A Global Inventory of Natural and Synthetic Estrogens in Aquatic Systems

Estrogens are a group of endocrine disruptors that are recognized as a threat to the world's ecosystems and are easily transported through aquatic systems from mainly anthropogenic sources. To illustrate this growing problem, we have compiled a global overview of measured concentrations of natural and synthetic estrogens restricted to freshwater systems (lakes, rivers, and lagoons) and marine coastal and open ocean environments, focusing on estrone (E1), 17$\upbeta$-estradiol (E2), estriol (E3), and 17$\upalpha$-ethinylestradiol (EE2). We found that the cumulative risk quotient is high at 65% of 400 sampled sites, highlighting that estrogen pollution is a major environmental concern. Our investigation revealed that almost no information is available on the concentration levels of E1, E2, E3, and EE2 for the open ocean areas. However, their occurrence in all systems, including open seas, suggests that estrogens are not completely degraded during transport to and within the environment and may be more persistent than previously thought.