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Hormone-disrupting chemicals and climate change increase risk of extinction in wildlife

The impact of pollution on wildlife populations could be made dramatically worse by climate change according to a new study published today in the journal PNAS

University of Exeter

The impact of pollution on wildlife could be made dramatically worse by climate change according to a new study published today in the journal PNAS.

Researchers from the University of Exeter and Astra-Zeneca found that clotrimazole, a chemical that disrupts hormones and is commonly used in anti-fungal treatments, skewed sex-ratios in zebrafish in favour of males. These effects were amplified when the experiment was conducted in warmer water temperatures predicted for the year 2100 given current rates of climate change.

Inbred populations fared worse than those with higher genetic diversity highlighting the extinction risk that climate change and pollution presents to endangered species living in small, isolated populations.

Professor Charles Tyler, senior author, from the University of Exeter said: "Chemicals in the environment are usually looked at in isolation but in reality animals are exposed to multiple stressful events at the same time. They include changes in temperature, food scarcity, or harmful chemicals. It is important that we understand how these pressures interact if we are to understand the real impact of rising global temperatures and increasing levels of pollution."

Already high on the EU's agenda, restrictions over discharging hormone disrupting chemicals into the environment are likely to be tightened in the future. These restrictions are likely to affect chemical companies but also the general public who need to dispose of unused chemicals and medicines containing hormone disrupting products.

Lead author Ross Brown, formerly from AstraZeneca, now at the University of Exeter said: "Chemicals, including pharmaceuticals, bring a wide range of benefits to society. Assuring their continued safe and sustainable use requires appropriate testing and assessment, taking into account future projections for the human population and the environment. Climate change is a global phenomenon and in this study we have shown that rising temperatures could exacerbate the effects of certain chemicals in the environment, highlighting the need for appropriate assessments.".

The study was carried out with zebrafish in a controlled environment and included concentrations of clotrimazole that simulated the total loading of azole fungicides found polluting waterways.

Zebrafish are native to the Indian sub-continent but are used globally as a model in environmental research, developmental biology and medical research.

Environmental pressures on wildlife are set to increase with predicted scenarios for climate change, human population growth, and economic development. Further work to understand the interactive effects of these pressures is crucial if their damaging effects on wildlife are to be avoided.


The study was funded by the Natural Environment Research Council, the Biotechnology and Biological Sciences Research Council, the University of Exeter and AstraZeneca's Global Safety Health and Environment Research Programme.

For further information:

University of Exeter
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+44 (0)1392 722405 or 722062

About the University of Exeter

The University of Exeter is a Russell Group university and in the top one percent of institutions globally. It combines world-class research with very high levels of student satisfaction. Exeter has over 19,000 students and is ranked 7th in The Times and The Sunday Times Good University Guide league table, 10th in The Complete University Guide and 12th in the Guardian University Guide 2014. In the 2014 Research Excellence Framework (REF), the University ranked 16th nationally, with 98% of its research rated as being of international quality. Exeter was The Sunday Times University of the Year 2012-13.

The University has invested strategically to deliver more than £350 million worth of new facilities across its campuses in the last few years; including landmark new student services centres - the Forum in Exeter and The Exchange on the Penryn Campus in Cornwall, together with world-class new facilities for Biosciences, the Business School and the Environment and Sustainability Institute. There are plans for another £330 million of investment between now and 2016.

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