EA presss release:

Oestrogenic hormones are affecting the reproductive ability of male fish, which could put the sustainability of fish populations in rivers in the North West of England at risk, the Environment Agency said today.

Publishing the most recent scientific research on hormone disruption in fish in the UK, the Agency said that oestrogenic steroids - natural and synthetic hormones in sewage effluent - have been shown to be more potent than previously thought, with the synthetic steroid 17a ethinyloestradiol (the contraceptive pill), showing effects in fish at concentrations below 1 nanogram per litre (a thousand millionth of a gram).

Evidence of harm to fish, including male fish developing eggs within their reproductive organs, has now been shown in some cases to reduce their ability to reproduce. This "feminisation" of male fish is of sufficient concern, the Agency said, to develop a risk management strategy and require serious consideration of changes to sewage treatment technologies.

The Agency's Head of Chemicals Policy, Steve Killeen said: "While we do not know what impact oestrogenic substances might have on the long term viability of some wild fish populations, we believe there is now sufficient evidence of harm to fish to develop a risk management strategy for oestrogens in sewage effluent.

"The strategy may require changes in sewage treatment practices, possibly meaning the development of new technologies for some sewage treatment plants. However, not all fish populations will be affected so action has to be carefully targeted according to risk."

Over the next two years, the Environment Agency will work to identify which sewage treatment works (STWs) in England and Wales should be considered for action. Preliminary risk assessments are already underway to determine which STWs are likely to discharge oestrogens at levels that could affect fish, but more work is needed to refine these estimates.

The Agency is now looking to the water industry to investigate effective sewage treatment technologies for the removal of priority oestrogens, including the natural and synthetic steroid hormones.

The Environment Agency wants to see a collaborative programme, involving the water industry and other stakeholders, to develop a common approach to assessing the impact of oestrogenic effluents, identify priority sewage treatment works and to evaluate the effectiveness, costs and benefits of treatment options.

Steve Killeen said: "We need to be confident that potentially major investment in treatment options will be effective. The environmental benefit - the degree to which damage to fish can be reduced - will have to justify the cost."

The research published today was undertaken by scientists at Brunel University and Exeter University, and funded by the Environment Agency, the Department for Environment, Food and Rural Affairs and the Natural Environment Research Council.

Research involved studying wild populations of the coarse fish species roach and gudgeon in 10 river catchments in England and Wales receiving effluent from sewage treatment works. The study confirmed the presence of feminised male fish in both species, and scientists believe it likely that similar species will also be affected.

Researchers found that the reproductive capability in moderate to severe intersex male roach was reduced, and that one third of the fish failed to produce sperm - even after spawning hormone treatment. Experiments also showed that sewage effluents induced some of the oestregenic effects seen in wild fish, establishing a firm 'cause and effect' relationship. Spawning rates will depend on local risks which are now being characterised for England and Wales.

The research conducted focused on feminising effects in fish, their causes and consequences and did not generate any information relevant to public health.