I have heard conflicting viewpoints- many people say that Feline Pine is the safest, healthiest, most natural litter available, but other sources say that their process may not remove all of the pine oils which are harmful to cats. They do smell an awful lot like pine, which makes me think that they may still contain some aromatic oils.
If you want an alternative that is more natural and safer, I recommend Yesterday's News or a similar product. It's basically pelleted paper, and the pellets are a little smaller than the Feline Pine pellets and have no real odor. We use Yesterday's News in the cat kennels at my school, and it's very absorbent and doesn't produce dust like Feline Pine does.
"I remember the days when we talked for hours/And we were young, we thought we had superpowers/We weren't our problems, our age or our paychecks/And we weren't taking anybody's $h*t."