Research conducted in the Tyler Laboratory at the University of Exeter has identified the widespread disruption of sexual development in roach fish (Rutilus rutilus) in UK rivers. This has subsequently proven that the condition arises as a consequence of exposure to wastewater effluents containing oestrogens. This work has shown that feminised males have a reduced reproductive capability with potential impacts for the sustainability of wild fisheries. The Tyler lab has further identified the causative environmental oestrogens discharged in these waste waters. This work on roach has led to recognition internationally that exposure to endocrine disrupting chemicals (EDCs) can have widespread impacts on the natural environment.
The University of Exeter's Ecotoxicology and Aquatic Biology Research Group is a large, dynamic group studying the effects of environmental pollutants on aquatic wildlife and investigating the basic physiology of fish. Key areas of our ecotoxicology work are endocrine disruption and the biological effects of nanoparticles. Their work on pollutants span studies investigating the mechanisms of effect in individuals to population-level impacts. Long-term exposure effects to environmentally relevant concentrations of pollutants and mixture effects are key themes in this work and reproduction and reproductive behaviour are the major processes studied. A wide range of in vivo and in vitro techniques are employed, including gene arrays and DNA microsatellites. The group has very extensive international collaborations with academic institutions, government bodies and industry and is well funded from a wide range of organisations including, UK Research Councils, The European Union, The Environment Agency, DEFRA, and various industries
Research by the group has demonstrably led to the following impacts:
- £40m of direct investment by DEFRA and the UK Water Industry to remove compounds from the system (National Endocrine Disruption Programme). A National Demonstration Programme managed by UK Water Industry Research (www.ukwir.org.uk) has been undertaken by all 10 water and sewerage companies in England and Wales and the Environment Agency. The first phase of this project has been completed and reported in 2009 (Endocrine Disrupting Chemicals National Demonstration Programme: Assessment of the Performance of WwTW in Removing Oestrogenic Substances, 09/TX/04/16).
- £4.9m per annum of efficiency savings to the UK production industry via Knowledge Transfer Partnership (KTP). The Tyler Laboratory has developed long term collaborative links with industry including AstraZeneca, Syngenta, UK water companies, and a KTP awarded in 2009 with Astra Zeneca (To develop functional genomics biomarkers as effects screens to be used in ecotoxicology for environmental risk assessment and toxicology for human safety assessment)
- £440,000 per annum of potential new regulatory testing, representing the social value of reduced environmental damage. Based on a very low scenario, even a 0.1% change in regulatory costs in this sector relating to testing of residual compounds that feed into water systems would equate to potential impact of £1.1 million to UK companies. This is in line with standard testing costs for adoption of similar regulatory tests. Recognising that Exeter's world leading, but not unique research in this field, an attribution factor of 40% was applied to this estimate.
- £54m per annum to safeguard the UK angling and tourism industry, by looking after fresh water fish stocks. The total value of recreational fishing is estimated at £2.7 billion per annum in the UK. In addition, the market value of fishing rights is estimated at over £3 billion. This illustrates the scale of industry at risk via stock depletion, due to diminished impacts amongst clubs and wider tourism effects – thus the maximum potential impact relating to positive intervention to sustain stocks. While the exact rate of population level effects is unknown, based on an annual 5% reduction (and a 40% contribution to this figure by Exeter University) Exeter's potential attributable impact is estimated at up to £54m per annum of safeguarded activity.
This research also strengthens the link between water pollution and rising male fertility problems. Collaborative research by the University of Exeter, Brunel University, the University of Reading and the Centre for Ecology & Hydrology, showed for the first time how a group of testosterone-blocking chemicals is finding its way into UK rivers, affecting wildlife and perhaps even humans. The research was supported by the Natural Environment Research Council and was published in the journal Environmental Health Perspectives.
The study identified a new group of chemicals that act as 'anti-androgens'. This means that they inhibit the function of the male hormone, testosterone, reducing male fertility. Some of these are contained in medicines, including cancer treatments, pharmaceutical treatments, and pesticides used in agriculture. The research suggests that when they get into the water system, these chemicals may play a pivotal role in causing feminising effects in male fish. Found in some industrial chemicals and the contraceptive pill, they enter rivers via sewage treatment works. This causes reproductive problems by reducing fish breeding capability and in some cases can lead to male fish changing sex.
Senior author Professor Charles Tyler of the University of Exeter's department of Biosciences said: "Our research shows that a much wider range of chemicals than we previously thought is leading to hormone disruption in fish. This means that the pollutants causing these problems are likely to be coming from a wide variety of sources. Our findings also strengthen the argument for the cocktail of chemicals in our water, leading to hormone disruption in fish, and contributing to the rise in male reproductive problems. There are likely to be many reasons behind the rise in male fertility problems in humans, but these findings could reveal one, previously unknown, factor."
The research team is now focusing on identifying the source of anti-androgenic chemicals, as well as continuing to study their impact on reproductive health in wildlife and humans.