Disruptive potential of environmental estrogens on fish reproduction.

F. J. MEIJIDE

Porto Alegre

Congreso; 1st Latin American Congress of Clinical and Laboratorial Toxicology. Toxi-Latin 2014.; 2014

Universidade Federal do Rio Grande do Sul

Among endocrine disrupting chemicals of human origin, estrogen-mimetic compounds or xenoestrogens are of primary importance regarding their presence in the environment. Since their discovery, the concern about the potential ecological and human health impact of these substances has been growing. The aquatic environment, in particular, is the depository of large amounts of xenoestrogens. Alkylphenol ethoxylates and their degradation products, which are used in various industrial activities, as well as the natural and synthetic estrogens used to elaborate drugs by the pharmaceutical industry, stand out among the numerous compounds exhibiting estrogenic activity. While some of these chemicals have been prohibited in some countries, they are still produced and/or used in many others. Environmental levels of these compounds usually exceed the thresholds for which endocrine disruption has been demonstrated both in laboratory essays and in the natural environment. Taking into account the results of acute and chronic laboratory essays, a general consensus is achieved in order to establish the maximum levels allowed for the different types of pollutants present in aquatic systems. Usually, the analysis of biomarkers in concentration -response experiments provides the information used to set up the limits for wildlife protection. However, it is difficult to estimate the consequences of long term exposure to low levels of contamination, as well as of the effect of bioaccumulation. In certain cases, it might be argued whether an endocrine alteration at the individual level represents a real adverse effect at the population level which might endanger a given species. Few studies have addressed this issue and the results are not conclusive. In addition, most effects, both at the individual and population levels, show to be reversible upon cessation of contaminant exposure. Nonetheless, when evidences about the ultimate effects of a contaminant are not clear, it is prudent to apply the precautionary principle. Among aquatic organisms, fishes are commonly used as models in ecotoxicology essays. However, although fishes represent more than 50% of the living vertebrate species, only a few are employed in scientific research. In this presentation, results about the effects of exposure to xenoestrogens on reproduction of the cichlid fish Cichlasoma dimerus, a native species used in our laboratory as a model in ecotoxicology research, will be presented. These results provide new evidence to that derived from studies performed in other species. The significance of these findings will be evaluated in terms of the real hazard for fish populations in the natural environment. In addition, the most suitable methods to assess the environmental effects of these pollutants and the mitigating measures that should be taken will be discussed.