Vitellogenin induction as a biomarker of exposure to estrogenic compounds in aquatic environments

The findings of both laboratory and field studies show that Vg induction may be considered a useful tool in evaluating endocrine disruption in aquatic animals, and thus the potential risk associated with exposure to xenoestrogens. Although further laboratory investigations will lead to improved knowledge on the mechanisms of action of estrogenic compounds and will allow us to evaluate the responsiveness of other species as bioindicators, more effort should be addressed to validate Vg induction as a biomarker in the aquatic environment. In this regard, future development of monitoring programmes should be based on the following considerations: • Vg levels may increase when animals are exposed to a wide group of contaminants having similar feminising effects; • the application of only one (or a few) biomarkers can reduce expensive chemical analyses of individual contaminants and mostly allow detection of their interactions in the environment; • the choice of the best method to measure Vg levels needs to take into account feasibility, sensitivity, reproducibility, and cost-effectiveness; • the ecological relevance of the physiological response measured is very high, considering that hormonal alterations may cause variations in the sex ratio of a wild population, its reproductive capability, and even the presence of the species in the investigated areas