Following our initial study in 2005, we have uncovered clear and unequivocal evidence that combinations of chemicals are a real cause for concern. Our research highlights the risk of population-level effects in the real world, where wildlife may be simultaneously exposed to a number of chemicals."

Important principle

"Existing EU legislation is based on the regulation of individual chemicals," he said. "This is not an accurate representation of real life. In reality, there is a cocktail of chemicals in our fresh water. We need to consider tougher safety margins to fully protect wildlife and humans."

Commenting on the potential risk to humans of a combination of chemical pollutants, Dr Sumpter told this website "we have studied mixtures of estrogenic chemicals, and their effects on reproduction in fish. This is really just a model system; the results could probably apply to any mixture of chemicals, any species, and anyeffect."

"It is the principle that is important. We have shown that a mixture of chemicals can have a serious adverse effect when each individualchemical in that mixture is present at too low a concentration to cause an effect.

"We studied effects of environmentally-realistic mixtures of estrogenic chemicals on reproduction in fish. People are also exposed to mixturesof estrogenic chemicals, and I would expect the principle of our finding (that mixtures can cause adverse effects when each individual chemical does not) to apply to them as well".

Oestrogenic chemicals found in sewage, which ends up in surface waters, are the by-product of a large variety of products such as thecontraceptive 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.

Related link:

Water pollution factfile