Endocrine disruptor screening: regulatory perspectives and needs

Since the middle of the 1990 s, there has been increasing awareness and concern regarding the exposure to chemicals that have the potential to interfere with the endocrine system, and thus, may cause health effects in people and wildlife. In fact, a great number of chemicals have been identified that were found to interact with the endocrine system of different animals in laboratory studies, and there are increasing reports of endocrine disruption in wild animals [1,2]. The potential role of endocrine disrupting chemicals in the environment has been discussed extensively for several years in both science and the broader public. On the one hand, there is evidence from various laboratory experiments that estrogenic or estrogen-like compounds have the potential of affecting development of the reproductive and nervous systems, as well as behavior and immune response in higher organisms [3,4]. On the other hand, it is still unclear if environmentally relevant concentrations of xenoestrogens can result in deleterious effects in wildlife populations, and to date - with few exceptions - there has been no direct evidence of such population relevant impacts in the wild [5,6]. In fact, few studies have attempted to explore the ecological relevance of the exposure to endocrine active chemicals under field conditions. One example is a recent whole-lake study that was conducted over 10 years at the Experimental Lakes Area in Canada that revealed clear evidence that the potent synthetic estrogen 17β-ethynylestradiol (EE2) affects fish populations and their supporting food web [7]. The population of the shortest-lived fish species, the fathead minnow, collapsed after two summers of EE2 additions. There is consequently an urgent need in understanding the relevance of lab-based experiments with endocrine disruptive chemicals (EDCs) in context with ecological scenarios.These reports and associated concerns regarding the ubiquitous presences of EDCs in the environment have sparked both