There are one or two other posts on cookware, which covers those made of titanium, but this post is in regards to its interactions with the human body. I haven't been able to find any academic/peer-reviewed articles in this subject and I don't want to go with the idea that just because its very popular means it is going to be safe.
In the article "Is that newfangled cookware safe?" no special mention is made for titanium. Titanium is not commonly found in cookware other than backpacking because it is simply terrible for any cooking tasks other than perhaps boiling water and it is expensive. Many backpackers are willing to pay the extra money for extra weight saving.
According to naturalnews titanium is the safest:
A reference article can be found here.
One pot for which I would have reservations is the grease pot. It is not made of titanium but is light, cheap and not meant for cooking. :)
I'll start by saying that it doesn't really matter how cookware material interacts with the human body, because you aren't going to eat your cookware. What is important is how it reacts with the foods that you cook, particularly acidic foods (which is why you don't want to use cast iron to make tomato sauces).
In this regard, titanium is as close to perfect as you can get, which is why it's used in laboratories and highly corrosive industrial processes. If you'd like references, I'd start with Wikipedia and go from there.