Endocrine disruptor risk characterization: an EPA perspective.

The characterization of risk to endocrine-disruptive agents may prove to be one of the greatest challenges that the risk assessment/regulatory community has ever faced. Why is this so? The endocrine system is actually many systems, having complex interactions and interdependencies. Normal endocrine function is often dependent on cyclical events, rather than steady-state. Timing is everything, as evidenced by significant differences in adverse outcome as a function of age and stage of development. Further, the consequences of concomitant exposures to endocrine-active substances in the diet or as therapeutic agents are poorly understood. So, how should risk characterization to these agents be approached? This presentation will include the description of current practices for addressing hormonally mediated cancer and noncancer effects and offer speculation on modifications to these approaches that might be necessary as our knowledge of this area increases.