Some of the effects of this problem have been known for a while, such as the effects on fish of the hormones in effluent. It is easy to suppose that this is just another in the long list of environmental polluters that we have to put up with - in the past we suffered with lead in the paint and the air, and there are plenty of more recent pollutants.
On of the frustrations with drugs being added to the list of environmental hazards is that they are not being disposed of / collected properly. HCWH state the low percentage of drugs being collected back when not used and it is reasonable to speculate that much of the rest is flushed down toilets.
The other key issue is the over reliance of drugs. I have blogged before on the problems of polypharmacy - which are many. Interactions are clearly the main issue but aside from increasing the profits of BigPharma we ought to add the pollution to water supplies to the list of problems.