Dr Ceri Lewis
Dr Ceri Lewis

Research on feminised fish is giving rise to new policies and guidelines

Government policy and international guidelines for the testing of chemicals have been informed by research conducted at the University of Exeter.

Charles Tyler, Professor of Environmental Biology and Academic Lead in Biosciences, has been investigating the effects of endocrine disrupting chemicals (EDCs) on aquatic ecosystems for more than two decades. Tyler and his colleagues have shown that EDCs, which have the ability to mimic hormones, are concentrated in the effluent of sewage treatment works that are discharged widely into our UK rivers. Some of these chemicals are estrogenic to fish – causing males to produce female proteins and develop eggs in their testes. These estrogenic effects can be detrimental to the fertility of wild fish. The body of evidence that Tyler and his colleagues have developed on EDCs has helped trigger action from government and has been instrumental in influencing new policies and guidelines at both national and international levels.

“Charles’ early studies on the feminising effects of endocrine disrupting chemicals in fish helped set the national baseline and defined the issue,” said Dr Mike Roberts from the Department of Environment, Fisheries and Rural Affairs (Defra). “This subsequently led to the demonstration programme with the water industry to assess how estrogenic substances can be prevented from entering sewage effluent or removed from the effluent, which helped us look at different mitigation strategies and the cost of implementing those at a national level. It also informed our approach to implementing the Water Framework Directive as it set the evidence baseline against which we could objectively assess Commission proposals.”

The National Endocrine Disruption Demonstration Programme was a £40 million project funded by the Environment Agency and the water industry and managed by UK Water Industry Research. The first phase of the programme, completed and reported in 2009, produced extensive data regarding the occurrence, treatment and release of various EDCs from conventional wastewater treatment works.

At an international level, Tyler’s research has influenced and informed guidelines for the testing of chemicals that have been developed by the Organization for Economic Cooperation and Development. It has also provided evidence in reports by the World Health Organization and the United Nations Environment Programme, who work together on campaigns to address the adverse health effects of chemicals on humans and wildlife.

Tyler’s research has had such a far-reaching impact largely because of his active participation in expert panels, authoring of government reports and acting as an advisor to government. Tyler’s research has been funded by government agencies, research councils and industry. His earliest research was funded by Defra, the Centre for the Environment and Fisheries Advisory Services, and the Natural Environment Research Council (NERC).

“NERC have played a fundamental role in supporting our research on endocrine disruption,” said Tyler. “They’ve helped develop us to establish a paradigm shift in terms of how we think about chemicals and their environmental impacts. We have moved away from thinking only about overt toxicity of chemicals and now consider their more subtle interactions in the body , that can nevertheless  have significant detrimental effects on both individuals and populations.”

Current work by Tyler and his team, which is also funded by NERC, is applying genomic techniques to assess how EDCs impact on the genetics of wild fish populations and assess their ability to adapt to these pollutants to help understand population resilience.