It depends on the type of adhesive you use and which parts of the body you decide to join. For example most parts of the body can be joined with wallpaper paste, pritt stick or blu tack.
Cyanoacrylates (superglues) are a different matter and can cause blindness if attempting to join eyes together. I would also suggest keeping this sort of adhesive away from the reproductive organs.
Any solvent based glue can also be harmful (if mildly stimulating) if gluing near to the mouth or nose.