It's not unused meds being flushed, it's all meds that all of us are taking daily, and OTC stuff, etc. going through our bodies (when we pee, etc. :-) The medical news guy said it's equivalent at the moment to a sugar cube being dissolved in an olympic swimming pool of water, not a problem yet but "new" because there has been a huge increase in the amount of meds everyone is being prescribed/taking the last 10-20 years.

They don't know "what" so they don't know how to fix it because it can't be imagined properly yet, nobody knows if it is doing us harm, etc. They're studying fish, who have been living in this stuff for that long, monitoring changes in them, etc. but who knows what it might or might not be doing to humans? If you can't know what to test for in any given area, how do you build a filter for it?