What are hormone mimics? In general a number of compounds including some naturally-occurring chemicals have the ability to mimic natural hormones in animals & humans. Most of the research has been on estrogen mimics causing males to become hermaphrodites. Early indicator species include small mouth bass - but early research also found a huge impact in alligators in Florida in the 1990s.
What is important is the concentration of hormone mimics in waters causing disruption in indicator species. We do not know the long run impact on higher trophic level organisms including humans. So, the next generation of wastewater permits will start to also include reduction of hormone mimics and pharmaceuticals that are currently passing through conventional wastewater treatment systems. The issue is how to remove these compounds without excessive costs or other environmental impacts.
I am including a link the National Geographic story. A online search will also give further references on hormone mimics and regulators efforts to remove problematic chemicals from waters.