I'll give my thoughts, but they are coming from a
very conservative* person.
I have an almost-19 year old daughter. When she was growing up, I faced this issue all the time. However, I was never of the opinion that she needed to be aware of all the (in my opinion) garbage going on out there all the time because I knew she would be immersed in it soon enough. To that end, I carefully screened what she read and what she watched and who she was hanging around with. In short, I made sure I knew what was going on with her at all times as much as possible. That doesn't mean that I was a shrewish, close-minded mom.
She was encouraged to talk to me about everything and anything, and she did.
I would have had a big problem with her reading anything that discussed casual sex, drugs, or the darker, seedier side of life. I don't think it's healthy for young people, and I think it can shape their minds in the wrong direction. The written word is a very powerful thing and can have a huge impact on those who are not yet old enough to reason things out properly. My .02
*this does not mean that I'm a card-carrying right-winger in the commonly understood definition of the term.