Xenoendorine disrupters--environmental impacts.

There is now unequivocal evidence that a wide variety of chemicals capable of disrupting the endocrine system are present in the aquatic environment. These range from natural (e.g. 17beta-oestradiol) and synthetic (e.g. ethinyl oestradiol) oestrogens through to industrial chemicals that can mimic endogenous hormones (e.g. nonylphenol, some pesticides). Relatively little is known about the fate and behaviour of these chemicals in the aquatic environment, and hence it is unclear which organisms are exposed to the chemicals, and to what degree. This makes predicting possible effects difficult. Nevertheless, enough examples, such as the masculinisation of female molluscs exposed to the anti-fouling agent TBT (tributyltin), and the feminisation of male fish exposed to oestrogenic chemicals in effluent from sewage-treatment works, are documented to demonstrate that adverse affects are occurring. The challenge now is to assess how wide-ranging these adverse effects are, to determine their severity at the population level, and to gauge how serious an issue endocrine disruption is compared to other factors (such as habitat loss) which are also adversely impacting aquatic organisms.