Deleterious effects of estrogenic endocrine disruptors on marine organisms: Histological Observed Effects and Some Novel Useful Monitoring Bioassays

Aquatic environments receive significant levels of chemical contaminants generated by human activities. Among these pollutants, we noticed the xenobiotics known as reproductive toxicants and endocrine disruptors. The endocrine disruption in wildlife has been the subject of many reviews and workshops in recent years. Field observations of reproductively abnormal organisms and population declines in polluted sites stimulated major research efforts to understand links between environmental pollution and health problems. Laboratory studies evidenced that many compounds can interfere with the synthesis, secretion, transport, metabolism, mechanism of action or clearance of natural hormones responsible for the maintenance of homeostasis and the regulation of developmental processes. These chemicals are thus defined as Endocrine Disrupting Compounds (EDC), and a list of more than 500 known or suspected EDC has been established by the European Community, such as numerous pesticides, industrial chemicals, and commercial products that have been released into the environment. Of particular importance are those that mimic estrogens and androgens (and their antagonists), because of their central role in reproductive function. Estrogens are substances both natural and synthetic that mimic the effect of the female estrogenic hormone in the body and impart estrogenic activity. Because of this effect, they potentially can disrupt the endocrine system in the exposed aquatic species. Human wastes are a major source of estrogens in the environment, too. These wastes are treated in wastewater treatment plants where some of the estrogens are removed, and the rest is discharged in the effluent. Other sources of estrogenic compounds include birth control pills and chemicals like detergents. It is important to be able to reduce their concentrations and it would be ideal if this can be achieved using available existing treatment processes. Both natural and synthetic estrogens released in the marine environment by the wastewater treatment plants are suspected to interfere with the exposed endocrine systems of aquatic species. In fact, they mimic the effect of the endogenous hormone and therefore, can disrupt the endocrine systems of exposed species and the reproductive systems of aquatic fauna. To understand their environmental fate, the estrogenic activity was studied by using the Yeast Estrogenic Screening (YES) bioassay. This bioassay has been validated in the detection of a wide range of estrogenic receptor agonists. The present work is based on in situ studies. Different compartments were used: the effluents of a wastewater treatment plant, the sea water, the sediment and the clam Ruditapes decussatus. A reverse phase HPLC method was used to identify the nature of estrogenic components. Some observed histological results showing hermaphroditic cases and parasites are also discussed in this paper.