There are quite a variety of different types of compounds, raising concerns in different ways. One of the popular items for study is synthetic estrogens (from birth control pills). They appear to be linked to the amorphous sexual identity in fish that Grant refers to (several presenters referenced a Canadian study, in which an isolated lake was dosed to, I think, about 6 or 8 ppt. of estrogen, and the minnow population crashed completely within something like 6 years; several also talked of a Colorado plant - maybe Denver - just below a dam, so there was good control, and evidence that the STP was causing similar problems in the stream). Other items showing up at levels of concern are fabric brighteners, found in detergents; antidepressants (such as Prozac); fire retardants; and pain relievers (such as Tylenol), among the hundreds of compounds they are finding. No one seems certain at this time about what is a "safe" level of these things, especially since some occur in certain forms in nature (such as the estrogen). Treatability varies with the compound, and some may break down in a biological plant, while at the same time being created as a byproduct of the breakdown of other substances. The sheer number of products, with different characteristics, makes it difficult.

Adding to the problem (at least in the U.S.), is that official policy still seems to be that disposal of unused pharmaceauticals should be by flushing down the loo. People have managed occasionally to set up community disposal days for the pharms. (for eventual incineration), and found one of the biggest stumbling blocks to be the police agencies, such as DEA, who were afraid of stuff finding its way back onto the street. One person, who spoke of arranging one of these events, talked of finding (since all the bottles had to be sorted and cataloged), an unopened / unused bottle of a cancer treatment medicine that cost $10,000, and was sent off for destruction. The original patient had died before it could be used. An incredible waste, and one that could have ended up at the STP. 

This issue is gaining some momentum, and I'm guessing that it will replace conventional stormwater as the next "hot" topic. Have no idea what sort of rules would come about, but it seems to be attracting public attention, and  am pretty sure it won't be real long before there is a demand to " Do Something ! !".