This paper was the first to show that environmentally relevant concentrations of chemical pollutants present in the aquatic environment can mimic the effects of the hormone estrogen and cause biological effects in fish that are exposed to these chemicals via the water. One of these chemicals, nonylphenol, was first shown to be estrogenic in vitro in 1991 by Professor Ana Soto. In this paper, we show that not only nonylphenol, but a whole range of other chemicals present in rivers (all of which are biodegradation products of certain types of industrial detergents) are estrogenic, and, therefore, have feminizing effects on male fish. These effects can be detected by measuring the concentration of a female-specific egg yolk blood protein (vitellogenin) in male fish. This paper is important because it was also the first paper to correlate a biomarker of estrogen exposure (plasma vitellogenin in male fish) with reproductive health effects (decreased sperm production) in fish.

In the last few years, research has been published showing that estrogenic chemicals can cause increased egg production in some aquatic snails at concentrations below that which appear to affect fish. In some cases, these effects have been reported to result in blocked and ruptured oviducts and hence death. Some scientists believe that these results are incorrect. To me it’s another mystery worth investigating and my immediate research goal is to try to understand why estrogenic chemicals cause these effects in aquatic snails. In fish and other vertebrates, estrogens act through intracellular estrogen receptors. My research group is now researching whether or not such receptors exist in mollusks and if so, how do they function?

In the long term, I would like to try to understand whether or not there is any link between the widely reported reproductive health problems observed in humans with those observed in various wildlife populations around the world, including fish. I would like to develop an invertebrate test for hormonally active chemicals that will be relevant to vertebrates and hence ultimately reduce vertebrate animal testing for the effects of these chemicals. Lots of my research at the moment is concerned with investigating comparative effects of a range of hormonally active chemicals on different organisms. I would like to continue to conduct research that makes some contribution towards protecting the aquatic environment from the effects of environmental stressors.

  What are the social implications of your work, if any?

The most obvious thing to me is that the research I do (hopefully) makes some contribution towards raising the quality of the environment and therefore the quality of life.

  What tools or technological advances have been important in your research, if any?

I have certainly used a variety of tools in my research. The most useful have been the vitellogenin immunoassays developed by Charles Tyler and John Sumpter.

  What were the greatest challenges in performing and presenting your work?

Communicating with the public in a way which ensures that they understand the significance of the work.

  What lessons would you draw from your work to pass on to the next generation of researchers?

I think it would be to always keep an open mind. The more research one does, the more one learns, the more one tends to think one knows what to expect as far as research results are concerned. If the results one gets are unexpected or even unbelievable, then one should research them further and not dismiss them as artefactual or incorrect.